General Physics (PHY 2130)
Introduction
•  Syllabus and teaching strategy
•  Physics
•  Introduction
•  Mathematical review
http://www.physics.wayne.edu/~apetrov/PHY2130/
Chapter 1
Syllabus and teaching strategy
Lecturer:
, Room 358 Physics Building,
Phone: 313-577-2739, or 313-577-2720 (for messages)
e-mail: apetrov@physics.wayne.edu,
Web: http://www.physics.wayne.edu/~apetrov/
Office Hours:
MWF 10:40-11:35 AM, at 2009 SCI
MW 3:00-4:00 PM, on main campus, Physics Building, Room 358
or
.
Grading:
3 in-class exams (100 pts each)
Quizzes (5 out of 7 quizzes)/attendance
Final Exam
Online Homework (WebAssign)
BONUS: Planetarium visit
300 pts
60 pts
200 pts
40 pts
3 pts
LABORATORY
PHY 2131 is the laboratory portion of PHY 2130.
►
►

It is a co-requisite

Laboratory is treated as a separate part of the course
Your laboratory Manual will be available on Blackboard
►
For further details: Dr. Scott Payson at
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Lab sections of PHY 2131 begin in week of January 10
313-577-3280
3
QUIZ SECTIONS
►
Quiz sections meet once per week and are important.
  Allow you to meet together in small groups.
  Practice problems.
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Quiz instructors will work a few examples.
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You will be given 7 quizzes (5 best + attendance is reported to me)
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Five best quizzes plus attendance will be counted toward your final
quiz score: Total possible = 60 pts [50 (quizzes) + 10 (attendance)].
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►
No individual make-up quizzes will be given
Math proficiency test: first quiz section! Make sure you attend.
4
EXAMS
►
There will be three regular, so-called “hour” exams (typically 50-55
minutes allowed) given during the term.
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Each exam consists of Multiple Choice questions (no partial credit).
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Your lowest score of the three may be replaced by one-half of the
final exam score, if doing so improves your grade.
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There will be NO make-up exams.
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If you miss an hour exam for any reason, that score of 0 will be your
low score.
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You MUST bring your Wayne State ID to the exam and present it to
a proctor when you hand in the exam.
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No electronic devices (other than a standalone calculator) are
allowed in the room during the exam (no iPods, headphones, cellphones, Blackberries, etc.)
5
ONLINE HOMEWORK
►
The WebAssign online testing system (http://webassign.net)
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40 points of the 600 point total for the course.
►
If you purchase the textbook at the bookstore, it will include a
WebAssign access card valid for two semesters. ( Or purchase it
through the internet)
►
Details can be found in the Syllabus.
►
Consult the WebAssign Student Guide for additional information.
6
TIPS FOR SURVIVING SUCCEEDING IN INTRODUCTORY
PHYSICS
►
Purchase the text. Make use
of the many helpful aspects of
the text.
►
Actually read the text (use a
highlighter, if you prefer).
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Put in the time. At least 2
hours outside of the class for
every hour of lecture.
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Practice, practice, practice.
►
Strive for understanding.
Come to the class.
7
ADDITIONAL STUDY HELP
►  Physics
Resource Center,
in room 172 Physics (the
center will open a couple
of weeks after the term
begins).
►  Your
professor and quiz
instructor
8
NOTE: If you need a certain letter grade in this class to get
into/stay in a program, please keep track of your grade
throughout the semester to make sure that you are WELL
above the required level.
9
Introduction
10
Why Study Physics?
  Physics is the foundation of every science (astronomy, biology, chemistry).
WSU: diverse set of problems, ranging from understanding the origins of the
universe, to probing subatomic interactions, to studying the behavior of
magnetic domains in hard drives, to characterizing single molecule
diffusion.
  Many pieces of technology and/or medical equipment and procedures are
developed with the help of physicists.
  Studying physics will help you develop good thinking skills, problem
solving skills, and give you the background needed to differentiate
between science and pseudoscience.
11
Scientific Notation
Is there a shorthand way of writing very large and/or very small numbers?
Prof. Sakamoto’s lab:
Studies of myosin (one of motor proteins)
Size of the object: 10 nm = 0.000000001 m
Prof. Cackett’s lab:
Studies of X-ray binaries (star systems with
one normal star and a black hole)
Size of the object: 130 000 km = 130 000 000 m
12
Example: The radius of the sun is 700,000 km.
Write as 7.0×105 km.
When properly written this number will be
between 1.0 and 10.0
Example: The radius of a hydrogen atom is 0.0000000000529 m. This is more
easily written as 5.29×10-11 m.
13
Physics Speak
Be aware that physicists have their own precise definitions of some words that
are different from their common English language definitions.
Examples: speed and velocity are no longer synonyms;
mass and weight are no longer synonyms;
acceleration is a change of speed or direction, etc.
14
Math
Galileo Wrote:
Philosophy is written in this grand book, the universe, which stands
continually open to our gaze. But the book cannot be understood unless
one first learns to comprehend the language and read the characters in
which it is written. It is written in the language of mathematics, and its
characters are triangles, circles, and other geometric figures without
which it is humanly impossible to understand a single word of it; without
these, one is wandering in a dark labyrinth.
From Opere Il Saggiatore p. 171 by Galileo Galilei (http://www-gap.dcs.stand.ac.uk/~history/Mathematicians/Galileo.html)
Basically, the language spoken by physicists is mathematics.
15
This:
Means this:
y = mx + b
x is multiplied by the factor m.
The terms mx and b are added together.
16
Example:
x
y = +c
a
x is multiplied by the factor 1/a or x is divided by the factor a. The terms x/a
and c are added together.
17
Calculating percentages
►  How
would you calculate by how much a quantity
changed if you are given by how many percent it
increased/decreased?
The general rule is to multiply the quantity by
n ⎞
⎛
⎜1 ±
⎟
⎝ 100 ⎠
where the (+) is used if the quantity is increasing and (–) is used if the
quantity is decreasing by n percent.
18
Example: You put $10,000 in a CD for one year. The APY is 3.05%.
How much interest does the bank pay you at the end of the year?
$10,000 ×1.0305 = $10,305
! 3.05% $
#1+
&
" 100% %
The bank pays you $305 in interest.
19
Example: You have $5,000 invested in stock XYZ. It loses 6.4% of its
value today. How much is your investment now worth?
$5,000 × 0.936 = $4,680
20
Proportions
A∝ B
1
A∝
B
A is proportional to B. The value of A is directly
dependent on the value of B.
A is proportional to 1/B. The value of A is inversely
dependent on the value of B.
21
Example: For items at the grocery store:
cost ∝ weight
The more you buy, the more you pay. This is just the relationship between
cost and weight.
To change from ∝ to = we need to know the proportionality constant.
cost = (cost per pound) × (weight)
22
Example
A large ice cube is 30 in on each side. If the
length of each side is increased by a factor of
two, the surface area
A)
B)
C)
D)
increases by a factor of ½.
increases by a factor of 2.
increases by a factor of 4.
increases by a factor of 8.
A large ice cube is 30 in on each side. If the length of
each side is increased by a factor of two, the surface
area…
Notations: let’s call the length of the “old” side as
aold and the “new” length as anew.
Given:
anew = 2 aold
Find:
Anew/Aold=?
Solution:
Recall that each cube has six faces. The area of each
face is Aface = a2, so the total surface area is A = 6 a2.
Thus,
2
new
2
old
Anew 6a
=
Aold 6a
=
(
6 2aold
2
6aold
)
2
2
4aold
= 2 =4
aold
Note: we did not use the fact that aold=30 in!
Example
A large ice cube is 30 in on each side. If the
length of each side is increased by a factor of
two, the surface area
A)
B)
C)
D)
increases by a factor of ½.
increases by a factor of 2.
increases by a factor of 4.
increases by a factor of 8.
Measurements
► Basis
of testing theories in science
► Need to have consistent systems of units for
the measurements
► Uncertainties are inherent
► Need rules for dealing with the uncertainties
Systems of Measurement
► Standardized
systems
  agreed upon by some authority, usually a
governmental body
► SI
-- Systéme International
  agreed to in 1960 by an international committee
  main system used in this course
  also called mks for the first letters in the units
of the fundamental quantities
Systems of Measurements
► cgs
-- Gaussian system
  named for the first letters of the units it uses for
fundamental quantities
► US
Customary
  everyday units (ft, etc.)
  often uses weight, in pounds, instead of mass
as a fundamental quantity
Basic Quantities and Their Dimension
► Length
[L]
► Mass [M]
► Time [T]
Why do we need standards?
Length
► Units
  SI -- meter, m
  cgs -- centimeter, cm
  US Customary -- foot, ft
► Defined
in terms of a meter -- the distance
traveled by light in a vacuum during a given
time (1/299 792 458 s)
Mass
► Units
  SI -- kilogram, kg
  cgs -- gram, g
  USC -- slug, slug
► Defined
in terms of kilogram, based on a
specific Pt-Ir cylinder kept at the
International Bureau of Standards
Standard Kilogram
Why is it hidden under two glass domes?
Time
► Units
  seconds, s in all three systems
► Defined
in terms of the oscillation of
radiation from a cesium atom
(9 192 631 700 times frequency of light emitted)
Time Measurements
US “Official” Atomic Clock