PHYSICS 231
INTRODUCTORY PHYSICS I
www.pa.msu.edu/courses/phy231
Scott Pratt
prattsc@msu.edu
(517) 355-9200, ext. 2016
Office Hours:
T-R, immediately after class in 4208A BPS
Tuesday: 1:00-2:30 PM in 1248 BPS
Homework
•Graded electronically with LON-CAPA
http://msu.loncapa.org
• Due Wednesdays at 10:00 AM
• No HW due week after Exam 1 and Exam 3
Strosacker Center, 1248 BPS Bldg.
• Monday 9:00 AM - noon, 12:30-6:00 PM
• Tuesday 8:30 AM - 6:00 PM
• Wednesday 8:30 AM - 10:00 AM
EXAMS
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4 Midterms (on Thursdays during class time)
1 Final
11 questions one each midterm, graded on scale of 10
Drop lowest of 4 midterms, no make-ups
22 questions on final, graded on scale of 20
Exams are closed book - closed note
Midterms will have HIGH overlap with homework
Midterms 2, 3 and 4 will include problem from previous
midterm
• Final will be made of reworded Midterm problems
GRADES
4 Midterms
60%
•Feb. 5, Mar. 4, Apr. 1, Apr. 29
•During class in 1410 BPS (right here)
•Lowest score dropped
•No makeups
•11 questions, graded on scale of 10
•Questions largely from homework
Final Exam
30%
•May 4, 5:45-7:45 PM, location TBA
•22 questions, graded on scale of 20
•Reworded Midterm problems
Homework
10%
•LON-CAPA, www.loncapa.org
•Log-in with pilot ID & password
Textbook
• Serway and Faughn
• Old editions are fine
Succeeding in Physics 231
• Do your homework!
• Use the help room (1248 BPS) !
Stay away from ALLMSU
• Make sure you understand both “why” and “why not”
• Interrupt the lecturer
General Physics
• First Semester (Phy 231)
• Mechanics
• Thermodynamics
• Simple harmonic motion
• Waves
Second Semester (Phy 232)
• Electromagnetism
• Relativity
• Modern Physics
• (Quantum Mechanics, …, etc.)
Mechanics
• Half the course
• Quantified largely by Galileo
• Problems involve:
velocity, acceleration, mass, momentum, energy,
torque, angular momentum, moment of inertia…
UNITS (Systéme Internationale)
Dimension
SI (mks) Unit
Definition
Length
meters (m)
Distance traveled by light in
1/(299,792,458) s
Mass
kilogram (kg)
Mass of a specific platinumiridium allow cylinder kept by
Intl. Bureau of Weights and
Measures at Sèvres, France
Time
seconds (s)
9,192,631,700 oscillations of
cesium atom
Standard Kilogram
at Sèvres
Dimensional Analysis
Dimensions & units can be treated algebraically.
Variable from Eq.
x
m
t
v=(xf-xi)/t
a=(vf-vi)/t
dimension
L
M
T
L/T
L/T2
Dimensional Analysis
Checking equations with dimensional analysis:
1 2
x f  xi  vi t  at
2
(L/T2)T2=L
L
(L/T)T=L
• Each term must have same dimension
• Two variables can not be added if dimensions
are different
• Multiplying variables is always fine
• Numbers (e.g. 1/2 or p) are dimensionless
Example 1.1
Check the equation for dimensional consistency:
2
mc
2
mgh 

mc
2
1  (v / c )
Here, m is a mass, g is an acceleration,
c is a velocity, h is a length
Example 1.2
Consider the equation:
2
v
Mm
m G 2
r
r
Where m and M are masses, r is a radius and
v is a velocity.
What are the dimensions of G ?
L3/(MT2)
Units vs. Dimensions
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Dimensions: L, T, M, L/T …
Units: m, mm, cm, kg, g, mg, s, hr, years …
When equation is all algebra: check dimensions
When numbers are inserted: check units
Units obey same rules as dimensions:
Never add terms with different units
• Angles are dimensionless but have units
(degrees or radians)
• In physics sin(Y) or cos(Y) never occur unless Y
is dimensionless
Example 1.3
Grandma traveled 27 minutes at 44 m/s.
How many miles did Grandma travel?
44.3 miles
Prefixes
In addition to mks units,
standard prefixes can be used,
e.g., cm, mm, mm, nm