Chapter 13 Energy & Power

How is energy important to us?

1

Energy

The ability to do work or cause change is called energy.

Works is the transfer of energy.

Two types of energy: Kinetic energy is

energy of motion. Potential energy is

energy of position or shape.

2

Forms of Energy

Mechanical energy Chemical energy Nuclear energy Electrical energy Electromagnetic

energy Thermal energy Acoustical energy

3

Which form of energy is sound?

4

acous

tical

chemica

l

elec

trica

l

therm

al

0 000

A. acoustical

B. chemical

C. electrical

D. thermal

10SecondsRemaining

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Forms of Energy

Mechanical energy is the energy associated with the motion or position of an object.

Thermal energy is the total energy of the particles in an object.

Chemical energy is the potential energy stored in chemical bonds that hold chemical compounds together.

5

Forms of Energy

Electrical energy is moving electric charges produce electricity and energy.

Electromagnetic energy travels in waves and have both electrical & magnetic properties.

Nuclear energy is energy stored in the nucleus of an atom and is released during nuclear reactions.

6

Forms of Energy

Accoustical energy is energy of sound.

7

What type of energy is produced from a battery?

Chemica

l energ.

..

Elec

trica

l Ene..

.

Mech

anical E

ne...

Solar E

nergy

I nee

d help. ...

0% 0% 0%0%0%

A. Chemical energy

B. Electrical Energy

C. Mechanical Energy

D. Solar Energy

E. I need help. I don’t understand.

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What energy is required to operate this device?

0% 0% 0%0%0%

A. Electrical energy

B. Chemical Energy

C. Mechanical Energy

D. Thermal Energy

E. Help!

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What is the type present in the sun?

Electr

ical

Kinetic

Chemical

Nucle

ar

I don’t

know. ..

.

0 0 000

A. Electrical

B. Kinetic

C. Chemical

D. Nuclear

E. I don’t know. I need help.

10

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What type of energy is dependent on the height of an object?

Chemical p

oten...

Elasti

c potent..

.

Grav

itational ..

.

Kinetic

I don’t

know. ..

.

0 0 000

A. Chemical potential

B. Elastic potential

C. Gravitational potential

D. Kinetic

E. I don’t know. I need help.

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Kinetic Energy

Remember, kinetic energy is energy of motion.

KE=½(mass x velocity2) Doubling the mass,

doubles the kinetic energy.

Double the velocity, quadruple the kinetic energy.

12

Potential Energy

Elastic potential energy is energy stored when an object is stretched or compressed.

Gravitational potential energy is energy stored because of the height of the object’s position.

Chemical potential energy is energy stored in the bonds between atoms.

GPE= weight x height. Energy is measured in

units called Joules.

13

At what point(s) does the swinging pendulum have the most kinetic energy?

A B C D H

elp!

0 0 000

A. A

B. B

C. C

D. D

E. Help!

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At what point(s) would the swinging pendulum have the most potential energy?

A B C D H

elp!

0 0 000

A. A

B. B

C. C

D. D

E. Help!

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What is the relationship between potential and kinetic energy?

Ther

e is

no re

latio

nship

.

As

PE incr

ease

s, K

E ...

As

PE incr

ease

s, K

E ...

As

PE dec

reas

es, K

E...

0 000

A. There is no relationship.

B. As PE increases, KE increases.

C. As PE increases, KE decreases.

D. As PE decreases, KE decreases.

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Which of the following devices transforms electrical energy into acoustic energy?

Ele

ctric

Guita

r

Rad

io

I-Pod

All

of the

above

None

of the

abo

ve

0 0 000

A. Electric Guitar

B. Radio

C. I-Pod

D. All of the above

E. None of the above

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Joe Shmoe turns on a flashlight. Which of the following lists the energy transformations in the system?

0 000

A. Electrical chemical mechanical radiant

B. Chemical electrical thermal mechanical

C. Nuclear chemical electrical

D. Mechanical chemical Electrical radiant

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In which units do we measure energy?

gra

m jo

ule

kilo

gram

New

ton

0 000

1. gram

2. joule

3. kilogram

4. Newton

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When you wind up a rubber band on an airplane, what type of energy does this represent?

Chem

ical

pot

entia

l ...

Ela

stic

pote

ntial e

nergy

Gra

vita

tional

pote

nti..

Kin

etic

ener

gy

0 000

1. Chemical potential energy

2. Elastic potential energy

3. Gravitational potential energy

4. Kinetic energy

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Which type of energy is illustrated by a ball rolling down a hallway?

Chem

ical

pot

entia

l e...

Ela

stic

pote

ntial e

nergy

Gra

vita

tional

pote

nti..

Kin

etic

ener

gy

0 000

1. Chemical potential energy

2. Elastic potential energy

3. Gravitational potential energy

4. Kinetic energy

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Energy Conversion and Conservation

A change from one form of energy to another is called energy conversion.

Most forms of energy can be converted into any other form.

What is the energy conversion of the flashlight in the diagram on the right?

22

Energy Conversion

What is the energy conversion for the fan in the diagram on the right?

23

Conservation of Energy

Law of conservation of energy states that when one form of energy is converted to another, no energy is destroyed in the process.

According to the law of conservation of energy, energy cannot be created or destroyed.

24

Fossil Fuels

Fossil fuels are formed from the burying of plants and animals.

Include coal, petroleum and natural gas.

Fossil fuels contain energy that came from the sun.

Fossil fuels can be burned to release the potential chemical energy stored millions of years ago.

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Work

Work is exerting a force on an object, causing it to move.

W = F x d Work is measured

in joules.

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Power

Power is the rate at which work is done or the amount of work done in a unit of time.

Power is calculated by dividing the amount of work done by the amount of time taken to do work. Power = work/time Power = force x

distance/time Power is

measured in watts.

27

What happens to the energy as a pendulum is started at its highest dropping point?

Kin

etic

chan

ges to

p...

Pote

ntial c

hange

s to

...

Pote

ntial e

quals

kine

tic.

Ther

e is

no c

hange

...

0 000

1. Kinetic changes to potential.

2. Potential changes to kinetic.

3. Potential equals kinetic.

4. There is no change between kinetic and potential.

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What is the proper energy conversion that take place when turning on a flashlight?

Chem

ical

to e

lect

rical

...

Ele

ctric

al to

chem

ical

...

Ther

mal

to e

lect

rical

..

Ther

mal

to c

hemic

al ..

0 000

1. Chemical to electrical to thermal.

2. Electrical to chemical to thermal.

3. Thermal to electrical to chemical.

4. Thermal to chemical to electrical.

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Which of the following types of energy is not a fossil fuel?

Coal

.

Hyd

roel

ectri

c.

Nat

ural g

as.

Pet

role

um.

0 000

1. Coal.

2. Hydroelectric.

3. Natural gas.

4. Petroleum.

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Pendulum Lab

Purpose: The purpose of this lab is for the students to learn which factor affects the period of the swing of a pendulum.

Materials: 3 different weights meter stick string stopwatch ring stand

31

Pendulum Lab

Procedure:

1. Tie a weight to the end of a string.

2. Attached the other end of the string to the ring stand.

3. Pull the weight back a standard distance and release the weight.

4. Time how long it takes for ten cycles of the pendulum. Enter this data on the data table.

32

Pendulum Lab

5. Divide the time by ten to find the time for a single swing.

6. Change the weight and repeat procedures 1-5.

7. Change the weight and repeat procedures 1-5.

8. Next change the length of the string and keep the weight the same. Repeat procedures 1-5.

33

Pendulum Lab

9. Change the length of the string a second time and keep the weight the same. Repeat procedures 1-5.

10. Change the angle of release. Repeat procedures 1-5.

11. Change the angle of release. Repeat procedures 1-5.

34

Pendulum Lab

Questions:1. Make a drawing of the pendulum. Indicate on

the diagram the positions of the maximum potential energy and the maximum kinetic energy.

2. What were the variables in this experiment? Which was the manipulative variable and which was the responding variable?

3. Explain how the Law of the Conservation of Energy is observed in this experiment.

4. What forces act on the pendulum to stop its motion?

35

Pendulum Lab

Look at the diagram on the right.

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Formative Assessment Review What are the two types of energy? (kinetic and potential) Which type of energy is energy of motion? (kinetic) Which type of energy is stored energy? (potential) Which type of energy is stored in a stretched

rubberband or compressed spring? (elastic potential energy) Which type of energy is stored because of the position

of the object? (gravitational potential energy)

37

Formative Assessment Review What is the formula for calculating kinetic energy? (KE=mv2/2) What is the formula for calculating gravitational

potential energy? (GPE=w x h or GPE=m x g x h) Name seven forms of energy. (mechanical, thermal, chemical, electrical,

electromagnetic, nuclear, acoustic) Which law states that energy is neither created or

destroyed? (Law of Conservation of Energy) What is the formula for calculating Power? (P=w/t)

38

Formative Assessment Review What unit is power measured? (watt) What unit is work or energy measured? (joule) What do we call the ability to do work or cause change? (energy) What happens to kinetic energy if the mass is doubled? (doubles) What happens to kinetic energy if the velocity doubles? (quadruples) _______________ is the transfer of energy. (work)

39

Formative Assessment Review What is the numerical value of gravitational

acceleration? (9.8 m/s2) What energy is associated with motion or position? (mechanical) What energy is associated with the total energy of the

particles of an object? (thermal) What energy is associated with the potential energy

stored in chemical bonds? (chemical) What energy is produced by moving electric charges? (electrical)

40

Formative Assessment Review What energy travels in waves? (electromagnetic) What energy is stored in the nucleus of an atom? (nuclear) What is it called when an energy form changes to

another form of energy? (converstions) Who stated that energy can be created by destroying

matter? (Einstein) How is energy released from fossil fuel? (burning)

41

Formative Assessment Review What energy is mechanical energy converted to by

friction? (thermal) Name three fossil fuels. (coal, petroleum, natural gas) _______________ is the rate at which work is done. (power) How many watts are in one horsepower? (746)

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