Transcript Physics 218: Mechanics Lecture 1 Instructor: Dr. Tatiana Erukhimova Sections 807, 808, 809

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 award
Recipient 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: [email protected]
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
Dedicated
students like it!
No lab manual is required
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%
Grade Policy (cont)
•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.
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!
Homework
You’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
October 26
November 23
Final
Exam I
Exam II
Exam III
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?
Do your best to build a good foundation
for your engineering career!
P218 foundation
Language of physics is math
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).
First week we will learn some calculus:
derivatives and integrals that we’ll need in this
course
Some statistics…
TRACK A
#
Passed Calc I
%
407
179
44
468
387
82
What happens when physics is ignored?
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
Cooling polymers: transition from rubbery to glass state
At low temperature molecular bonds become stronger
Molecules move too slow to respond to bending
Rubber becomes brittle
Let’s do some experiments at
low temperature!
Water
Nitrogen
Boils
100 C (212 F)
-196 C (-322 F)
-183 C (-297 F)
Freezes
0 C (32 F)
-210 C (-346 F)
-223 C (-369 F)
Oxygen
Our air is ¾ Nitrogen and ¼ Oxygen
How cold is it?
Vostok station -89 C
Nitrogen boils: -196 C (77 K)
Triton, the moon of Neptune:
-235 C (38 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.
This is how the clouds are formed!
Why this vapor goes down while water vapor from
boiling water goes up?
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
Galileo Galilei (1564-1624),
the basic law of motion
a
a = g = const
v
for all bodies independently on their
masses
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
1011 galaxies in the
observable universe
Farthest and oldest
objects are 12-13 billion
light years, or 1026 m
away!
1 Astronomical Unit = 1.51011 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 mm) in
diameter.
f) Atoms about 10-10 m, or
10-4 mm, in radius.
g) Typical atomic nuclei
have radii of about 10-14
m, or 10-5 nm.
Have a great day!
Please return the folders
Reading: Chapter 1