class notes for pyp 001 semester 132 (3)

By Jawad Ahmad

King Fahd University of Petroleum & Minerals – Prep Year Preparatory Physical Science & Engineering Program - (132) Semester

Course Name & Code: Preparatory Physical Science - PYP001

Textbook: “Physical Science, Exploring Matter & Energy” by G. de Mola. Course Coordinator:

Dr. Tayseer Abu Alrub Office: Building 58 Ground Floor Room 0019

Telephone: 7083 (office) E-mail: [email protected] Instructor Name: Jawad M Ahmad Office: Building 58 Ground Floor Room 0011

Telephone: 7623 (Office) E-mail: [email protected] Course Website: http://www.kfupm.edu.sa/sites/phypyp/default.aspx Course Description Introduction to basic concepts of Physics (Newton’s laws of motion;

momentum & energy; work & power; waves; electricity& magnetism) and Chemistry (states of matter; properties of matter & atomic structure; radioactivity & nuclear reactions and their applications); water resources as a selected topic from Earth Science.

Course Objectives: Review basic concepts in Physical Sciences through which students would be equipped with

general English scientific terminology. Develop and stimulate students’ interest in Physical Sciences. Engage students in reading scientific text.

Attendance is compulsory. It will be enforced and evaluated according to current university regulations. DN grade shall be given to students who accumulate 5 or more unexcused absences or a total (excused and unexcused) of 8 or more absences. A student, who has a valid excuse for an absence, must present an officially authorized document to his instructor no later than one week following his resumption of classes. No excuses will be accepted after posting the final grades.

Grading Policy: Class Work 20% (Attendance 2%, Class Quizzes 8%, Online Quizzes 5% & Online Home Works 5%) Major Exam I 20% [Week 06] Major Exam II 20% [Week 11] Final Exam 40% [Saturday, May 24, 2014 at 12:30 PM] __________________________ Total 100% Teaching Method: Lectures-Blackboard, Multimedia (Power Point Presentations), WebCT-

eLearning, Interactive and/or Group Work, Practical Demonstrations. Make-up Exam Policy: A student, who misses an exam, must present an official and valid

document (excuse) to the instructor within 7 days after the exam so as to be eligible for a make-up. If not, the score for that exam will be zero. Personal excuses will not be accepted.

Cheating is unethical. Proved cases of cheating would entitle concerned students to zero marks (in exams or other assessments) and the possibility of dismissal from the University.

By Jawad Ahmad

PYP001 Syllabus and Lecture Schedule [UW] - (Term 132) Course Name & Code: Preparatory Physical Science- PYP001

Textbook: “Physical Science, Exploring Matter and Energy” by G. L. de Mola

Week DATE TOPIC SECTION * HW

1 26-01-14 29-01-14

Introduction Classifying Matter, Elements

--- 2.1, 2.2

HW-1

2 02-02-14 05-02-14

Physical Properties, Physical Changes Chemical Properties, Chemical Changes

3.1, 3.2 3.3, 3.4

HW-2

3 09-02-14 12-02-14

Solids, Liquids Gases, Changes of State

4.1, 4.2 4.3, 4.4

HW-3

4 16-02-14 19-02-14

Improvements to the Atomic Model, Properties of Subatomic Particles Radioactivity, Nuclear Decay and Radiation

5.2, 5.3 11.1, 11.2 HW-4

5 23-02-14 26-02-14

Nuclear Reactions and Their Uses Measuring Motion, Velocity and Acceleration

11.3 12.1, 12.2

HW-5

6 02-03-14 05-03-14

Velocity and Acceleration, Momentum What is Force? Friction

12.2, 12.3 13.1, 13.2

HW-6

7

09-03-14 12-03-14

Gravity Gravity, Newton’s Laws of Motion

13.3 13.3, 13.4 HW-7

8 16-03-14 19-03-14

Newton’s Laws of Motion Work and Power

13.4 15.1

HW-8

Midterm Vacation 23-27, March, 2014

9 30-03-14 02-04-14

What is Energy?, Energy Conversions Energy Conversions, Energy Resources

16.1, 16.2 16.2, 16.3

HW-9

10 06-04-14 09-04-14

The Nature of Waves, Types of Waves Types of Waves, Properties of Waves

19.1, 19.2 19.2, 19.3

HW-10

11 13-04-14 16-04-14

The Nature of Sound, Properties of Sound What is an Electromagnetic Wave?, The Electromagnetic Spectrum

20.1, 20.2 21.1, 21.2 HW-11

12 20-04-14 23-04-14

The Electromagnetic Spectrum, Producing light What is Electric Charge?, Static Electricity

21.2, 21.3 23.1, 23.2

HW-12

13 27-04-14 30-04-14

Making Electrons Flow, Electric Power The Nature of Magnets, Making Magnets

23.3, 23.5 24.1, 24.2

HW-13

14 04-05-14 07-05-14

Earth as a Magnet Magnetism from Electricity, Electricity from Magnetism

24.3 25.1, 25.2

HW-14

15 11-05-14 14-05-14

Water Resources Water Resources

Chapter 26 (#) HW-15

Final Exam: Saturday, 24/05/2014, at 12:30 PM.

* Section 2.1 = Chapter two, section one

# Chapters 26 is not from the textbook, it will be provided by the department.

By Jawad Ahmad

PYP001 Syllabus and Lecture Schedule [MR] - (Term 132) Course Name & Code: Preparatory Physical Science- PYP001

Textbook: “Physical Science, Exploring Matter and Energy”by G. L. de Mola

Week DATE TOPIC SECTION * HW

1 27-01-14 30-01-14

Introduction Classifying Matter, Elements

--- 2.1, 2.2

HW-1

2 03-02-14 06-02-14

Physical Properties, Physical Changes Chemical Properties, Chemical Changes

3.1, 3.2 3.3, 3.4

HW-2

3 10-02-14 13-02-14

Solids, Liquids Gases, Changes of State

4.1, 4.2 4.3, 4.4

HW-3

4 17-02-14 20-02-14

Improvements to the Atomic Model, Properties of Subatomic Particles Radioactivity, Nuclear Decay and Radiation

5.2, 5.3 11.1, 11.2 HW-4

5 24-02-14 27-02-14

Nuclear Reactions and Their Uses Measuring Motion, Velocity and Acceleration

11.3 12.1, 12.2

HW-5

6 03-03-14 06-03-14

Velocity and Acceleration, Momentum What is Force? Friction

12.2, 12.3 13.1, 13.2

HW-6

7

10-03-14 13-03-14

Gravity Gravity, Newton’s Laws of Motion

13.3 13.3, 13.4 HW-7

8 17-03-14 20-03-14

Newton’s Laws of Motion Work and Power

13.4 15.1

HW-8

Midterm Vacation, 23-27, March 2014

9 31-03-14 03-04-14

What is Energy?, Energy Conversions Energy Conversions, Energy Resources

16.1, 16.2 16.2, 16.3

HW-9

10 07-04-14 10-04-14

The Nature of Waves, Types of Waves Types of Waves, Properties of Waves

19.1, 19.2 19.2, 19.3

HW-10

11 14-04-14 17-04-14

The Nature of Sound, Properties of Sound What is an Electromagnetic Wave?, The Electromagnetic Spectrum

20.1, 20.2 21.1, 21.2 HW-11

12 21-04-14 24-04-14

The Electromagnetic Spectrum, Producing light What is Electric Charge?, Static Electricity

21.2, 21.3 23.1, 23.2

HW-12

13 28-04-14 01-05-14

Making Electrons Flow, Electric Power The Nature of Magnets, Making Magnets

23.3, 23.5 24.1, 24.2

HW-13

14 05-05-14 08-05-14

Earth as a Magnet Magnetism from Electricity, Electricity from Magnetism

24.3 25.1, 25.2

HW-14

15 12-05-14 15-05-14

Water Resources Water Resources

Chapter 26 (#) HW-15

Final Exam: Saturday, 24/05/2014, at 12:30 PM.

* Section 2.1 = Chapter two, section one

# Chapters 26 is not from the textbook, it will be provided by the department.

By Jawad Ahmad

Semester 132 Schedule

PYP 001

Building 61

Sunday & Wednesday Monday & Thursday

Time Room 107 Room 108 Room 107 Room 108

8:00 am Musazay Section 1

Tayseer Section 2

Musazay Section 3

Tayseer Section 4

9:00 am Jawad Section 5

Tayseer Section 6

Musazay Section 7

Tayseer Section 8

10:00 am Ashraf Section 9

Saleem Section 10

Jawad Section 11

Saleem Section 12

11:00 am Ashraf Section 13

Saleem Section 14

Jawad Section 15

Saleem Section 16

Lunch

12:50 pm Ashraf Section 17

Jawad Section 18

Jawad Section 19

Ashraf Section 20

1:50 pm Ashraf Section 21

Jawad Section 22

Jawad Section 23

Ashraf Section 24

3:00 pm Musazay Section 25

Saleem Section 26

Musazay Section 27

Saleem Section 28

4:00 pm Musazay Section 29

Saleem Section 30

Musazay Section 31

Ashraf Section 32

By Jawad Ahmad

Class Notes 132 Semester

Write your name and student ID on the front page and back page of your textbook. Go on Blackboard every week to do your online homework and online quiz. The course website is http://www.kfupm.edu.sa/sites/phypyp/default.aspx These notes are not a substitute for reading the book. Read the book. Chapter 2 Types of Matter 2.1 Classifying Matter

Matter: Anything that has mass and volume. Mass is the amount of stuff in an object and has units of kilograms. Mass and w⃑⃑⃑ eight are not the same thing. The volume of an object is the number of cubes in a 3D object and has units of meters cubed m3.

What is not matter? Some examples of things that are not matter are light, heat, electromagnetic waves (see page 357), and sound.

Pure Substances

Molecule: A particle created/formed when two or more atoms combine. A molecule is not a single atom. A molecule is created when two or more atoms combine like N2, H2, CO2, H2O, etc. The atoms combining can be the same (N2 or H2) or different (CO2 or H2O).

Compound: A pure substance in which two or more different elements combine. Examples of a compound are carbon dioxide CO2, ammonia NH3, table salt NaCl, and water H2O. The atoms have to be different. The ratio of elements in a compound is always the same.

All compounds are molecules but not all molecules are compounds. A molecule is formed when two or more atoms join together chemically. A compound is a molecule that contains at least two different elements. (From http://education.jlab.org/qa/compound.html)

Ratio: Examples: Water (H2O) has two H atoms for each one O atom. For every five games a football team plays, they lose two games. This is a ratio of 5:2. For every 16 hours I am awake, I sleep 8 hours. This is a ratio of 16:8.

Element: An object/substance in which all of the atoms are the same. See pages 94-95.

Pure Substance: Object made of only one type of particle. Examples of a pure substance are a gold bar, silver coin, pure water, pure carbon dioxide, etc. A pure substance can be an element or a compound.

All elements are pure substances but not all pure substances are elements. Mixtures

Mixture: An object that is made of several substances that can be separated physically. Example: A fruit salad. You can mix different fruits together but they don’t physically combine. You can separate the fruits with your hand.

Mixtures do not always have the same ratio of the substances that make them up. For example, if you buy a fruit salad and give some of the fruit salad to your friends, some friends may have more of one type of fruit than other friends.

Heterogeneous Mixture: Different materials/objects in a mixture that can be seen easily. Examples of a heterogeneous mixture are sand and soil, water and oil, and a fruit salad.

Homogeneous Mixture/Solution: Different materials/objects in a mixture that cannot be seen easily. Examples of homogeneous mixtures are air, ocean water, antifreeze, Pepsi and tea.

See Figure 2.4 on page 23 and memorize it.

By Jawad Ahmad

2.2 Elements

An element is a pure substance made up of only one type of atom. An element is the simplest type of pure substance. Example: A gold bar.

Discovery of Elements

There are 117 known elements. 92 are found in nature. The rest are made artificially in a laboratory which are unstable and exist for only a short time.

Describing Elements

The name of an element is abbreviated by a chemical symbol. The chemical symbol for iron is Fe, gold is Au, silver is Ag, etc. See Figure 6.4 on pages 94-95.

In a chemical symbol the first letter is always capitalized. The second letter is always lowercase.

The Makeup of Elements

See the periodic table of elements (Figure 6-4 on pages 94-95.).

An element is made up of atoms.

We need electrons e-, protons p+, and neutrons to make an atom. The basic model of an atom is a spherical (A sphere is a three dimensional 3D circle.) object with neutrons n and protons p+ in the center of the sphere (nucleus) and a cloud of electrons e- outside the center. See Figure 2.7 on page 26.

An element is defined by the number of protons p+ in its nucleus. Hydrogen H will always have one proton p+. Hydrogen H may have 100 neutrons n or 1000 electrons e- but it will always have one proton p+.

What if a hydrogen H atom has two protons p+? Then we have a helium He atom, not a hydrogen H atom.

What’s the definition of gold Au? Gold Au will always have 79 protons p+. That’s the definition of gold. Silver Ag will always have 47 p+. Elements are defined by the number # of protons p+ in its nucleus.

We can only see objects that are longer than the wavelength of visible light. Since the length of an atom is shorter than the wavelength of visible light we cannot see atoms with our eyes or with a microscope. We cannot see atoms directly. The diameter (diameter =2 × radius) of an atom is about 2 × 10−10 m = 0.2 nm.

By Jawad Ahmad

Chapter 3 Properties of Matter 3.1 Physical Properties

A physical property of an object is a characteristic/description that can be observed/seen without changing the compounds or molecules of an object into different compounds or molecules.

A property of an object is a characteristic/trait/feature that can be used to describe the object. Some examples of a property of an object is if it is large or small, the color, whether it is flammable or not, etc.

Observable Properties

An observable property of an object is a characteristic of an object that you can determine by using your senses: sight, touch, sound, smell, or taste. Some examples of an observable property are the color of an object, whether it is rough or smooth, hard or soft, and its state of matter (Is the object a solid, liquid, gas, or plasma?).

Measurable Properties

You cannot determine the length, mass, volume, boiling point, melting point, density, or specific gravity of an object by using your five senses. You have to use an instrument/tool to find this out. A measurable property is when you need an instrument/tool/object to determine a characteristic of an object.

The density of an object is the mass of an object divided by its volume. ρ =mass

volume= [

kg

m3].

See Figure 3.4 on page 42.

The specific gravity of an object is a ratio of the density of an object to the density of

another object. specific gravity =ρobject 1

ρobject 2⁄ . Question: What are the units of

specific gravity? Kinds of Properties

An intensive property is a property that does not depend on the amount of matter present. The boiling point, melting point, temperature, and color of an object are examples of intensive properties.

An extensive property is a property that depends on the amount of matter present. The mass and volume of an object are two examples of extensive properties.

The book gives a good example of taking a small amount of water from a swimming pool (Figure 3.5 on page 43.) to compare the two properties.

3.2 Physical Changes

A physical change is when an object changes how it looks without changing its composition (The molecules and compounds in an object don’t change). Some examples are cutting wood, bending a wire, blowing up a balloon, stretching a rubber band, breaking glass, etc. See Figure 3.8 on page 45.

Changes of State

H2O being converted from solid ice to liquid water is another example of a physical change. The object/compound is still H2O.

A change of state is a physical change since the molecules or the compounds of an object do not change.

By Jawad Ahmad

3.3 Chemical Properties

A chemical property describes how the molecules or compounds of an object changes (or doesn’t change) when it interacts with other objects or energy.

An example of a chemical property is silver tarnishing (See Figure 3.10 on page 47.) or iron rusting (See Figure 3.11 on page 48.).

Another example of a chemical property is when iron is combined with nitrogen gas at room temperature and nothing happens.

You cannot determine a chemical property just by looking at an object. A chemical property is determined/observed only when the molecules or compounds of an object changes.

Flammability is another chemical property. This is when an object will burn, or catch on fire, easily. Objects that catch on fire easily are flammable. Pure oxygen, gasoline/petrol, and paper are flammable.

By Jawad Ahmad

3.4 Chemical Changes

A chemical change occurs/happens when one type of matter changes into another type of matter.

In a physical change the properties of the original object are the same as the properties of the new object.

In a chemical change the properties of the original object are different from the properties of the new object. Example: Hydrogen and oxygen are both flammable but H2O is not flammable.

The new substance/object cannot be changed/converted to the old substance/object easily in a chemical change.

An example of a chemical change is when hydrogen burns in oxygen. H2O is formed. The H2O cannot easily be changed to hydrogen and oxygen easily. It will take a lot of energy and time to do this.

Chemical Properties vs. Chemical Changes

A chemical property is when an object has the ability to change the molecules or compounds in it. A chemical change is when the molecules or compounds in an object are altered/changed.

An example of this is petrol/gasoline. Petrol is flammable. That is a chemical property. A chemical change is when the petrol burns.

Another example is iron. Iron rusts. That is a chemical property. A chemical change is when the iron rusts.

Chemical Changes All Around

Some examples of chemical changes are the burning of a candle, food cooking, fruit ripening, silver tarnishing, iron rusting, copper forming patina, etc.

In caves H2O and CO2 combine to form carbonic acid which can break rocks. See the figure on page 40.

In photosynthesis, which is a chemical change, plants convert CO2 and H2O to sugar and O2. The energy that makes this happen comes from the sun.

In cellular respiration animals and humans use O2 to break down sugars into energy.

Energy is what we need to do work. Work is when we move an object. See chapters 15 and 16.

Signs of Chemical Change

There are some signs that tell us that a chemical change may have occurred/happened.

If the total amount of energy in an object decreased, or if energy is released, then a chemical change may have occurred/happened. Example: Light is released from an object.

If a gas is formed then a chemical change is likely to have happened. Example: An antacid or vitamin c tablet is dropped in water.

Sometimes a solid is formed/created when two liquids are mixed together. This is called precipitate. This is a chemical change.

A chemical change may occur when the color of an object is changed. Example: A half eaten apple changes color.

The change in smell, or odor, of an object is another sign that a chemical change may have taken place. Example: Rotten eggs.

Conservation of Mass

The law of conservation of mass states that the total amount of mass in the whole universe is constant. Mass can be converted to energy.

Read the Chapter 3 Summary on Page 52.

By Jawad Ahmad

Chapter 4 States of Matter

Matter exists in different states (solid, liquid, gas, plasma) and can change from one state to another when it gains or releases energy. Example: Water.

Question: Which particle has the most energy? A solid, liquid, or gas?

All atoms are in constant motion. Some atoms move more than other atoms, meaning some atoms have a larger speed than other atoms.

Solids, liquids, and gases (states of matter) are determined by how fast particles move and how strongly they are attached to each other.

More than 99% of matter in the universe is plasma. Plasma is found in stars because it exists at high temperatures. Plasma is created artificially in fluorescent bulbs, neon lights, and in plasma screen televisions. It is seen naturally in lightning.

4.1 Solids

The three states of matter on Earth are solids, liquids, and gases. Characteristics of a Solid

Solids have a definite shape and a definite volume. If you move a solid, the shape and size will not change. The particles in a solid are packed tightly in fixed positions. The particles move but they only vibrate about a fixed position.

Types of Solids 1. Crystalline solid: Particles are in an organized/repeating 3D order/pattern. See Figure 4.3 on

page 57. Examples: Salt, sugar, sand, and ice. 2. Amorphous Solid: Particles are not arranged (not organized) in any order/pattern.

Examples: Rubber, glass, and wax. 4.2 Liquids

Lava is rock in a liquid state. Lava comes from volcanoes. When lava cools it becomes rock. Characteristics of a Liquid

Liquids have a definite volume but no definite shape. Liquids take the shape of the container. Liquid particles have enough energy to move past one another.

Particles in a liquid move more quickly/rapidly than particles in a solid. Surface Tension

Sometimes a small animal can walk/float on water. How is this possible? The surface

tension is created when uneven f orces (a push or a pull) act on the particles at the surface of a liquid. See Figure 4.6 on page 59.

Water particles pull other water particles toward each other. The water particles on the top have no other particles to pull toward it from above. Because of this a thin film (or a thin layer) is created at the surface of the liquid.

If only a small amount of liquid is present then the surface tension pulls the liquid into a spherical shape.

The Jesus Lizard can run on water.

In order to mimic the lizard, a human would need to run at almost 30 meters per second, "a velocity beyond human ability." A man would also need "an average power output almost 15 times greater than the maximum sustained power output for humans." http://www.popularmechanics.com/technology/digital/fact-vs-fiction/water-runner-physics-debunked

Viscosity

Viscosity is the f orce of friction of a liquid, or its resistance to flow.

The viscosity of a liquid depends on the attraction between its particles. The stronger the attraction between its particles, the slower the liquid flows and the greater the viscosity of the liquid will be.

Example: The viscosity of honey is greater than the viscosity of water.

By Jawad Ahmad

4.3 Gases

A gas has no definite volume and no definite shape. A gas will move rapidly/quickly and gas particles will have a great distance from one another.

Just like a liquid, a gas will take the shape of the container that it is in.

Diffusion is a uniform/constant spreading of gas. Gas fills a room of any dimensions. Gas Pressure

A f orce is a push or a pull.

Pressure=Force/Area=[Newton/m2]=[Pascals]

Compression occurs/happens when you increase the number of particles in a constant/fixed volume or when you decrease the volume of an object with a fixed number of gas particles inside it.

The opposite of compression is decompression, or when you decrease the number of particles in a constant/fixed volume or when you increase the volume of an object with a fixed number of gas particles inside it.

Directly Proportional Relationship: As x increases, y increases. Y=KX (X and Y are variables and K is a positive constant.) Example: The more money I have, the more friends I have. The less money I have, the fewer friends I have. The more money I have, the more handsome I am. The less money I have, the less handsome I am.

Inversely Proportional Relationship: As X increases, Y decreases. Y=K/X (X and Y are variables and K is a positive constant.) Example: The less I exercise, the more mass I have. The more I exercise, the less mass I have. The more time I spend watching football, the less time I have time to study. The less time I spend watching football, the more time I have to study.

Boyle’s Law

Boyle’s Law: If the number of molecules of a gas in a container is constant and the temperature of the gas is constant, then the volume of the gas is inversely proportional to the pressure of the gas. See Figure 4.10 on page 61.

Charles’s Law

Charles’s Law: If the number of molecules of a gas in a container is constant and the pressure of the gas is constant, then the volume of the container is directly proportional to the temperature of the container. Example: If you increase the temperature of the gases in a tire, the tire will pop. See Figure 4.11 on page 62.

Charles’s Law and Boyle’s Law can be seen from the Ideal Gas Law PV=nRT, where P=Pressure, V=Volume, n=number of molecules of gas, R=Constant, and T=Temperature.

Absolute zero occurs when the temperate of an object is 0 Kelvin (or -273.15°C). At absolute zero all particles stop moving.

The current world record was set in 1999 at 100 picokelvins (pK), or 0.000 000 000 1 of a Kelvin, by cooling the nuclear spins in a piece of rhodium metal. http://en.wikipedia.org/wiki/Absolute_zero

By Jawad Ahmad

4.4 Changes of State

A change of state the conversion of a substance/object from one state to another (Example: Solid Liquid, Solid Gas, and etcetera). The molecules or compounds of the object does not change as it converts from one state to another. For example, water (liquid) that turns to ice (solid) will still have the chemical composition as H2O.

Energy

Energy is something that lets us do work. We do work when we move an object (work =

F⃑ orce × d⃑ isplacement).

A change of state requires a change in energy. If we convert an object from a solid to a liquid, the object will gain energy since a liquid moves more than a solid. If we convert an object from a liquid to a solid, the object will lose energy since a solid will move more slowly than a liquid.

Kinetic energy is the energy of a moving object. The kinetic energy of a moving object is

given by the equation KE =1

2mv⃑ 2, where m is the mass of the object and v⃑ is the velocity of

the object. If the object is at rest then the kinetic energy of the object is 0 Joules.

The thermal energy of an object is the total kinetic energy of all the particles in a sample/group. Thermal energy is absorbed (taken in) or released (lost) when an object changes from one state to another.

Heat is the thermal energy that is transferred/moved from one substance/object to another.

Matter gains thermal energy when it is heated (Example: Solid Liquid or Liquid Gas or Solid Gas). Matter loses thermal energy when it is cooled (Example: Liquid Solid or Gas Liquid or Gas Solid).

The temperature of an object is the average kinetic energy of all the particles in a sample/group.

Melting

Melting is the change of state from a solid liquid. When an object melts it gains energy.

The melting point of an object is the temperature at which a substance/object changes from a solid to a liquid.

Amorphous solids (glass, wax, rubber, and plastics) don’t have a definite/exact melting point.

Crystalline solids (salt, sugar, sand, ice, quartz) have a definite/exact melting point. Freezing

Freezing is the change of state from a liquid solid. When an object freezes it loses energy.

The freezing point of an object is the temperature at which a substance/object freezes.

Since freezing is the reverse/opposite of melting, the freezing point = melting point. Vaporization

Question: Why do people perspire/sweat? Pigs do not perspire/sweat, so how do they cool off? What about dogs?

Vaporization is the change of state from a liquid gas. When an object vaporizes it gains energy.

There are two types of vaporization: 1. Boiling is vaporization that occurs/happens throughout a liquid (Example: Boiling

water to make tea.). The boiling point of an object is directly proportional to the pressure.

2. Evaporation is vaporization that occurs/happens at the surface of a liquid and at temperatures below the boiling point of a substance (Example: Perspiring/sweating or water evaporating in a lake.).

By Jawad Ahmad

Condensation

Condensation is the change of state from a gas liquid. During condensation a gas loses energy.

Since condensation is the opposite of boiling, the condensation temperature = vaporization temperature.

Sublimation

Sublimation is the change of state from a solid gas. During sublimation an object gains energy. Example: Dry ice is carbon dioxide CO2 in a solid state. The dry ice turns from a solid to a gas when it is exposed to room temperature.

Analyzing a Heating Curve

An endothermic process is a process that requires an absorption/gain of energy (Example: Melting, vaporization, and sublimation). Eating is an example of an endothermic reaction since you’re gaining energy when you eating.

An exothermic process is a process that requires a release/loss of energy (Example: Freezing and condensation.). Exercising is an example of an exothermic reaction since you’re losing energy when you exercise.

See Figure 4.19 on page 67:

In area A of the graph the ice will absorb (take in) heat and will go from -20°C ice to 0°C ice.

In area B of the graph the ice goes from 0°C solid ice to 0°C liquid water. During the change of state the temperature of the object does not change as the solid ice melts to liquid water. It takes energy to convert the object from solid ice to liquid water. At 0°C the object can be solid ice or liquid water.

In area C of the graph heat will be absorbed (taken in) by the liquid water starting at 0°C and the heat will increase the temperature of the liquid water until its temperature is 100°C.

At 100°C the object goes from 100°C liquid water to 100°C gas vapor. The temperature of the water does not change as the liquid water vaporizes. It takes energy to convert the object from liquid water to a gas vapor. At 100°C water can be a liquid or a gas.

By Jawad Ahmad

Summary:

Energy ↓ Exothermic

State Energy ↑ Endothermic

↗ Deposition

Freezing ↗

Solid

↙ Melting

↙ Sublimation

Liquid

Condensation ↗

↙ Vaporization

Gas

http://www.chemistry.wustl.edu/~edudev/LabTutorials/Thermochem/Fridge.html

Read the Chapter 4 Summary on Page 68.

By Jawad Ahmad

Chapter 5 The Atom 5.2 Improvements to the Atomic Model

Ernest Rutherford theorized that electrons travel around the nucleus. The problem with this idea is that electrons, which are negatively charged, would eventually lose energy, slow down, and fall into the nucleus of the atom where it is attracted to the positively charged protons.

Bohr’s Atomic Model

Niels Bohr theorized that electrons revolve/move around the nucleus in circular orbits that are a fixed/specific distance from the nucleus. The amount of energy the electron has depends on the distance it is from the nucleus. The electron in an atom has more energy the farther away it is from the nucleus. The electron does not lose any energy while traveling around the nucleus.

Bohr’s Model was based on the work of Max Planck. Planck theorized that energy levels were not continuous but discrete. Because of this theory Bohr theorized that the electron could only be in specific orbits around the nucleus.

Bohr’s Evidence

When a photon γ with enough energy hits an electron in an atom the electron will move to a higher energy level (orbit/radius) in an excited atom. This is called photon absorption.

After a short time the electron will move back to its original position/orbit/radius. The energy lost by the electron will leave as a photon γ. This is called photon emission.

http://astrocosmosci.files.wordpress.com/2012/07/photon-emission-absorption.jpg

In an experiment by Johann Jakob Balmer, hydrogen gas was sealed in a tube and a current was given to the hydrogen gas to excite it. The hydrogen gas then produced light. When this light is passed through a slit vertical lines called emission spectrum lines are visible. These emission spectrum lines are specific/unique to each element and are the elements fingerprints.

By Jawad Ahmad

Principal Energy Levels and Sublevels

There are seven principal energy levels, or orbits. Niels Bohr suggested that the principal energy levels may have sublevels, labeled s, p, d, and f.

The s sublevel can hold up to two electrons, the p sublevel can hold up to six electrons, the d sublevel can hold up to ten electrons, and an f sublevel can hold up to 14 electrons.

http://chemwiki.ucdavis.edu/Inorganic_Chemistry/Electronic_Configurations

Chadwick’s Contributions

The mass of an atom was measured to be much higher than expected. James Chadwick found that the nucleus of the atom contains a particle with no charge. This particle is named the neutron and has a mass that is slightly greater than the mass of a proton.

The new model of the atom has neutrons and protons at the center of the atom and electrons outside the nucleus moving in discrete circular orbits.

Modern Atomic Theory

Scientists now had to find the exact distance the electrons are from the nucleus. This is very difficult to do since the atomic nucleus and electrons are so small. Finding the exact location/position of an electron will change its velocity. Finding the exact velocity of an electron will change its location/position. Because of this it is impossible to know the exact location and velocity of an electron. Because of this we draw an electron cloud to tell us the possible location an electron can be.

By Jawad Ahmad

5.3 Properties of Subatomic Particles

Atoms are made up of electrons, neutrons, and protons. Atomic Size

We have never seen an atom because the diameter of an atom is smaller than the wavelength of visible light. The diameter of an atom is about 2 × 10−10 m = 0.2 nm. We can only see objects that are longer than the wavelength of visible light.

Since we cannot see an atom directly we need to use alternative/other methods to understand the shape of an atom. A scanning tunnel microscope uses an electronic surface to scan a surface. See Figure 5.15 on page 84.

Atomic Number

The atomic number, or the number of protons in an atom, is the definition of an element.

Hydrogen will always have one proton, helium will always have two protons, lithium will always have three protons, etcetera.

Atoms are electrically neutral, meaning that the total charge of an atom is 0 coulombs. This means that the number of protons is equal to the number of electrons in an atom.

Isotopes

Hydrogen will always have one proton. Sometimes hydrogen is found with zero neutrons (H-1), sometimes hydrogen is found with one neutron (H-2), and sometimes hydrogen is found with two neutrons (H-3).

Atoms with the same number of protons and different number of neutrons are isotopes of each other. See Figure 5.17 on page 85.

Mass Number

The mass number of an atom is the number of neutrons plus the number of protons in an atom.

The atomic notation tells us the name of the atom (chemical symbol), how many protons are in the atom (atomic number), and the number of neutrons plus protons (mass number) in the atom.

The atom Au19779 is gold with 79 protons and 197 neutrons plus protons. It doesn’t matter if

the smaller number is on the top or bottom. The larger number is always the number of neutrons plus protons (mass number) and the smaller number is always the number of

protons (atomic number), so Au19779 = Au79

197 .

We can find the number of neutrons in an atom by subtracting the atomic mass from the mass number.

Atomic Mass

The atomic mass unit has replaced the kilogram in atomic mass measurements since the mass of an atom is small and people don’t like to calculate small numbers.

The atomic mass is the average mass of a naturally occurring element.

By Jawad Ahmad

Chapter 11 Nuclear Chemistry 11.1 Radioactivity

Question: What is radioactivity?

Radioactivity occurs/happens when an unstable atom emits (give off) particles and energy. The Nucleus

Question: How are protons and neutrons held together in the nucleus?

Answer: Protons and neutrons are held together in the nucleus by the strong 𝐟 𝐨𝐫𝐜𝐞. The

strong f orce has a very short range/distance. As the distance increases the strong f orce decreases.

At short distances the strong f orce is stronger than the electromagnetic f orce. At longer

distances the electromagnetic f orce is stronger than the strong f orce. Forces and Stability

The strength of the strong f orce decreases as the number of protons in the nucleus increases. Because of this more neutrons are in atoms with a large number of protons.

The red line on Figure 11.2 on page 178 is called the “Band of Stability.” This is the neutron to proton ratio that gives stable atoms. Atoms outside this red line are unstable/radioactive.

Unstable/unbalanced atoms want to decay. Radioactive decay is when an unstable nucleus spontaneously/suddenly emits matter and energy. A nucleus is unstable when the neutron

to proton ratio is outside the band of stability and when the strong f orce is not great enough to hold the nucleus together.

Radioactive Decay

All elements with 84 or more protons decay. That means they are all radioactive.

Uranium has 92 protons.

Transuranium elements are elements with 93 or more protons. They are all unstable and are rarely found in nature. They are made in laboratories and decay/decompose almost immediately/instantaneously after they are formed/created.

All elements have radioactive isotopes. It depends on its neutron to proton ratio. Isotopes and Radioisotopes

Isotopes are atoms with the same number of protons but different number of neutrons.

Radioisotopes are isotopes that are unstable and decay.

All elements have isotopes and some of these are radioisotopes.

All isotopes of an element have the same chemical properties. Describing Nuclei

The atomic number is the number of protons in the nucleus of an atom.

The mass number is the total number neutrons plus protons in an atom.

Example: In C612 , C is the chemical symbol, 6 is the atomic number, and 12 is the mass

number. The above chemical symbol can also be written as C126 . Just remember that the

smaller number is the number of protons in the nucleus and that the larger number is the number of neutrons plus protons in the nucleus.

11.2 Nuclear Decay and Radiation

Chemical Reactions involve changes in electron number. Mass is conserved.

Nuclear Reactions involve changes in nuclei. Mass is not conserved. Some mass will convert to energy.

In both chemical and nuclear reactions the reactants are on the left side and the products are on the right side of the equation. Example: A + B C. Both A and B are reactants while C is a product.

By Jawad Ahmad

Nuclear Radiation Alpha α Particles

An alpha α particle is the nucleus of the helium atom. An alpha α particle has two protons and two neutrons. It has a charge of +2. In nuclear equations an alpha α particle is shown as He2

4 . Example: U92238 → Th90

234 + He24

Beta β Particles

A beta β particle is an electron. In nuclear equations a beta β particle is shown as e−10 .

Example: I53131 → Xe54

131 + e−10 . In β decay, a neutron becomes a proton and an electron

leaves the atom. Gamma γ Rays

A gamma γ ray is high energy electromagnetic radiation. A gamma ray has much more energy than visible light (See Figure 21.7 on page 357.). A gamma ray is not a particle because it has no mass or electric charge. Gamma γ rays are commonly emitted with alpha

and beta particles during nuclear decay. Example: Th90230 → Ra88

226 + He24 + γ

Penetrating Power

Question: Why do you have to wear a heavy shirt when you get an x-ray at the hospital?

Alpha α particles are easy to stop. Gamma γ rays are the most difficult to stop. The cost to stop a gamma γ ray is much greater than to stop an alpha γ particle or beta β particle. See Figure 11.6 on page 181.

Transmutation

Transmutation is the process in which one element changes into another element through nuclear decay.

Sometimes a radioactive element will go through many decays before become stable. See Figure 11.7 on page 182.

In artificial transmutation fast moving particles hit the nucleus of an atom to form new elements. All the transuranium elements have been created by artificial transmutation.

Half-Life

The half-life of a radioisotope is the time it takes for one-half of the atoms to decay (or convert to energy).

mfinal

minitial= (

1

2)n

where mfinal is the final mass of the radioactive object, minitial is the initial mass of the object, and n is the number of half-lives that have been completed on the object. See Figure 11-8 on page 183.

11.3 Nuclear Reactions and Their Uses Nuclear Fission

Nuclear Fission occurs/happens when a big atom breaks/decays into smaller atoms. Mass and Energy

Mass is not conserved in nuclear fission. The total mass of the large atom before the reaction is greater than the total mass of the two smaller atoms after the reaction. The missing mass is converted to energy. This is why nuclear reactions are much more powerful than chemical reactions. See Figure 11-9 on page 184.

Chain Reactions

In a chain reaction, the first action is linked/connected to the next action. See Figure 11.10 on page 185.

A nuclear explosion will occur/happen if there is an uncontrollable nuclear chain reaction in a large mass of material. A lot of energy can be created from this and nuclear power plants use fission reactions to produce electricity.

By Jawad Ahmad

Nuclear Power Plants

Nuclear power plants produce a large amount of electricity without polluting air (unlike coal or gas) or water.

Unfortunately nuclear power plants produce radioactive waste that has a half-life of thousands of years.

Nuclear Fusion

Nuclear Fusion occurs/happens when two small mass atoms combine to form/create one large mass atom. The total mass of the two small atoms before the reaction is greater than the total mass of the one larger atom after the reaction. The missing mass is converted to energy. See Figure 11.12 on page 186.

Nuclear fusion produces more energy than nuclear fission. Temperature and Fusion

To get two nuclei to combine is very difficult because of the electric repulsion (Repel is the opposite of attract.). This can only happen if the two small atoms are traveling at high speeds. These high speeds only happen when the temperature is great (like millions of degrees). This great temperature only occurs/happens in stars.

Solar Fusion

The fusion reaction in the sun (which is a star) occurs in several steps.

Each second the sun (which is a star) will fuse 600 million tons of hydrogen into 596 million tons of helium. The missing 4 million tons of matter is converted to energy.

Fusion Reactions on Earth

A fusion power source would be ideal/perfect/best since it would not pollute the air and the waste will be minimal/smallest.

Unfortunately only short-lived fusion reactions have been produced here in laboratories on Earth.

Detecting Radiation

Unfortunately we can’t see, hear, smell, taste, or feel/touch radiation.

To minimize radiation we have to minimize our time next to a radioactive source, maximize our distance from a radioactive source, and put something between us and the radioactive source. This is called time, distance, and shielding.

People use film badges, Geiger counters, and electronic sensors to detect and measure radiation.

Nuclear Medicine

Cancer cells can be destroyed by exposing it to radiation. Unfortunately this kills both healthy and unhealthy cells.

Radioisotopes can be used as tracers to image parts of the human body. See Figure 11.14 on page 187.

Nuclear Storage Tank in Washington is Leaking Radioactive Waste http://www.businessinsider.com/nuclear-storage-tank-in-washington-is-leaking-radioactive-waste-2013-2#ixzz2L8jrpLDN

By Jawad Ahmad

Chapter 12 What is Motion? 12.1 Measuring Motion

Every object that is at rest on Earth is actually moving 30 km/s relative to the sun. Your speed depends on who is watching you.

Motion and Position

The position of an object is the location of an object.

An object is in motion when it changes its position/location. Reference Point

The reference point is the location where you are making a measurement. Example: The car is going 60 km/hr relative to the man at rest on the ground. The man at rest on the ground is the reference point.

Relative Motion

Relative motion is the speed and direction of an object with respect to another object. Example: A man at rest on the ground sees a plane flying 500 km/h while the plane (which feels like it is at rest) sees the man running at -500 km/h.

Displacement

The distance is the Σ length an object moves (scalar: # only).

The 𝐝 isplacement is the length and direction an object moves (�⃑� ector: # and direction). The

length of the 𝐝 isplacement is the difference between the final location and the initial/beginning location.

See Figure 12-4 on page 195. Speed Average Speed

The average speed of an object is the Σ distance an object travels divided by the Σ time it takes to travel that distance. The units of average speed are [distance/time].

Instantaneous Speed

The instantaneous speed of an object is the speed at an exact moment/time. Example: The speedometer in a car. See Figure 12.5 on page 196.

Graphing Motion

The slope of a line is the change in the y distance divided by the change in the x distance.

slope = m =∆y

∆x=

yfinal − yinitial

xfinal − xinitial

If the x-axis on a graph represents the time it takes an object to travel and the y-axis on a graph represents the distance an object travels then the slope of a line on the graph is the speed of the object. The greater the slope the greater the speed of the object. See Figure 12-6 on page 197.

By Jawad Ahmad

12.2 �⃑⃑� 𝐞𝐥𝐨𝐜𝐢𝐭𝐲 and �⃑⃑� 𝐜𝐜𝐞𝐥𝐞𝐫𝐚𝐭𝐢𝐨𝐧

�⃑⃑� 𝐞𝐥𝐨𝐜𝐢𝐭𝐲

The v⃑ elocity of an object gives the speed and direction of an object. V⃑⃑ elocity is a vector, meaning it has both a number and direction.

v⃑ elocity = v⃑ =∆ d⃑ isplacement

∆ time=

d⃑ final − d⃑ initial

tfinal − tinitial= [distance/time]

Since the above equation is a v⃑ ector we can break it up into three parts:

vx =∆dx

∆t=

dx f − dx i

tf − ti

vy =∆dy

∆t=

dy f − dy i

tf − ti

vz =∆dz

∆t=

dz f − dz i

tf − ti

Adding �⃑⃑� 𝐞𝐥𝐨𝐜𝐢𝐭𝐢𝐞𝐬

You can add or subtract two velocities when one object is on top of the other and the two objects move in the same or opposite direction. Example: See Figure 12-8 on page 198.

�⃑⃑� 𝐜𝐜𝐞𝐥𝐞𝐫𝐚𝐭𝐢𝐨𝐧

A change in the v⃑ elocity of an object is called a⃑ cceleration. a⃑ ≠ 0 m

s2 when you speed ↑,

slow ↓ (deceleration), or Δ direction (since a⃑ cceleration is a v⃑ ector). Example: See Figure 12-9 on page 199 and Figure 12-11 on page 201.

Example: An object moving in a circle with a constant speed has a changing v⃑ elocity and a nonzero a⃑ ccereration.

Calculating �⃑⃑� 𝐜𝐜𝐞𝐥𝐞𝐫𝐚𝐭𝐢𝐨𝐧

a⃑ cceleration = a⃑ =∆ v⃑ elocity

∆ time=

v⃑ final − v⃑ initial

tfinal − tinitial= [

distance/time

time] = [distance/time2]


ax =∆vx

∆t=

vx f − vx i

tf − ti ay =

∆vy

∆t=

vy f − vy i

tf − ti az =

∆vz

∆t=

vz f − vz i

tf − ti

Graphing �⃑⃑� 𝐜𝐜𝐞𝐥𝐞𝐫𝐚𝐭𝐢𝐨𝐧

If the x-axis on a graph represents the time it takes an object to travel and the y-axis on a graph represents the speed of an object then the slope of a line on the graph is the a⃑ cceleration of the object. The greater the slope the greater the a⃑ cceleration of the object. See Figure 12-11 on page 201.

12.3 �⃑⃑⃑� 𝐨𝐦𝐞𝐧𝐭𝐮𝐦 �⃑⃑�

m⃑⃑⃑ omentum = p⃑ = mass × v⃑ elocity = m × v⃑ = [kg ∙ m

s]


px = m × vx py = m × vy pz = m × vz

The m⃑⃑⃑ omentum p⃑ of an object is directly proportional to its mass and v⃑ elocity.

Conservation of �⃑⃑⃑� 𝐨𝐦𝐞𝐧𝐭𝐮𝐦 �⃑⃑�

If there is only one external f orce on a group of objects then p⃑ initial = p⃑ final. See Figure 12.12 on page 202.

Collisions Between Objects

When two objects hit each other and there are no other external f orces on the two objects then m⃑⃑⃑ omentum p⃑ will transfer from one object to another. Example: Billiard balls. See Figure 12.13 on page 203.

By Jawad Ahmad

Chapter 13 Nature of 𝐅 𝐨𝐫𝐜𝐞𝐬

13.1 What is 𝐅 𝐨𝐫𝐜𝐞?

A 𝐟 𝐨𝐫𝐜𝐞 is a push or a pull. A f orce is a v⃑ ector (like v⃑ elocity and a⃑ cceleration) so it has both

a number and direction. The unit of f orce is the Newton.

Types of 𝐅 𝐨𝐫𝐜𝐞𝐬

A contact 𝐟 𝐨𝐫𝐜𝐞 is a f orce when two objects are touching each other. Examples: 1. A book on a table. 2. A man pushing a wall. 3. A ball rolling on the ground.

An action-at-a-distance 𝐟 𝐨𝐫𝐜𝐞 is a f orce when two objects are not touching each other. Examples: 1. If you jump up the Earth pulls you down even though you are not touching the Earth.

This is the f orce of gravity. 2. Two electrons repel each other even though they are not touching each other. An

electron and a proton attract each other. This is the electric f orce. 3. Two magnets can attract or repel each other even though they are not touching each

other. This is the magnetic f orce.

Combining 𝐅 𝐨𝐫𝐜𝐞𝐬

Because a f orce is a v⃑ ector, f orces add and subtract. See Figure 13.2 on page 208.

The net 𝐟 𝐨𝐫𝐜𝐞 of an object is the sum/total of all the f orces on an object.

Balanced 𝐅 𝐨𝐫𝐜𝐞𝐬

Balanced 𝐟 𝐨𝐫𝐜𝐞𝐬 are f orces on an object that add up to zero. This means that a⃑ = 0 m

s2 and

v⃑ = constant. Examples:

1. Pushing a book at rest. The f orce of the push on the book is equal in number/magnitude

but opposite in direction as the f orce of friction. F⃑ push + F⃑ friction = 0 N F⃑ push =

−F⃑ friction a⃑ = 0 m

s2 v⃑ = constant.

2. Pushing a book at a constant speed in a straight line. F⃑ push + F⃑ friction = 0 N F⃑ push =

−F⃑ friction a⃑ = 0 m

s2 v⃑ = constant.

Remember that for balanced f orces ∑ F⃑ ext = 0 N, a⃑ = 0 m

s2, and �⃑� = 𝐜𝐨𝐧𝐬𝐭𝐚𝐧𝐭. The object

can be at rest or moving in a straight line at the same speed if the f orces on it are balanced.

Unbalanced 𝐅 𝐨𝐫𝐜𝐞𝐬

Unbalanced 𝐟 𝐨𝐫𝐜𝐞𝐬 are f orces on an object that don’t add up to zero. Example: Pushing

horizontally on a book. If the f orce of the push on the book is greater than the f orce of

friction between the book and the table then we have an unbalanced f orce on the book.

F⃑ push + F⃑ friction > 0 𝑁 F⃑ push > −F⃑ friction a⃑ ≠ 0 m

s2 v⃑ ≠ constant

Balanced 𝐅 𝐨𝐫𝐜𝐞𝐬

∑F⃑ ext = 0 N

a⃑ = 0 m

s2

v⃑ = constant

Unbalanced 𝐅 𝐨𝐫𝐜𝐞𝐬

∑F⃑ ext ≠ 0 N

a⃑ ≠ 0 m

s2

v⃑ ≠ constant

By Jawad Ahmad

13.2 The 𝐅 𝐨𝐫𝐜𝐞 of Friction

The F⃑ friction resists motion on an object.

F⃑ friction always points opposite the direction of motion.

The F⃑ friction always slows an object down. Factors Affecting Friction

A rough surface has a high F⃑ friction while a smooth surface has a low F⃑ friction. Types of Friction

Static friction is the F⃑ friction of between an object at rest and the surface it is resting on.

Sliding friction is the F⃑ friction between a moving object and the surface it is moving on.

The static friction of an object is much greater than the sliding friction of an object.

Example: The F⃑ push needed to move a book at rest on a horizontal table is much greater

than the F⃑ push needed to move the same book if it’s already moving.

Fluid friction (viscosity) is the F⃑ friction of a fluid. A fluid can be a liquid or a gas.

Rolling friction is the F⃑ friction of a rolling object. The F⃑ friction of a rolling object is much less

than the F⃑ friction of a sliding object or a static object. Example: It takes much more f orce to move a heavy truck at rest than to keep the same truck moving if it is already moving.

Using Friction

Friction is helpful because it slows objects down. See Figure 13.7 on page 211. Reducing Friction

Friction can sometimes be bad because it will convert useful kinetic energy (or moving

energy) into useless heat. Air, oil, and ball bearings are all used to reduce the F⃑ friction between two objects. See Figure 13.8 on page 211.

By Jawad Ahmad

13.3 The 𝐅 𝐨𝐫𝐜𝐞 of Gravity The Study of Gravity

The F⃑ gravity is the attraction between two objects with mass.

Law of Universal Gravitation

Law of Universal Gravitation: The gravitational f orce = F⃑ gravitational =Gm1m2

r2 . G = 6.67 ×

10−11 N×m2

kg2 , m1 and m2 are the masses of the two objects, and r is the distance between

the two objects.

The gravitational f orce is directly proportional between the mass of the objects and inversely proportional to the distance between the two objects. Example: If you double the

distance between two objects, the F⃑ gravitational will decrease by 4.

Falling Objects For a falling object we have two cases:

1) When �⃑� = �⃑� : Free Fall

An object is in free fall if the object is in the air with the only external f orce being the f orce

of gravity F⃑ gravity.

There is no air f riction F⃑ friction when the object is in free fall.

In free fall the object can be moving up, down, or at any angle.

If you drop two objects with different masses from rest at the same height/elevation in free fall the two objects will reach the ground at the same time. See Figure 13.14 on page 216.

If you drop an object from rest in free fall on Earth the speed vs. time graph would look like this:

The speed of the object increases by 9.8 m/s every second. The slope of this graph gives you the a⃑ cceleration of the object which is 9.8 m/s2.

0

20

40

60

80

100

120

0 2 4 6 8 10 12

Speed (m/s) vs. Time (s) in Free Fall (No Air Friction)

By Jawad Ahmad

2) When �⃑⃑� < �⃑⃑� : Non-Free Fall (or Air Resistance)

Air resistance is the f orce of friction from air.

If an object is moving up on Earth both the F⃑ gravity and the F⃑ friction point down.

If an object is falling down on Earth the F⃑ gravity points down and the F⃑ friction points up.

The F⃑ friction of a falling object is directly proportional to the velocity of the object. As the

v⃑ elocity of an object increases so does the F⃑ friction. Example: When you stick your head out of the window of a fast moving car your head is pushed back more than when you stick your head out of the window of a slow moving car.

The terminal �⃑� 𝐞𝐥𝐨𝐜𝐢𝐭𝐲 of an object is when an object is falling down and the

magnitude/number of the F⃑ gravity down is equal to the magnitude/number of the F⃑ friction

up.

When an object reaches its terminal velocity, ∑ F⃑ y = 0 N, a⃑ y = 0 m

s2, and v⃑ = constant. See

Figure 13.15 on page 216.

The terminal v⃑ elocity of an object depends on size and shape of the object.

Example: An object falls from rest with F⃑ friction. As t ↑, v⃑ elocity ↑ and F⃑ friction ↑ also.

After some time F⃑ gravity = −F⃑ friction. ∑ F⃑ y = may = Ffriction + Fgravity = 0 N. a⃑ y =

0 m

s2. v⃑ y = constant = terminal v⃑ elocity.

Example: Compare the velocities of an object falling from rest with no air friction and with air friction. Graph the results.

0

20

40

60

0 2 4 6 8 10 12

Speed (m/s) vs Time (s) with Air Friction

𝐭 (𝐬)

Free Fall

(No 𝐅 𝐟𝐫𝐢𝐜𝐭𝐢𝐨𝐧) 𝐯𝐲 (𝐦/𝐬)

With 𝐅 𝐟𝐫𝐢𝐜𝐭𝐢𝐨𝐧

𝐯𝐲 (𝐦/𝐬)

0 0 0 1 9.8 9.8 2 19.6 19.6 3 29.4 29.4 4 39.2 38 5 49 45 6 58.8 50 7 68.6 52 8 78.4 52.3 9 88.2 52.4

10 98 52.4

By Jawad Ahmad

The slope of the above graph gives you the a⃑ cceleration of the object with air resistance. The slope of the graph (or the a⃑ cceleration) starts at 9.8 m/s2 and decreases to 0 m/s2.

When the a⃑ cceleration (or slope) is 0 m/s2 the v⃑ elocity is constant which is the terminal v⃑ elocity of the object.

Objects with less mass reach terminal v⃑ elocity quicker. Objects with more mass reach terminal v⃑ elocity at later times. Example: Example: An elephant, human, and ball are all dropped from rest at the same time. The elephant will reach the ground first. Then the human. Then the ball. The mass, shape, and the volume of the objects matter.

�⃑⃑⃑� 𝐞𝐢𝐠𝐡𝐭 Versus Mass

The mass is the amount of stuff an object has. Mass is a scalar so it has only a number and no direction. Mass has units of kilograms.

The �⃑⃑� 𝐞𝐢𝐠𝐡𝐭 of an object is the F⃑ gravity at the surface of a planet. W⃑⃑⃑ eight is a vector so it

has both a number and direction. The direction of w⃑⃑⃑ eight always points down towards the

center of the planet. W⃑⃑⃑ eight is a f orce so it has units of Newtons.

W⃑⃑⃑ eight = F⃑ gravity = m × g⃑ = [kg ×m

s2] = [Newton]

g⃑ Earth = 9.8 m

s2.

W⃑⃑⃑ eight changes from location to location but mass doesn’t. Your mass on Earth and your mass in space are the same. Your w⃑⃑⃑ eight on Earth and your w⃑⃑⃑ eight in space are different since g⃑ is different from Earth and space.

Doctors don’t know what they are talking about when they ask you for your w⃑⃑⃑ eight. Doctors should ask you for your mass. This is why the periodic table of elements has units of mass and not w⃑⃑⃑ eight.

Question: Is g⃑ = +9.8 m

s2 or g⃑ = −9.8 m

s2 on Earth?

Answer: g⃑ always points to the center of the Earth. If the +y axis is pointing up then g⃑ =

−9.8 m

s2. If the +y axis is pointing down then g⃑ = +9.8 m

s2.

By Jawad Ahmad

13.4 Newton’s Laws of Motion Newton’s First Law of Motion: The Law of Inertia

Inertia is the resistance to change in motion. Objects will not change their speed and

direction (or v⃑ elocity) unless there is an external f orce on the object.

The law of inertia states/says that an object at rest will be/remain at rest forever unless

there is an F⃑ external. A moving object will continue to move in a straight line with the same

speed forever unless there is an F⃑ external.

Example: A rock moving in space will move at the same speed in a straight line forever

unless there is an F⃑ external. A football on Earth will move at the same speed in a straight line

forever unless there is an F⃑ external. The reason why a football on Earth slows down and

stops is because of the F⃑ friction.

Objects do not like to change what they are doing unless there is an F⃑ external. An object will

speed ↑, slow ↓, or Δ direction if ∑ F⃑ external ≠ 0 N.

Inertia is directly proportional to the mass of the object. If mass ↑, then the inertia ↑. If mass ↓, then the inertia ↓.

Example: It’s better to fight a small person with a small mass than a larger person with a large mass because it’s easier to move the person with a small mass.

Example: If a small car and a large truck are moving at the same speed, it will take a longer distance for the large truck to stop than the small car because of the law of inertia. It’s harder to get heavier objects to stop/start moving than lighter objects.

In summary: For all objects, v⃑ elocity = constant and a⃑ = 0 m

s2 unless there is an F⃑ external.

For all objects, the v⃑ elocity will not change unless there is an F⃑ external.

Newton’s Second Law of Motion: The Law of �⃑⃑� 𝐜𝐜𝐞𝐥𝐞𝐫𝐚𝐭𝐢𝐨𝐧

The law of a⃑ cceleration states/says that the a⃑ cceleration of an object is directly

proportional to the sum of the external f orces on the object and inversely proportional to the mass of the object. An object will a⃑ ccelerate in the same direction as the net/total

f orce.

∑F⃑ ext = mass × a⃑ cceleration = m × a⃑ = [kg × m

s2 ] = [Newton] = [N]


∑Fx = m × ax ∑Fy = m × ay ∑Fz = m × az

∑ F⃑ ext always points in the same direction as a⃑ cceleration.

By Jawad Ahmad

Newton’s Third Law of Motion: The Law of Action and Reaction

The law of action and reaction states/says that if you have two objects the f orce of object 1

on object 2 is equal in magnitude/number and opposite in direction of the f orce of object 2

on object 1. Newton’s third law of motion needs/requires one f orce and two objects.

+F⃑ 1 on 2 = −F⃑ 2 on 1 +m1a⃑ 1 = −m2a⃑ 2

Examples of Newton’s 3rd law: 1. My hand punches your face. Your face punches my hand. 2. I hit your car. You hit my car. 3. Man pushes wall →. Wall pushes man ←. 4. Man pushes chair ↓. Chair pushes man ↑. 5. Feet push ground ←. Ground pushes feet →. 6. Tires push ground ←. Ground push tires →. 7. Fish pushes water ←. Water pushes fish →. 8. Foot kicks football →. Football kicks foot ←. 9. Rocket pushes exhaust gas ↓. Exhaust gas pushes rocket ↑. 10. Earth pulls man ↓. Man pulls Earth ↑.

Example: When you jump, the Earth pulls you down while you pull the Earth up. You cannot see the Earth move up but you do see yourself move down because the mass of the Earth is much greater than your mass. Because of this the a⃑ cceleration of the Earth is much less than the a⃑ cceleration of you:

+F⃑ 1 on 2 = −F⃑ 2 on 1

+F⃑ man on Earth = −F⃑ Earth on man +mmana⃑ man = −mEartha⃑ Earth

mEarth ≫≫ mman and a⃑ Earth ≪≪ a⃑ man mEarth ≈ 6 × 1024 kg

Newton’s second law of motion is about many f orces on one object. Newton’s third law of

motion is about one f orce on two objects.

By Jawad Ahmad

Chapter 15 Work, Power, and Simple Machines 15.1 Work & Power Work

You need energy to do work. Work is done when you move an object.

Work = f orce × d⃑ isplacement × cosθ = [Newton × meters] = [Joules]

where f orce is the push or pull of an object, d⃑ isplacement is the distance and direction the

object moves, and θ is the angle between the f orce and d⃑ isplacement. See Figure 15.4 on page 240.

Work is the transfer of energy. Work is a scalar so it has only a number and no direction (v⃑ ector × v⃑ ector = scalar).

Example: You only do work if you move an object. No work is done if I push a wall that does

not move since d⃑ isplacement = 0 m. If you push an object with an angle of the f orce as 0 degrees, 45 degrees, and 90 degrees, 0 degrees will give you the most work out of the energy you use (Example: Pushing a table horizontally.) and 90 degrees will give you no work (Example: Pushing a table down.).

Power

Power =work

time=

f orce × d⃑ isplacement × cos θ

time= f orce × v⃑ elocity × cosθ = [

Joule

s]

= [Watts] = [W]

where θ is the angle between the f orce and the v⃑ elocity of the object.

Power is a scalar since v⃑ ector × v⃑ ector = scalar.

From the above equation since time is on the denominator the power ↑ as work is done faster.

By Jawad Ahmad

Chapter 16 Nature of Energy 16.1 What is Energy? Energy Makes Everything Happen

Question: What is energy?

Answer: Energy is the “stuff” or “thing” that we need to do work.

Question: What is work?

Answer: Work is done when we move an object.

Work = f orce × d⃑ isplacement × cosθ = [Newton × meters] = [Joules] We need energy to do work.

Most of the energy from Earth comes from the Sun. Energy Units

Both energy and work have units of Joules. Since they both have the same units they are very closely related to each other but they are not the same.

Kinetic Energy

The energy of a moving object is called kinetic energy.

Kinetic Energy = KE =1

2mv⃑ 2 = [kg

m2

s2] = [Joules] ≥ 0 Joules

where m is the mass of the object in kilograms and v⃑ is the v⃑ elocity of the object in meters per second.

KE is directly proportional to the mass and velocity of the object. If you double the mass of an object, the KE ↑ by 2. If you double the velocity of an object, the KE ↑ by 4.

KE is a scalar since v⃑ ector × v⃑ ector = scalar. Potential Energy

The potential energy of an object is the energy stored/kept when an object moves against a

f orce. Examples: bow & arrow, spring, rubber band, fossil fuels (chemical potential energy), electric batteries (electrical potential energy), and food (chemical potential energy).

Gravitational potential energy is the energy of an object depending on its vertical position.

Gravitational Potential Energy = GPE = mg⃑ y⃑ = [kgm

s2m] = [Joule]

where m is the mass of the object in kilograms, g⃑ is the a⃑ cceleration from g⃑ ravity in meters per second squared, and y⃑ is the vertical distance of the object in meters.

GPE can be positive, 0, or negative. GPE is the energy of an object with respect to its location. GPE is directly proportional to the mass and vertical position of the object.

Forms of Energy Thermal Energy

Thermal energy is related to the movement or KE of particles. Chemical Energy

Chemical energy is the PE stored/kept in the bonds between atoms of a substance. Example: Plants and sugars. People eating food.

Electrical Energy

Electric potential energy is generated/created when electrons are forced together. Electrical energy is energy that arises/comes from the movement of electric charges.

Radiant Energy

Radiant energy is energy that comes from electromagnetic waves.

Memorize Figure 16-6 on page 266. As you go from left to right on the figure the energy of the wave increases.

From Figure 16-6 we see that x-rays have high energy so they should not be taken regularly. Gamma rays also have high energy so they will go through your body easily just like x-rays.

By Jawad Ahmad

Nuclear Energy

Nuclear Energy is the energy stored/kept in the nucleus of an atom. Nuclear energy holds the particles of the nucleus together. Example: Fission & fusion releases nuclear energy.

16.2 Energy Conversions

Energy is always being converted from one form/type to another. Example: A falling object converts GPE to KE. Plants convert radiant energy to chemical energy. People convert chemical energy to kinetic energy when they run.

Kinetic and Potential Energy Conversions

The kinetic energy (KE =1

2mv⃑ 2) and gravitational potential energy (GPE = mg⃑ y⃑ ) of an

object can change from one form/type to another. For example, a falling object will convert GPE to KE and a rising object will convert KE to GPE. See Figure 16-8 on page 267. If there is

no f orce of friction,

Mechanical Energy = KE + GPE =1

2mv⃑ 2 + mg⃑ y⃑ = Constant

Unfortunately/sadly most energy is lost as heat.

Read the last paragraph on page 267. Conservation of Energy

The law of conservation of energy states/says that energy cannot be created or destroyed. Energy can only Δ/change form/types. Energyinitial = Energyfinal

Don’t Read Machines as Energy Converters on Page 270 16.3 Energy Resources

Energy resources are energy sources that are used to meet the needs of the people. Making Electricity

KE or PE of a resource can be converted to electricity. There are several steps needed to convert KE or PE to electricity. Some energy is lost after each step. See Figure 16-14 on page 271.

Energy Resources from the Sun

A renewable resource cannot be used up. See page 272. Examples: solar, wind, hydroelectric, biomass

Solar Energy

Solar energy is energy that comes directly from the sun.

Solar energy is free but solar cells are expensive and inefficient. Wind Energy

No energy plant is necessary for wind energy and no pollution is created. Wind energy is useful only in cleared places where there is wind. The KE of wind is converted to electrical energy.

Hydroelectric Energy

Water flows/moves through a dam and spins a turbine which generates/makes electricity.

Hydroelectric energy is efficient and creates no pollution but a flowing river is needed. Biomass

Plant tissues used for fuel/energy are biomass fuels.

Biomass can be burned to heat homes.

Biomass can be converted to fuel/petroleum. Example: soy biodiesel.

Biomass is inexpensive to grow but causes air pollution when you burn it. Fossil Fuels

Fossil fuels are energy resources that are from ancient/old biomass remains.

Coal, natural gas, and petroleum are all popular forms/types of fossil fuels.

Fossil fuels produce/make a lot of the air and water pollution on Earth.

Fossil fuels are examples of a nonrenewable resource. A nonrenewable resource can be used up. Example: fossil fuels, fission & fusion, and geothermal energy.

By Jawad Ahmad

Energy from Atoms

The strong force in the nucleus of the atom which holds the neutrons and protons together can release a lot of energy when nuclear fusion and nuclear fission occur.

No pollution is created during nuclear fission but radioactive waste is created.

Nuclear fusion occurs/happens in stars. We have not learned to control nuclear fusion. Energy from Earth

Electricity can be generated/made using the heat from the Earth’s core/middle. This is called geothermal power.

A geothermal power plant is located where hot rocks lie just below Earth’s surface.

The hot rocks convert water to steam and the steam powers a generator.

Geothermal energy is nonrenewable but there is a lot of it.

No pollution is produced by geothermal power plants and the cost to make electricity from it is inexpensive.

There are not a lot of locations where hot rocks are near the Earth’s surface. 16.4 Energy Choices

Energy is being used more and more every day. Engineers have to find clean and inexpensive ways to get useful energy and save energy.

Fossil Fuel Problems

Fossil fuels (like petroleum, coal, and natural gas) are nonrenewable energy sources.

It is getting more expensive to extract (take out) fossil fuels.

The burning of fossil fuels creates air pollution.

Mining coal is dangerous and many people die every year from this. Energy Alternatives

Every energy resource has its benefits and hazards. See Figure 16.21 on page 276. Conservation Options

Energy conservation is being used to reduce the amount of energy people use.

Conserving energy reduces pollution and saves money. See Figure 16.22 on page 277.

You can reduce, reuse, and recycle to save energy.

𝐟 𝐨𝐫𝐜𝐞 ≠ 𝐞𝐧𝐞𝐫𝐠𝐲 ≠ 𝐰𝐨𝐫𝐤 ≠ 𝐩𝐨𝐰𝐞𝐫

A f orce is a push or a pull. F⃑ orce is a v⃑ ector and has the units of Newton’s.

Energy is something we need to do work. Energy is a scalar and has the units of Joules.

Work (Work = f orce × d⃑ isplacement × cos θ) is done when we move an object. Work is a scalar and also has the units of Joules.

Power (Power =work

time=

f orce×d⃑⃑ isplacement×cosθ

time= f orce × v⃑ elocity × cosθ) depends on

how fast we move an object. Power is a scalar and has units of Watts. Fattest Countries in the World Revealed: Extraordinary Graphic Charts the Average Body Mass Index of Men and Women in Every Country (with Some Surprising Results) http://www.dailymail.co.uk/health/article-2301172/Fattest-countries-world-revealed-Extraordinary-graphic-charts-average-body-mass-index-men-women-country-surprising-results.html#ixzz2Qhro3dCb The Health Effects of Drinking Soda http://www.ionizers.org/soft-drinks.html

By Jawad Ahmad

Chapter 19 Waves and Energy 19.1 The Nature of Waves Waves and Vibration

Question: How are waves created?

Answer: Vibrations (Something moving back and forth.) produce waves that carry energy. All waves are created from vibrations. A wave is a repeating disturbance traveling through matter or space. Example: See Figure 19-1 on page 316.

Waves and Energy

Since waves carry energy, they do work (work = f orce × d⃑ isplacement × cos θ). Example: A boat/canoe at rest in a lake moves when a wave goes under it. When the boat moves the wave loses energy. See Figure 19.3 on page 317.

Waves and Matter

Waves transfer energy but not matter. Example: A water wave or a rope moving up and down. See Figure 19.3 on page 317.

Mechanical Waves

Mechanical waves travel through matter.

A medium is the matter in which the mechanical wave travels through.

Example: Sound waves travel through air. The sound wave is a mechanical wave and the air is the medium in which it travels through.

Example: Ocean waves and water. The ocean wave is a mechanical wave and the water is the medium in which it travels through.

Example: A rope. A rope is a mechanical wave because it uses a rope as a medium to travel.

In space there is no sound because space is a vacuum. A vacuum has no matter. Electromagnetic Waves

Electromagnetic waves can travel/move through vacuum and matter. Example: See Figure 21.7 on page 357.

Example: In space we can’t talk to each other (using sound waves) but we can text message each other (using electromagnetic waves).

19.2 Types of Waves Transverse Wave

In a transverse wave the vibration is at right angles (perpendicular) to the direction in which the wave travels. Example: All electromagnetic waves (See Figure 21.7 on page 357.) and some mechanical waves like water.

See Figure 19.5 on page 319. The rope moves up and down and the wave moves to the right. Understand what the crest/peak and trough/valley are. The peaks and valleys of the rope are equal to the peak and valley of the hand (or cause/source).

Compressional/Longitudinal Wave

In a compressional/longitudinal wave the vibration is parallel to the direction in which the wave travels. See Figure 19.6 on page 320. Example: Sound waves.

See the compression and rarefaction in Figure 19.9 on page 322. Sound Waves

Sound is a compressional/longitudinal wave.

See the compression (many particles are close together) and rarefaction (many particles are far apart) regions/areas in Figure 19.7 on page 321.

Seismic Waves

An earthquake is called a seismic wave. A seismic wave is both a transverse wave and a compressional/longitudinal wave. See Figure 19.8 on page 321.

By Jawad Ahmad

19.3 Properties of Waves The Parts of a Wave

Figure 19.9 on page 322 shows the difference between compressional/longitudinal and transverse waves.

Wavelength

The wavelength λ (λ is the Greek letter lambda) of an object is the distance between two identical/similar points on a wave.

wavelength = λ = [m] See Figure 19.10 on page 323.

Frequency

The frequency of an object is the number of cycles/wavelengths that passes through a point each second.

frequency = f =# cycles

1 second= [

1

seconds] = [Hertz] = [Hz]

Example: A computers processing speed has units of hertz. Frequency and Period

The period of a wave is the time it takes a wave to complete one cycle/wavelength.

Period =# seconds

1 cycle= [second]

The period of a wave is the inverse of the frequency.

frequency =1

period period =

1

frequency

Example: Draw a picture describing frequency and period. Frequency and Wavelength

See Figure 19.11 on page 324. If you move your hand up and down faster, the wavelength ↓ and frequency ↑. Since the frequency ↑, the period ↓. The wavelength and frequency of a wave are inversely proportional to each other. The fhand = fwave.

Wave Speed

Question: Do you see or hear lightning first? Why?

Answer: Lightning is seen first and then heard. The speed of light is much faster than the speed of sound.

For sound waves: speedsolid ≫ speedliquid ≫ speedgas ≫ speedvacuum.

Example: The speed of sound in steel is about 5,100 m/s. The speed of sound in water is about 1,400 m/s. The speed of sound in air is about 340 m/s. The speed of sound in a vacuum is 0 m/s.

As temperature ↑ the speed of sound ↑ also.

For light/EM waves: speedvacuum ≫ speedgas ≫ speedliquid ≫ speedsolid

The speed of a wave is determined by the medium it travels through. wavespeed = frequency × wavelength

ν = f × λ Amplitude

The amplitude of a wave is directly proportional to the energy of the wave. Example: See Figure 19.3 and 19.14 on page 326.

By Jawad Ahmad

Chapter 20 Sound 20.1 The Nature of Sound Sound Waves

Sound waves are compressional/longitudinal waves. How Sound Waves Form

Vibrating objects have kinetic energy KE =1

2mv2 and creates regions/areas of compression

and rarefaction. Energy is transferred by this. How Sound Waves Travel


Sound waves reflect and diffract/bend. Sound Waves in Different Mediums

Sound is a mechanical wave so it cannot travel in a vacuum like electromagnetic waves.

For sound waves: speedsolid ≫ speedliquid ≫ speedgas ≫ speedvacuum. Example: The

speed of sound in steel is about 5,100 m/s. The speed of sound in water is about 1,400 m/s. The speed of sound in air is about 340 m/s. The speed of sound in a vacuum is 0 m/s.

The Speed of Sound

Sound travels by transferring energy by collisions. Speed and Elasticity

Elastic objects can bend/distort and return to its original shape/form.

The speed of sound is high in elastic materials because particles in elastic objects are very close together. This means that energy is transferred easily and quickly from one area/region to another. Energy is transferred with little loss.

Speed and Temperature

As temperature ↑ the speed of sound ↑ also. This is because hotter particles move faster and transfer energy quicker than colder particles.

20.2 Properties of Sound Frequency and Pitch

The pitch of a sound is how high or low the sound seems to be. The pitch of a sound is

directly proportional to the frequency (frequency =# cycles

second= [

1

second] = [Hz]). See Figure

20.5 and 20.6 on page 338. Amplitude, Energy, Intensity, and Loudness

Question: When you increase the volume the frequency of the sound wave is the same. What changes?

Answer: The energy of the sound wave. Energy

The amount of energy in a wave is directly proportional to the amplitude of the wave.

The more particles that are in a wave the larger its amplitude and the more energy it has.

It’s easier to see the compression and rarefaction regions/areas in a high amplitude sound wave than a low amplitude sound wave. See Figure 20.7 on page 339.

As the density (density =# particles

volume) of particles increases so does the waves energy.

By Jawad Ahmad

Intensity

The intensity of a wave is the amount of energy that passes through an area.

Intensity =Energy

Area= [

Joules

m2 ]

A shout will produce a high intensity and high energy sound wave that can be heard from a far distance.

A whisper will produce a low intensity and low energy sound wave the can be heard from only a short distance.

Sound waves travel through collisions. After each collision some energy is lost. A shout has more initial energy than a whisper. This is why a shout can be heard from a longer distance than a whisper.

Loudness

Loudness is the human perception/opinion of sound intensity. Loudness is directly proportional to the intensity of the sound wave.

A Scale for Loudness

The decibel dB is the unit for sound intensity.

Anything less than 0 dB cannot be heard by humans. This is the threshold for human hearing.

The average speaking voice is about 60 dB.

A 10 dB sound is 10 times greater in intensity than a 0 dB sound.

A 20 dB sound is 10 times greater in intensity than a 10 dB sound and 100 times greater than a 0 dB sound.

Hearing damage occurs at 85 dB and greater. Hearing damage is permanent and irreversible! No medicine or surgery can fix hearing damage!

The Doppler Effect

The Doppler effect occurs when you are moving toward or away from an object that is making noise.

If you are moving toward an object that is making noise the wavelength (length of a wave) of the sound will decrease and the frequency (number of cycles that pass a point per second) will increase.

If you are moving away from an object that is making noise the wavelength of the sound will increase and the frequency will decrease.

If both you and the sound source are not moving the wavelength and frequency of the sound will not change.

http://www.physicsclassroom.com/class/waves/u10l3d.cfm

A moving sound source or a moving listener produces the Doppler effect.

By Jawad Ahmad

Echoes

An echo is a reflected sound wave.

Sonar (SOund Navigation And Ranging) uses reflected sound waves to measure distances. See Figure 20.10 on page 342.

Don’t Read Beats on page 342 Chapter 21 Light and Other Electromagnetic Waves 21.1 What is an Electromagnetic (EM) Wave? Describing Electromagnetic Waves

EM waves can travel/move in a vacuum and in matter. Mechanical waves (like water and sound) can travel/move in matter only.

Examples of EM waves are microwaves used by mobile phones, radio waves used by radar speed guns (See Figure 21.1 on page 353), light we see, and the warmth we feel from the sun.

Vibrating Source

EM waves form when charged particles (like electrons or protons) vibrate. Waves in Space

Because vibrating electrons in matter are everywhere so are EM waves.

Most EM waves are not seen or felt by people (See Figure 21.7 on page 357). How Electromagnetic EM Waves Form

All EM waves have electric and magnetic fields. Force Fields

Figure 21.2 shows three types of action at a distance f orces. These f orces don’t need to touch an object to push or pull it and can exist in a vacuum.

Electric and Magnetic Fields

An electric charge (like an e- or p+) that is not moving produces only an electric field.

A moving electric charge (like an e- or p+) produces both an electric field and a magnetic field (See Figure 21.3 on page 354). A changing magnetic field produces a changing electric field. Changing electric and magnetic fields form EM waves.

EM Wave Formation

An EM wave develops when an electric charge vibrates. This vibration creates both a changing electric field and a changing magnetic field (See Figure 21.4 on page 355). A changing electric field generates/creates a changing magnetic field and a changing magnetic field generates/creates a changing electric field.

Properties of EM Waves

All matter contains charged particles. Since all charged particles are vibrating, they all give off (or emit) EM waves.

Frequency and Wavelength

The frequency of the oscillating/moving charge is equal to the frequency of the frequency of the EM wave.

Wave Speed

For light, speedvacuum > speedgas > speedliquid > speedsolid. See Figure 21.5 on page

356.

All EM waves travel/move at about 3 × 108 𝑚

𝑠 in a vacuum. This is called the speed of light.

Don’t Read The Dual Nature of Waves and Particles on page 356.

By Jawad Ahmad

21.2 The EM Spectrum Classifying Waves

Memorize Figure 21.7 on page 357. This is the EM spectrum. As you go from left to right in the picture, the frequency of the wave increases, the energy of the wave increases, and the wavelength of the wave decreases.

Speed, Wavelength, and Frequency speed = wavelength × frequency = λ × f

From the above equation if the speed of a wave is constant, as the λ ↓, f ↑. This is an inverse relationship. Energy ∝ frequency so high frequency waves (like gamma rays) have greater energy than lower frequency waves.

Radio Waves

A radio wave has a length that can range from a football to a football field. It has the longest wavelength and lowest energy in electromagnetic spectrum.

Low energy radio waves are used by televisions, radios, and cellular phones. Sending and Detecting Radio Waves

An antenna oscillates/vibrates electric charges which creates an electromagnetic wave. This antenna sends a radio wave. Another antenna detects the radio wave.

Microwaves

Radio waves that have wavelengths between 1 mm (0.001 m) and 30 cm (0.3 m) are called microwaves. Microwaves are used by microwave ovens to heat food by vibrating water. Microwaves are also used by portable phones and cellular phones.

Radio Detecting and Ranging (Radar)

Bats use echolocation to locate objects. Echolocation is the broadcast and reception of sounds.

Radio detecting and ranging, or radar, is echolocation that is used in technology. We use radar to track/locate planes and weather fronts by using radio waves.

Infrared Waves

The warmth from sunlight is from infrared waves. Infrared waves have wavelengths from around 0.75 m to 0.001 m.

Infrared Subgroups

There are three groups of infrared waves: near-infrared, mid-infrared, and far-infrared.

Far-infrared have wavelengths that are close to microwaves. Sunlight is an example of far-infrared.

Near-infrared have wavelengths that are close to visible light. Television remote controls use near-infrared wavelengths.

Detecting Infrared Waves


Some animals can detect/notice/sense infrared waves.

Satellites use infrared waves to analyze/examine/study Earth’s surface. Visible Light

Visible light has wavelengths of about 0.0000004 m to 0.0000007 m.

Each color has a different wavelength. See Figure 21.13 on page 360.

When all the colors are present you get white light. The sun emits white light.

Few objects emit light. Most objects reflect light.

Plants use the red and blue wavelengths to create food by photosynthesis. Ultraviolet Waves

UV waves have enough energy to damage living cells and cause sunburn. See Figure 21.13 on page 360.

By Jawad Ahmad

Beneficial Uses

The human body uses UV energy to produce vitamin D.

Hospitals use UV waves to disinfect equipment.

Some materials emit visible light when struck/hit by UV waves. Police detectives use a powder and UV light to look for fingerprints.

The Ozone Layer

Ozone (O3) is found around 15 km above the Earth’s surface.

Ozone absorbs (takes in) harmful/bad ultraviolet (UV) waves like x-rays and gamma rays emitted by the sun. See Figure 21.14 on page 361.

Ozone molecules are constantly being created/formed and destroyed by UV waves. This is a natural process.

Chlorofluorocarbons (CFCs) destroy the O3 in the ozone layer. This is an unnatural process. See Figure 21.15 on page 361.

X-Rays, Gamma Rays, and Their Uses

X-rays have enough energy to pass through skin and muscle.

The shortest wavelength and highest energy EM waves are gamma rays.

X-rays are used to create images of the skeletal structure. See Figure 21.16 on page 362.

Gamma rays are used to treat some cancers. 21.3 Producing Light Types of Lighting

Objects that give out (or emit) light are luminous. The sun is luminous.

Objects that reflect light are illuminated. The moon is illuminated from the sun. Incandescent Lights

An incandescent light bulb produces light by heating a metal wire (which is usually tungsten). Most of the energy, about 90%, is lost as heat. Only about 10% of the energy produces light. See Figure 21.17 on page 363.

Fluorescent Lights

A fluorescent light bulb is a glass cylinder. The glass cylinder is coated/covered with phosphorus. Each end has an electrode. There is a low pressure gas inside the cylinder. When a current (See chapter 23.) is turned on the two ends heat up and emit electrons. The electrons hit the gas atoms in the tube. The gas atoms emit UV radiation. The phosphor coating absorbs the UV waves and reemits the energy as visible light. See Figure 21.18 on page 364.

Fluorescent light bulbs are energy efficient. Unfortunately there is mercury inside the cylinder.

Neon Lights

Neon lights use a clear glass cylinder/tube with a gas inside. Neon gas produces red light. See Figure 21.19 on page 364.

Tungsten-Halogen Lights

Tungsten-halogen lights are used when bright lights are needed.

A halogen gas, usually fluorine or chlorine, is inside a quartz tube with a tungsten filament.

Tungsten-halogen lights are used on movie sets, in underwater photography, and to light airport runways.

Light Emitting Diodes (LEDs)

An LED does not get hot and doesn’t have any filaments.

An LED is an energy-efficient and long-lasting device/object. See Section 26.1

By Jawad Ahmad

Light Amplification by Stimulated Emission of Radiation (Lasers)

A laser is a device/object that produces a narrow/thin beam/ray of coherent light. Coherent light waves all have the same frequency and travel/move with their crests and troughs aligned/organized. Laser light has a high amount of energy in a small area because the light does not spread out a lot when it travels. Laser light is not found in nature.

All other light is incoherent. Incoherent light has a range of frequencies. Their crests and troughs are not aligned. See Figure 21.21 on page 365.

Lasers are used for cutting and welding objects, surveying and ranging, communication and data transmission, and corrective eye surgery.

http://www.physicsforums.com/showthread.php?t=182755

By Jawad Ahmad

Science Project Finds Plants Won't Grow Near Wi-Fi Router http://www.liveleak.com/view?i=cd3_1369428648#eOOWMh7OQKxVwcsA.99 New study links over 7,000 cancer deaths to cell phone tower radiation exposures http://www.naturalnews.com/040905_cell_phone_towers_radiation_cancer.html#ixzz2X3dmVqhJ Shocking New Cell Phone Radiation Study Reveals Increased Brain Tumor Risk for Children http://www.naturalnews.com/039419_cell_phone_radiation_brain_tumors_children.html#ixzz2NAAft4XR Mobiles Can Give You a Tumour, Court Rules http://www.thesun.co.uk/sol/homepage/news/4597109/Mobiles-can-give-you-a-tumour-court-rules.html#ixzz2F6ycHfhY Talented Musician Zapped to Death by Cell Phone Radiation http://www.naturalnews.com/038395_cell_phone_radiation_electrosensitivity_fatality.html#ixzz2FbsQwMcw Electromagnetic radiation damages DNA, disrupts the blood-brain barrier, weakens and damages sperm, and changes brain metabolism. Research in Motion sells the smartphone with the warning, "Do not keep near the pregnant abdomen."

http://hyperphysics.phy-astr.gsu.edu/hbase/emwav.html

By Jawad Ahmad

Chapter 23 Electric Charges and Currents 23.1 What is Electric Charge? Atoms and Electric Charge

Electricity is the movement of e-.

Atoms (like hydrogen, helium, lithium, copper, silver, and gold) are the basic building blocks of matter. They are all made up of p+, e-, and n.

An electrically neutral atom is an atom in which the number of p+ is equal to the number of e-.

An ion is an atom in which the number of p+ is not equal to the number of e-.

Electric 𝐅 𝐨𝐫𝐜𝐞𝐬

Similarly charged objects/particles (like two e- or two p+) repel each other. Oppositely charged objects/particles (like one e- and one p+) attract each other. (See Figure 23.3 on page 393.)

The electric f orce between two objects is

F⃑ electric =kq1q2

r2 ,

where k is a constant, q1 and q2 are the net/total charges of the two objects, and r is the distance between the two objects/particles. As the charge q1and/or q2 gets larger so does

the electric f orce between the two objects. As the distance r increases between the two

objects the electric f orce between the two objects decreases. This equation looks very similar to the gravitational force between two objects in which

F⃑ gravitational =Gm1m2

r2 .

The electric f orce and gravitational f orce are both action at a distance f orces. They both also exist in a vacuum.

Electric Fields

The electric field creates/makes an electric f orce in the area around an electric charge. See Figure 23.4 on page 394. Electric fields are perpendicular (90°) to the surface of the charged object. The electric field is stronger if you put a “test charge” closer to the object and weaker if you put a “test charge” farther away from the object.

Electric field lines always point from a positive charge to a negative charge. The arrow shows the direction in which a proton “test charge” would move.

By Jawad Ahmad

By Jawad Ahmad

http://www.physicsclassroom.com/class/estatics/u8l4c.cfm

23.2 Static Electricity What is Static Electricity?

Static electricity is the buildup of excess/extra charge on an object. This happens when the number of p+ is not equal to the number of e- in an object.

Electric discharge is the rapid/fast movement of e- from one place to another. See Figure 23.5 and 23.6 on page 395.

Charging Objects

Conduction happens/occurs when e- move along the surface of an object and on to other objects that are touching it.

A conductor is an object in which e- move through it easily. Examples of conductors are H2O and metals.

An insulator is an object that holds e- tightly and keeps them from moving easily. Examples of insulators are glass, air, plastic, rubber, and wood.

Induction occurs when you charge a neutral object by bringing a charged object near it. See Figure 23.9 on page 396.

By Jawad Ahmad

Electric Discharges

Electric discharge happens/occurs when an e- jumps from a negatively charged object to a neutral or positively charged object.

Lightning is produced/created when air currents separate charges inside a storm cloud.

The negative charge in the storm cloud induces a positive charge in another storm cloud or on the ground. When the charge difference is large enough the e- flow by lightning.

Lighting can move from the cloud to the ground, from the ground to the cloud, or from one cloud to another cloud. See Figure 23.10 on page 397.

You can protect your house/property from lightning by installing a lightning rod. In a lightning rod a metal pole is attached to a wire. A lightning rod lets electricity from lighting reach the ground instead of a building or house.

Safety Tip: When you see lightning stay away from high places, open areas, trees, and conductors like metal fences/gates and water. Stay inside a building or hard topped car since the conducting metals can redirect the lightning away from you.

http://ralphott.blogspot.com/2011/06/therapy-metaphors-lightning-rod.html

23.3 Making Electrons Flow

Static discharge is not common enough to give electrical objects the energy they need to be on for long periods of time. The solution is a current.

I = 𝐞𝐥𝐞𝐜𝐭𝐫𝐢𝐜 𝐜𝐮𝐫𝐫𝐞𝐧𝐭 =∆ charge

∆ time=

∆ q

∆ t= [Amperes] = [A]. Current/I is when e- or ions

move through a conductor.

Question: What is the difference between static electricity and electric current/I?

Answer: Static electricity and electric current/I are the same thing but static electricity does not happen/occur often while electric current flows regularly like water.

Creating a Current I

An electric circuit is a closed loop/path of conductors through which current/I can flow/move. If there is a break/gap in the circuit, current/I will not flow/move. See Figure 23.11 on page 398.

𝐕𝐨𝐥𝐭𝐚𝐠𝐞 = potential difference that causes current/I to flow = [Volts] = [V] The voltage of a battery is similar to gravitational potential energy. Voltage is what causes

current/I to flow/move.

By Jawad Ahmad

Don’t Read Power Sources on Page 399 Resistance

e- hit other e- and atoms in a circuit. Some electric energy gets converted to heat and light. See Figure 23.14 on page 400.

𝐑𝐞𝐬𝐢𝐬𝐭𝐚𝐧𝐜𝐞 = tendency of a material to oppose a current = [Ohms] = [Ω] Ωconductor ≪≪ Ωinsulator

Example: It’s easier to run in air than it is to run in water. This means that the resistance of water is much greater than the resistance of air.

The resistance of an object is similar to the f orce of friction between two objects touching each other.

Wires are made from Cu because it has little resistance and does not become hot when a current/I passes through it.

Incandescent light bulbs are made from W (What element is this?) because it has high resistance.

Thinner wires have more resistance than thicker/wider wires since thinner wires have less space for e- to move. See Figure 23.15 on page 400.

Longer wires have more resistance than shorter wires since longer wires have more length for e- to move. See Figure 23.15 on page 400.

For most metals, as the temperature ↑, the resistance ↑.

For C and Si, which are both nonmetals, as temperature ↑, the resistance ↓.

Read about superconductors on page 400. Ohm’s Law

In a circuit, V = IR, where V is the voltage, I is the current, and R is the resistance of the circuit.

Ohm’s Law makes more sense if you solve for I. Now I = V/R. If the voltage V is increased the current I is increased. If the resistance R is increased the current I is decreased.

Direct and Alternating Current

In a direct current circuit e- flow/move in one direction (Example: batteries). e- will flow from the negative terminal/end to the positive terminal/end.

In an alternating current circuit the terminals alternate/switch between positive and negative ends 60 times per second (Example: house). This means that the direction of the I changes over time.

23.5 Electric Power Power

The rate/amount at which an electric current is converted into other forms is called electric power.

Electric Power = Current × Voltage Difference = IV = [Amperes] × [Volts] = [Watts]

Examples: A toaster oven converts an electric current (Current is the movement of charge.) to heat, a fan converts it to motion, a stereo speaker converts it to sound vibrations, a television converts it to light, a light bulb converts it to heat and light, etc. See Figure 23.25 on page 407.

Electric power is usually measured in kW. Remember that 1k=1000.

By Jawad Ahmad

Electric Energy

Electric energy is the amount of power an electric device/object uses over time.

Electric Energy = Electric power × Time = P × t = [kWatts] × hours] = [kW × h]

Your monthly electric bill will charge you for the amount of electricity you use. The amount of electricity you use depends on the amount of time you use a device and the amount of power the device uses.

Electric Safety

Keep electric appliances/devices/objects away from water. Why?

By Jawad Ahmad

Chapter 24 Magnetism 24.1 The Nature of Magnets

Magnets are everywhere. They are in speakers, telephones, televisions, computers, credit cards, refrigerators, etc.

What is Magnetism?

A magnet has a f orce that can attract or repel other magnets and can also attract other substances/objects.

Magnetic Fields

A magnetic field �⃑⃑� is created when an e- moves around the nucleus in an atom in its energy level (Recall/remember that there are seven principal energy levels in an atom.) and also spins (See Figure 24.2 on page 413) like the Earth does around the Sun.

B⃑⃑ lines, or lines of magnetic force (F⃑ magnetic), can be seen with a bar magnet and iron fillings

(See Figure 24.3 on page 414). Place a straight magnetic bar horizontally on a table and sprinkle/place the iron fillings around the magnet. The iron fillings will move because of the

F⃑ magnetic and make a shape. The shape of the iron fillings are the magnetic field lines.

The magnetic f orce is strongest when the B⃑⃑ lines are drawn closer together. The B⃑⃑ of a magnet is largest close to the magnet and decreases as you go farther away from it.

The electric f orce of a charged object is greatest when the E⃑⃑ lines are drawn closer together.

The E⃑⃑ of a charged object is largest close to the charged object and decreses as you go farther away from it.

Magnetic Poles

Every magnet has a north pole and a south pole.

A charged object has a net positive or negative charge. Never both.

B⃑⃑ lines are greatest at the north pole and south pole.

E⃑⃑ lines are greatest when a “test charge” is closest to the charged object.

B⃑⃑ lines always point perpendicular/90° to the magnet.

E⃑⃑ lines always point perpendicular/90° to the surface of the charged object.

B⃑⃑ lines always travel/point from the north pole to the south pole.

E⃑⃑ lines always travel/point from an area with a net positive charge to an area with a net negative charge.

In a magnet a north pole will repel a north pole and a south pole will repel a south pole. A north pole will attract a south pole and “stick” to it (See Figure 24.4 on page 414).

For E⃑⃑ like charges repel and opposite charges attract. A p+ will attract an e- and vice versa. p+ repel p+ and e- repel e-.

Question: What happens if you break/cut a bar magnet in half?

By Jawad Ahmad

http://www.miniphysics.com/2012/03/o-level-magnetic-field-and-magnetic-field-lines.html

From the figure above the B⃑⃑ lines curve toward each other when opposite poles are moved

closer to each other. The B⃑⃑ lines curve away from each other when similar poles are moved closer to each other.

Below are B⃑⃑ lines for a horseshoe/U magnet (See Figure 24.6 on page 415).

http://mail.rdcrd.ab.ca/~smolesky/Physics30/3Electromagnetism/FOV1-00029468/FOV1-00029475/

http://physicistmac2.blogspot.com/

By Jawad Ahmad

Below are B⃑⃑ lines for a disk magnet (See Figure 24.6 on page 415).

http://learn.rollingrobots.com/STEM/Circuits-and-Electricity/Magnets

Question: What happens if you place two magnets next to each other? The solution is at the bottom of page 415.

Magnets and Materials

Question: Why are some materials magnetic and some materials not magnetic?

Answer: In most materials e- spin in both directions (clockwise and anticlockwise) and cancel each other out. In magnets most e- will spin in one specific direction more than the other direction.

Magnetic domains are small volumes of the magnet where north poles line up with north poles and south poles line up with south poles. A non-magnet will contain many random (not organized) magnetic domains in which north poles from one magnetic domain will cancel out with south poles from another magnetic domain (See Figure 24-7 on page 416). IF something can make the magnetic domains line up, the object develops a magnetic field (See Figure 24.10 on page 418).

24.2 Making Magnets Natural Magnets

Magnetite/lodestone is a natural magnet. Some iron Fe in magnetite is Fe+2 and some is Fe+3. e- pass from one Fe ion to another Fe ion which makes an aligned/organized magnetic domain.

Magnetic Induction

Question: How do magnets magnetize other nonmagnetic objects?

Answer: When a magnet touches a nonmagnetic object the magnetic field of the magnet aligns/organizes the magnetic domains. When all of the magnetic domains in the nonmagnetic object line up a magnetic field is created around the object. This process is called magnetic induction.

Temporary and Permanent Magnets

Temporary magnets are magnets made of materials that are easy to magnetize but lose their magnetism easily. The vibrating atoms in the object will bump/hit each other to get the magnetic domains random/unorganized.

Iron Fe, nickel Ni, and cobalt Co are all permanent magnets. They are all more difficult to magnetize but they stay magnetic for a longer time.

Permanent magnets lose their magnetic properties if they are heated or dropped too hard.

By Jawad Ahmad

24.3 Earth as a Magnet

The Earth is a giant spherical magnet. See Figure 24.12 on page 420. Magnetic Planet

The Earth is tilted/shifted about 11° from its poles.

Scientists assume the inner core of Earth is solid iron and nickel that is spinning/rotating much faster than the outer core of liquid iron.

Changes in Earth’s Magnetic Field

The magnetic fields of Earth changes over time. See Figure 24.13 on page 421.

The polarity of Earth also changes over time. This means that the magnetic North Pole becomes the magnetic South Pole and that the magnetic South Pole becomes the magnetic North Pole.

There is a difference between a geographic North Pole and a magnetic North Pole!!!!

Most reversals are estimated to take between 1,000 and 10,000 years. The latest one, the Brunhes–Matuyama reversal, occurred 780,000 years ago. http://en.wikipedia.org/wiki/Geomagnetic_reversal

The Compass

A compass is an object with a magnetized needle. That means the needle is a small bar magnet that has a north pole and a south pole. See Figure 24.14 on page 422.

If the compass is not next to a magnet then the needle will line up with the magnetic poles of the Earth. The needle pointing north will point to the magnetic South Pole and the needle pointing south will point to the magnetic north pole.

If the compass is next to a magnet then the needle will line up with the magnetic field of the magnet.

The Magnetosphere

The magnetosphere deflects/repels particles from the sun that are dangerous to living creatures. See Figure 24.16 on page 423.

Some particles are attracted to the poles of the Earth. They crash into the Earth near the magnetic north pole and the magnetic South Pole. When these particles go through the atmosphere of the Earth a green and purple light is seen. This so called an aurora (or northern lights or southern lights).

Jim Raines, FIPS operations engineer (University of Michigan) added, “We’re trying to understand how the sun, the grand-daddy of all that is life, interacts with the planets. It is Earth’s magnetosphere that keeps our atmosphere from being stripped away. And that makes it vital to the existence of life on our planet.” http://www.universetoday.com/89322/extreme-solar-wind-blasts-mercurys-poles/

http://www.universetoday.com/89322/extreme-solar-wind-blasts-mercurys-poles/

By Jawad Ahmad

Chapter 25 Electromagnetism 25.1 Magnetism from Electricity Moving Charges and Magnetic Fields

Charged objects at rest (like an electron or a proton) give out an electric field E⃑⃑ . The E⃑⃑ of an object always points from a positively charged object to a negatively charged object. This is from chapter 23.

Charged objects that are vibrating give out both an electric field E⃑⃑ and a magnetic field B⃑⃑ . This is from chapter 21.

A moving charge (or current 𝐈 =∆𝐪

∆𝐭) develops/produces a magnetic field �⃑⃑� . The B⃑⃑ of a

straight wire is given by the equation B⃑⃑ =μ0I

2πr, where B⃑⃑ is the magnetic field from the

current in a wire at a point outside the wire, μ0 is a constant, I is the current in the wire, and r is the distance from the wire. Understand that as the current increases the magnetic field at a point also increases (directly proportional). As the distance from the wire increases, the magnetic field at that point will decrease (inversely proportional). You don’t need to memorize the above equation, only the relationships.

You can use the “right hand rule” to find the direction of the B⃑⃑ of the wire. Point your thumb in the direction of the current and grab/hold the wire. The direction in which your

fingers move around the wire is the direction of the B⃑⃑ (See Figure 25.1 on page 427).

http://www.explorelearning.com/index.cfm?method=cresource.dspexpguide&resourceid=611

By Jawad Ahmad

Solenoids and Electromagnets Solenoids

A solenoid is a wire bent into many loops. The magnetic field inside a solenoid is much larger than the magnetic field outside a straight wire.

The magnetic field inside a solenoid is B⃑⃑ = μ0nI, where B⃑⃑ is the magnetic field inside a solenoid, μ0 is a constant, n is the number of loops per length, and I is the current of the

wire. The B⃑⃑ inside a solenoid increases as the number of loops per unit length n increases and/or if the current I in the wire increases. You don’t need to memorize the above equation, only the relationships.

You can use the “right hand rule” to find the direction of the magnetic field lines in a solenoid. Point/wrap your fingers in the direction of the current in the wire. The direction of your thumb is the direction of the arrows of the magnetic field and the north pole.

Question: How can we Δ the direction of the north and south pole of the solenoid?

http://www.alpcentauri.info/solenoids_and_electromagnets.html

Electromagnets

An object in which a wire is looped around it becomes an electromagnet. When there is a I

in the wire the B⃑⃑ inside an electromagnet is much larger than the B⃑⃑ inside a solenoid. See Figure 25.3 on page 428.

When there is a I in the wire a B⃑⃑ magnetizes the nail and increases the B⃑⃑ inside the solenoid. Electromagnets are only magnetic when a I flows. When there is no I the nail is not magnetized.

http://learn.uci.edu/oo/getOCWPage.php?course=OC0811004&lesson=007&topic=010&page=10

Using Electromagnets

Electromagnets are easy to control.

We can change the north pole and south pole of an electromagnet by reversing the I in the wire.

We can increase the B⃑⃑ of the electromagnet by increasing the I in the wire.

Electromagnets can be used to make objects move.

By Jawad Ahmad

Electric Doorbell

When you press/ring a doorbell button a closed circuit/loop is made. An electromagnet pulls a hammer towards it. The hammer hits the bell and a spring pulls the hammer back to its original position. This repeats itself until the button is not pressed. See Figure 25.4 on page 429.

Galvanometers

An electromagnet is placed in between a fixed (not moving) north and south pole. When a current I goes through the electromagnet the electromagnet magnetizes and rotates until it lines up with the fixed magnets.

A galvanometer is used to measure I. Galvanometers are also used to show us the amount of fuel in a car. See Figure 25.6 on page 430.

Don’t Read Electric Motors on Pages 431-432 25.2 Electricity from Magnetism

From section 25.1 we learned that a moving charge q (or current I =∆q

∆t) creates a magnetic

field B⃑⃑ (A current I in a wire, solenoid, and electromagnet all produce a magnetic field B⃑⃑ ).

Question: Is the opposite true? Can magnetic fields create an electric current?

Answer: Yes. A changing magnetic field �⃑⃑� will produce a current 𝐈 in a circuit.

Moving a magnet through a solenoid produces an electric current I. Because of this electricity is now inexpensive and readily available.

Producing Electricity

How do we do this? Take a long wire and make it into a circuit. Attach the circuit to an ammeter (An ammeter measures the current in a wire). Make one small loop in the wire so it looks like a solenoid. Place a magnet under the loop and move the magnet up and down through the solenoid. Moving the magnet through the solenoid produces a current I. You can see the magnitude (or number) of the current I by looking at the ammeter.

The current I in the circuit (or wire) is directly proportional to the number of loops in the solenoid and the speed of the magnet through the solenoid.

It doesn’t matter if the wire is stationary (doesn’t move) and the magnet moves or if the magnet is stationary and the wire moves because motion is relative. To have a current I in the circuit (or wire) the magnet has to go through the solenoid. It doesn’t matter if the magnet is moving or not (See “Relative Motion” on section 12.1).

By Jawad Ahmad

Electromagnetic Induction

A changing magnetic field �⃑⃑� through the solenoid will produce a current 𝐈 in the circuit (or

wire). The generation/creation of a I by a CHANGING B⃑⃑ is called electromagnetic induction.

The I produced in the circuit (or wire) by electromagnetic induction comes from the F⃑ external

of the B⃑⃑ .

By looking at Figure 25.9 on page 434, a wire moves down between two fixed/permanent

(not moving) magnets. The magnets give the wire an F⃑ external and the electrons in the wire

move perpendicular (90°) from the direction of the B⃑⃑ . Electric Generators

A motor will convert electric energy to kinetic/mechanical energy.

A generator will convert kinetic/mechanical energy to electric energy by electromagnetic induction.

An example of converting mechanical energy to electric energy is shown in Figure 25.10 on page 434. A mechanical force turns a shaft which is attached to a wire (or coil) that is

between two fixed/permanent (not moving) magnets. There is a magnetic field B⃑⃑ between

the magnets. The magnetic field B⃑⃑ will create a current I in the moving circuit (or wire). The energy produced by this system is directly proportional to the size of the wire (or coil) and the speed of the wire (or coil). In this figure mechanical energy is converted to electrical energy.

Types of Current 𝐈

Alternating 𝐈: The generator in Figure 25.10 on page 434 produces an alternating current I since the current I in the wire (or loop) is changing direction every time the wire (or loop) turns. For more info go here: http://www.allaboutcircuits.com/vol_2/chpt_1/1.html

Direct 𝐈: The current I in chemical batteries from automobiles and flashlights do not alternate. The current I moves (or flows) in one direction. Generators can be designed/made to produce direct current.

Uses of Generators

Car generators, called alternators, are powered by belts. Electricity produced by the generator recharges the battery and powers other devices/appliances/machines in the car. The energy that would have been wasted is converted into electricity. The energy stored in the battery can be later used to power the cars electric motor.

Most of the electricity in the world is produced by generators. See Figure 25.11 on page 435.

Changing Voltage

Voltage is a measure of the energy carried by the electric charges in a current. The electricity from power plants can be as great as 750,000 volts but most of the everyday devices you use will have no more than a few volts. A transformer changes the voltage of an alternating current.

Question: What does a transformer look like?

By Jawad Ahmad

http://tfwiki.net/wiki/Optimus_Prime_%28G1%29

http://www.indiamart.com/ng-electronics-mumbai/current-transformers.html

How a Transformer Works

A transformer is made of an iron core with two wires (or coils). One wire coil is the primary coil and the other wire coil is the secondary coil. An alternating current I is in the primary

coil. The alternating current I produces a changing magnetic field B⃑⃑ in the iron core. This

changing magnetic field B⃑⃑ in the iron core will induce an alternating current I in the secondary coil. See Figure 25.12 on page 436.

The current I in the primary coil must be an AC. A DC will not give a change in B⃑⃑ . Only a

change in B⃑⃑ will give electromagnetic induction and create a current I in the secondary coil.

By Jawad Ahmad

http://en.wikipedia.org/wiki/File:Transformer3d_col3.svg

Step-Up and Step-Down Transformers

If the number of primary coils is greater than the number of secondary coils then you have a step-down transformer. This will decrease the voltage in the wire. See Figure 25.13 on page 436.

If the number of primary coils is less than the number of secondary coils then you have a step-up transformer. This will increase the voltage in the wire.

Vsecondary

Vprimary=

nsecondary

nprimary

Transmitting Electricity

Question: Why is the voltage in a wire so high?

Answer: The amount of heat generated/produced in a wire is directly proportional to the current I in the wire. The high heat (or large current I) in a wire leads to lost energy and lost efficiency (bad). It’s better to have low current in a wire. Current I in a wire is decreased by increasing the voltage. By increasing the voltage both current I and power that is wasted is reduced (or made less). High voltage power lines are very efficient at transferring alternating current electricity.

Transformers are very efficient because they change voltages with very little energy loss. Because of this power plants can be placed far away from your house. See Figure 25-14 on page 437.

There is a Lot of Vocabulary. Read the Summaries on Pages 424 and

438.

By Jawad Ahmad

Equations for Major 2 and the Final

average speed =∑distance traveled

∑ time= [m/s]

Page 196

v⃑ elocity =Δ d⃑ isplacement

Δ time=

x⃑ final − x⃑ initial

∆ time= [m/s]

a⃑ cceleration =∆v⃑

∆t=

v⃑ final − v⃑ initial

∆t= [m/s2]

Page 200

m⃑⃑⃑ omentum = p⃑ = mass × v⃑ elocity = mv⃑ = [kg × m/s]

Page 202

Conservation of M⃑⃑⃑ omentum

p⃑ initial = p⃑ final

Page 203

F⃑ gravity =Gm1m2

r2= [Newtons]

Page 213

F⃑ gravity = W⃑⃑⃑ eight = m × g⃑ = [Newtons]

Page 214

Newton’s Second Law of Motion

∑F⃑ ext = m × a⃑ = m ×∆v⃑

∆t= [Newtons]

Page 218

Newton’s Third Law of Motion

F⃑ 1 on 2 = −F⃑ 2 on 1

m1a⃑ 1 = m2a⃑ 2

Page 219

work = F⃑ orce × d⃑ isplacement × cos θ = ∆Energy= Efinal − Einitial

= (KEfinal + GPEfinal) − (KEinitial

+ GPEinitial) = [Joules]

Page 241

By Jawad Ahmad

Power =work

time=

F⃑ orce × d⃑ isplacement × cosθ

time= F⃑ orce × v⃑ elocity × cos θ = [Watts]

Page 242

kinetic energy = KE =1

2mv⃑ 2 = [Joules]

Page 263

gravitational potential energy = GPE = mg⃑ y⃑ = [Joules]

Page 264

Law of Conservation of Energy

Energyinitial = Energyfinal

Page 269

mechanical energy = KE + GPE =1

2mv⃑ 2 + mg⃑ y⃑

Page 269

λ = wavelength = length of a wave = [meters]

Page 323

f = frequency =# cycles

second= [

1

sec] = [Hertz]

Page 323

T = period =1

f= time to complete one cycle

= [seconds]

Page 324

wavespeed = wavelength × frequency = λ × f = [m/s]

Page 325

Intensity =Energy

Area= [

Joules

m2 ]

Page 339

F⃑ electric =kq1q2

r2= [Newtons]

Coulomb’s Law

Electric f orce between two objects Page 393

By Jawad Ahmad

V = IR

V = Voltage = [Volts]

I = Current = [Amperes] R = Resistance = [Ohms]

Ohm’s Law Page 400

Electric Power = Current × Voltage Difference

= I × V = [Amperes × Volts]= [Watts]

Electric power is the rate at which an electric current is converted into other forms. Page 406

Electric Energy = Electric power × Time

= P × t = [Watts] × hours]= [W × h]

Electric energy is the amount of power an electric device/object uses over time. Page 408

B⃑⃑ =μ0I

2πr

B⃑⃑ = Magnetic field outside a I carrying wire μ0 = constant

I = Current in the wire r = distance from the wire

Magnetic field outside a current carrying wire Page 427

B⃑⃑ = μ0nI

B⃑⃑ = Magnetic field inside a I carrying solenoid μ0 = constant

n = # loops/length I = Current in the wire

Magnetic field inside a current carrying solenoid Page 428

Vsecondary

Vprimary=

nsecondary

nprimary

Vprimary = Voltage in the primary coil

Vsecondary = Voltage in the secondary coil

nprimary = # of loops in the primary coil

nsecondary = # of loops in the secondary coil

Page 436