For students enrolled in an
introductory physics lab,
PHYS 2108 and PHYS 2109
lab classes begin this week
(August 20 - 24). You must
attend the first week
of class or send an email to
[email protected] PRIOR
TO CLASS explaining your
absence or you will be
dropped from the course. Welcome, Physics Majors!
Freshman physics major? (or thinking about
becoming one?
Are you a physics minor or double major?
If so, You are invited to join us for free
pizza!. We will meet:
Friday August 24, 4:30-6:00 pm
Nicholson Hall, Room 435
We will give you some important information, like ..
Ray Chastain • Who are the important people to know?
• How you can do research in physics and astronomy?
• Who are The Society of Physics Students?
Rongying Jin (professor)
Department of Physics & Astronomy
Office: 229B Nicholson Hall
Email: [email protected]
Tel: (225) 578-0028
Visit my personal website for more information:
http://www.phys.lsu.edu/rongying/
You are Science & Engineering Majors.
You are registered for PHYS 2101.
You want to learn PHYS 2101 ??
You want to have good grade !!
Fall 2012: PHYS2101 Section 6
Reading Assignments: Lecture schedule is provided - read material before lecture!
Lectures:
Concepts will be developed through the lectures, demonstrations and class discussion
Homework:
Best way to learn the material: -- Quizzes & Exams mostly based on
HW
Class Information is also via WebAssign
WebAssign will handle most of your class-related needs: homework,
formulae sheets, practice tests
http://webassign.net/student.html
IMPORTANT: Try to log into WebAssign TODAY
✪  Click “I have a class key” then input your class key: lsu
3573 6541.
✪  If you have used WebAssign before, your old password will be in effect
✪  If you have NOT used WebAssign before, you can logon in by using your LSU
PAWS email address without the @lsu.edu, and setup your own password.
✪  If you have a problem in logon, please check:
(1) username (has to be PAWS username);
(2) if you have paid for accessing WebAssign;
(3) if you are in my class roster. Please contact me if you cannot logon.
The first homework assignment is posted.
HW will be due in 1 week ! Start early !!
Course details -- see syllabus
Class Format - Announcements
- Mixture of Power Point and Chalk Board/Overhead
- Some theory …. Some problems… - Power Point slides are available on class website & my own website - Please ask questions (and correct me!).
Course:
•  It is assumed that everyone has credit in PHYS 1100 so the material in Chapters 1-6 (vectors,
1- and 2-D kinematics, Newton’s laws) will only be reviewed in the first two weeks of class. If
you tested out of PHYS 1100, you will be assumed to know this material and should review it
carefully if you don't remember it well. You will be tested on this material in the third week of
class. •  After the first two weeks the course assumes a more normal pace and will cover most of the
section contained in chapters 7 – 20, with the exception of chapter 17, which will be skipped. •  The core material of the course covers concepts in mechanics, fluids, wave motion, and
thermodynamics. The lecture schedule will specifically indicate sections of text that are
covered on a given week. Students should read and become familiar with this material before
coming to class.
•  Course grades will be determined by quizzes (mostly in weekly base), Homework, four 1-hour
mid-term tests, and a final (see following).
Course details -- see syllabus
Homework:
•  Homework assignments will be posted online at: http://webassign.net/student.html
(details announced in class). They are similar to text book HW.
•  Except when noted in class, due dates for homework assignments will generally be
midnight on Monday after the assignment. •  Full solutions will be available at webassign after the due date.
Quiz:
• There will be a quiz (10-15 min.) based primarily on the HW problems due that week. Tutoring:
•  If you do not understand the material or you experience difficulty in working the
problems, seek help from the graduate tutors in Room 102 of Nicholson Hall. This
service is free.
•  There will be 2101 Supplemental, which is also free. More information coming soon.
•  Make sure you take advantage of the instructor office hours posted. You should feel free
to go to any instructor's office hours if you have class conflicts with your own
instructor's office hours; all sections follow the same schedule and use the same
homework assignments.
Course details -- see syllabus
Exams:
• There will be four 1-hour mid term exams.
• There will be no make-up exams: if you need to miss an exam for a university-scheduled
function, make sure you obtain permission from your instructor in advance. If you miss an
exam with permission your other scores will be adjusted.
• Exams will contain a combination of multiple-choice questions and work problems for which
you must show your work.
• The scheduled dates for exams are as following:
Exam 1
Exam 2
Exam 3
Final 100 points
100 points
100 points
200 points
September 18, 2012
October 16, 2012
November 13, 2012
December 6, 2012
6 – 7 pm
6 – 7 pm
6 – 7 pm
3 – 5 pm
Lockett 10
Lockett 10
Lockett 10
TBA
Students having three or more final examinations in a 24 hour period may request permission
to take no more than two examinations on the day concerned. These requests must be requested
by the student and approved by the instructor before Friday Nov. 9th.
• A formula sheet will also be provided and no other material is to be used during the exam. You
will need a scientific calculator; graphic calculators are fine, but not necessary.
• Old exams (with solutions) are posted here, but notice that the number of exams and material
covered in them is different in different years.
Course details -- see syllabus
Grading:
•  HW-50 pts. –The two lowest will be dropped. The quizzes and many of the exam
questions are taken from the Home Work. •  Quiz - 50 pts. The quiz grade will be computed from the average grade.
•  Middle Exams - 100 pts. each: Total 300 pts.
•  The final exam will be composed of two parts, an examination of Ch. 18-20 (100 pts)
and a separated cumulative part (100 pts).
• Your final grade will be based on 600 total points. The demarcations in % of 600 pts are
given below
• A >88%, B> 77%, C>60%, D>50%
• If your percentage grade is within these ranges, you are guaranteed the associated letter
grade. At the end of the course the instructors may adjust these cut offs slightly but only
downwards.
Basic concepts:
1. Measurement of a physical parameter
2. Units, systems of units (example: SI)
3. Basic units in mechanics
4. Changing units
5. Significant figures
SI Base Units – seven
1)  meter (m)
distance
2)  kilogram (kg) mass
3)  second (s)
time
4)  ampere (A) electric current
5)  kelvin (K)
temperature
6)  mole (mol) amount of stuff
7)  candela (cd) intensity of light prefix
Derived Unit
hertz (Hz)
newton (N)
pascal (Pa)
joule (J)
Measures
frequency
force
pressure
energy
or work
Derivation
/s
kg·(m/s2)
N/m2
N·m
Formal Def.
s-1
kg·m·s-2
kg·m-1·s-2
kg·m2·s-2
Symbol Factor
Giga
G
109
Mega
M
106
Kilo
k
103
Centi
c
10–2
Milli
m
10–3
Micro
µ
10–6
Nano
n
10–9
See Appendix A: International System of Units
See Appendix D: Conversion Factors
Significant figures…
“Units” example
Alpha Centauri is the closest “star”. It is 4.3 light-years away.
How many kilometers away is the star from earth ?
Write down: What do you know? What are we trying to get to?
4.3 light years = time it takes for light to travel distance
Distance = speed × time
What’s the speed (rate)?
Speed of light = 3 ×108 m/s
Now do it..
 3.15 × 10 7 s   3 × 10 8 m   1 km 
distance = ( 4.3 years ) 
  1000 m 
s
 1 year  
time
= 40 × 1012 km or 40 petameters (Pm)
speed
Questions
When we measure physical quantities, the units may be anything that is
reasonable as long as they are well defined. It’s usually best to use the
international standard units. Density may be defined as the mass of an object
divided by its volume. Which of the following units would probably not be
acceptable units of density?
a) gallons/liter
b) kilograms/m3
c) pounds/ft3
d) slugs/yd3
e) grams/milliliter
Questions
A certain physical quantity, R, is calculated using the formula: R = 4a2(b – c)
where a is a speed (a distance traveled per unit time interval) and b and c are
distances. What is the SI unit for R?
a) cm/h
b) cm2/s
c) m2/h
d) m2/s
e) m3/s2
Questions
Given that one inch is equal to 25.4 mm. How many meters equal 11.3 ft?
a) 3.45 m
b) 4.42 m
c) 2.95 m
d) 1.30 m
e) 2.21 m
Solution:
in=25.4mm
ft=12in=12x2.54mm=304.8mm=0.305m
Questions
Which one of the following pairs of units may not be added
together, even after the appropriate unit conversions
have been made?
a) feet and centimeters
b) seconds and slugs
c) meters and miles
d) grams and kilograms
e) hours and years
Be sure that numerical answers appear
with appropriate SI units. Points will be
deducted for missing, incorrect, or
“silly” units.
If the final answer is in fact a
dimentionless quantity, please write the
numerical result followed by the word
“dimensionless”
Basic Concepts:
(SI Unit: m)
Displacement:
Average velocity:
(SI Unit: m/s)
Instantaneous velocity:
Average acceleration:
(SI Unit: m/s2)
Instantaneous acceleration
We are dealing with Kinematics
Example
Average Velocity: The World’s Fastest Jet-Engine Car
Andy Green in the car ThrustSSC set a world record of 341.1 m/s in 1997. To
establish such a record, the driver makes two runs through the course, one in
each direction, to nullify wind effects. From the data, determine the average
velocity for each run.
Δx x − x o
v ave = v =
=
Δt
t − to

Δx +1609 m

v1st =
=
= +339.5 m s
Δt
4.740 s
€

Δx −1609 m

v 2nd =
=
= −342.7 m s
Δt
4.695 s
m/s
Entire trip: Average speed? 341.1
Average velocity? Can Displacement be larger than Distance? When is it equal? 0 m/s
Δx=0 !
Special Case: Motion with Constant Acceleration
Motion with Constant Acceleration
The x(t) versus t plot is a parabola that intercepts
the vertical axis at x = x0.
The v(t) versus t plot is a straight line with
slope = a and intercept = v0.
The acceleration a is a constant.
Example
The brakes on your car are capable of creating a constant deceleration of 5.2 m/s2. a) If you are going 137 km/hr and suddenly see a state trooper, what is the minimum time in which you can get your car under the 90 km/hr speed limit?
b) How far has your car traveled during the deceleration?
Special Case: free-falling body motion
Close to the surface of the Earth all objects move toward the center of the Earth
with an acceleration whose magnitude is constant and equal to 9.8 m/s2. We use
the symbol g to indicate the acceleration of an object in free fall. a
B
y
A
Question
A person standing at the edge of a cliff throws one
ball straight up and another ball straight down at
the same initial speed. Neglecting air resistance,
the ball to hit the ground below the cliff with the
greater speed is the one initially thrown
1. 
2. 
3. 
upward.
downward.
neither—they both hit at the
same speed.
Kinematics: Taking Advantage of Symmetry