physics 218: mechanics

Physics 218: Mechanics Instructor: Dr. Tatiana Erukhimova

Sections 807, 808, 809

Lecture 1

Howdy!Dr. Tatiana Erukhimova

[year]

Atmospheric Thermodynamics

Elementary Physics and Chemistry

Gerald R. North

Tatiana L. Erukhimova

Texas A & M University

Fall 2008: SLATE award Fall 2009: SLATE awardRecipient of 2009 Distinguished Achievement College-Level Award in Teaching

Overview of Today’s Class

•Folders

•Syllabus and Course requirements

•Tricks to survive

•Why study Physics?

(we’ll do some demos today)

Please take the folders

Section 807 (recitation at 8 am) – red folders

Section 808 (recitation at 10:20 am) – yellow folders

Section 809 (recitation at 13:40 pm) – green folders

If you forgot your Section number, please check it with me

We’ll use the folders only in class:

Please pick them up before each class and return back after the class

DO NOT take them home!

I’ll return the tests and quizzes in these folders

Syllabus

Instructor Dr. Tatiana Erukhimova

Homepage http://faculty.physics.tamu.edu/etanya/P218/

Office: 308 Mitchell Physics bldg

Phone: 845-5644 E-mail: etanya@tamu.edu

Class times: TR: 2:20 pm to 3:35 pm Sections 807-809

Location: 204 MPHY

Office hours:TWR 1 pm – 2pm or by appointment

Textbook: “Don’t Panic: Volume I”, by William H. Bassichis, 5th Edition

No lab manual is required

Dedicated

students like it!

Clickers

We will use CPS clickers for various kinds of assessment: pop quizzes, homework quizzes, in class discussion, etc. You will need to buy the clickers at the MSC Bookstore and register them for this class at http://elearning.tamu.edu

Grade Policy

Exams 45% Lab 5%

Quizzes (including homework quizzes) 10% Final 40%

•You must pass both the lecture (3 midterm exams, final exam, homework) and laboratory (>70%) parts of the course separately in order to pass the course

Grade Policy (cont)

•If your grade on the Final Exam is higher than your lowest grade on one of the three exams during the semester, the grade on the Final will replace that one lowest exam grade in computing the course grade (it will only replace one grade in case of two exams having the same lowest grade). •The Final Exam grade cannot be used to replace an exam that has been missed without an University excused absence. The missed exam will count as a zero when computing your final grade.

Grade Policy (cont)

All Exams are

•Closed book

•No numbers! In general the problems will be formula solutions with variables

•Problems will be similar to those on homework and recitation

Similar does not mean identical!

Many of you have taken high school physics are used to being given formulas and numbers to plug into them…

We are not going to do this on the exams! We’ll use variables…

Good news: If you do the homework the way we ask you to, you’ll be well prepared for the exams!

HomeworkYou’ll have weekly homework assignments

Every week you’ll have hw quiz (for 10-15 min) with one problem from your assignment.

Good news: you are allowed to use YOUR notes (no books or photocopies)

Bad news: small partial credit (for hw). You have to show your work, get a correct formula, and, if required, a numerical answer

Check my webpage for hw assignments

Example for Week 1 (Week Aug 31):

Week Aug 31 (due Sep 7): All Chapter 1 problems and exercises

“Due” means that I’ll give you a hw quiz on that day

Exam schedule

All mid-term exams will be from 7:00 to 9:30 pm

September  28             Exam I October      26             Exam II

November  23             Exam III

Final             TBA

I make help sessions before each midterm exam and the final. Also, there will be week-in-review sessions

However, these sessions cannot substitute for regular class attendance.  They are to give you a good guidance on how to prepare for the test and to succeed in problem solving.

Please check my webpage for help sessions schedule

Standards

We’re teaching you how to THINK about how to solve technical problems. – If you think this class is “plug and chug”

you’re going to be VERY unhappy– If you think you can memorize a few formulas

and ace this course, you are very mistaken

My Advise to You• Be proactive!! Get into it and have fun• Be serious about an old rule of thumb: you have to

study 2-3 hours a week outside the class per each credit hour

• Don’t miss classes (lectures, recitations, labs)• Solve all problems and exercises after each Chapter

in the book• Don’t fall into the “I understand the concepts but I

can’t do the problems” trap. It means you haven’t done enough of the problems in the chapters.

• Every year we have lots of students who really think they understand but fail during the exams. Don’t let this happen to you!

Why study physics?

• the most fundamental of the sciences provides the basis of our understanding of the Universe;

We do want to find out how things work!

• scientists of all disciplines make use of the ideas of physics

• fun to learn and adventure!

What is the role of 218 in your career?

P218 foundation

Do your best to build a good foundation for your engineering career!

Language of physics is math

First week we will learn some calculus: derivatives and integrals that we’ll need in this course

Studies show that you need to be good at math to solve physics problems

(This is a skill! Anyone can learn it, you just have to learn to deal with the fear and learn it anyways).

TRACK A

# Passed Calc I %

407 179 44

468 387 82

Some statistics…

What happens when physics is ignored?

On January 28, 1986, seven astronauts were killed when the space shuttle they were piloting, the Challenger, exploded just over a minute into the flight. The failure of the solid rocket booster O-rings to seal properly at low temperature allowed hot combustion gases to leak from the side of the booster and burn through the external fuel tank.

O-ring

What happens when physics is ignored?

Cooling polymers: transition from rubbery to glass state

At low temperature molecular bonds become strongerMolecules move too slow to respond to bendingRubber becomes brittle

Let’s do some experiments at

low temperature!

Water Nitrogen Oxygen

Boils

Freezes

100 C (212 F) -196 C (-322 F) -183 C (-297 F)

0 C (32 F) -210 C (-346 F) -223 C (-369 F)

Our air is ¾ Nitrogen and ¼ Oxygen

How cold is it?

Vostok station -89 C

Triton, the moon of Neptune:-235 C (38 K)

Nitrogen boils: -196 C (77 K)

We are lucky that here on Earth air is gaseous, while water is liquid!

Why is there smoke?This is water vapor! Cold N2 leads to condensation of water droplets in the air.

Why this vapor goes down while water vapor from boiling water goes up?

This is how the clouds are formed!

Because this vapor is cold!

Cooling living cells

Rubber regains elasticity when it thaws

Living cells are permanently damaged by freezing

Mechanics

• Various forms of motion:

- mechanical

- electromagnetic

- thermal, etc.

Mechanical form of motion is connected with displacements of various bodies relative to each other and with changes of the shapes of the bodies

Historical Notes

• History of mechanics linked with history of human culture

• Aristotle (384-322 B.C.); Physics

• Archimedes (3rd century B.C.), the law of lever, the law of equilibrium for floating bodies

• Galileo Galilei (1564-1624), the basic law of motion

Archimedes (3rd century B.C.), the law of lever, the law of equilibrium for floating bodies

GIVE ME A PLACE TO STAND AND I WILL MOVE THE EARTH

Antikythera Mechanism decoded?!

• Found in 1901 near the Antikythera island in a Roman shipwreck dated 80 BC• Remained a puzzle for over 100 years • Recently deciphered using X-ray tomography, optical imaging, texture mapping

Nature, 30 November 2006 (page 587)

A sophisticated mechanical computer

Predicts:• Lunar and solar cycles, taking into account ellipticity of the moon’s orbit• Lunar and solar eclipses• Accurate positions of the sun, moon, and planets• Luni-solar calendar

Unfortunately, the secret of making such devices was lost after the invasion of Romans.Next time when much simpler mechanisms of this kind appeared was in Islamic countries in 1300 AD (Al Biruni)Later they were imported to Europe and became clock mechanisms

a

v

a = g = const for all bodies independently on their masses

Galileo Galilei (1564-1624), the basic law of motion

A New Era of Science

Newton’s law of gravitation

Clockwork universe

1905 Albert Einstein

"Gravitation cannot be held responsible for people falling in love.“ Albert Einstein

Some typical lengths in the Universe

a) The most distant galaxies are about 1026 m, or 1023 km, away.

b) The sun is 1.5 x 1011 m, or 150 000 000 km from the Earth.

c) The diameter of the Earth is 1.28 x 107 m, or 12,800 km.

d) A typical human is about 1.7 m, or 170 cm, tall.

Hubble Deep Field

Farthest and oldest objects are 12-13 billion light years, or 1026 m away!

1011 galaxies in the observable universe

1 Astronomical Unit = 1.51011 m

107 m

Earth radius = 6378.164 km

Some typical lengths in the Universe

e) Human red blood cells are about 8 x 10-6 m (0.008 mm, or 8 m) in diameter.

f) Atoms about 10-10 m, or 10-4 m, in radius.

g) Typical atomic nuclei have radii of about 10-14

m, or 10-5 nm.

Have a great day!

Please return the foldersReading: Chapter 1