Dimensional Analysis
Can often use dimensions to check validity of a formula (L:
length, M: mass, T: time)
Example 1: can 4r2 be the volume of a sphere?
Volume = cubic meters or L3, (area = L2)
But has dimensions of L2, so no, is not volume
Example 2: ca
1
Wayne State University
Department of Physics and Astronomy
PHY 2171 General Physics
Experiment # 8
SIMPLE HARMONIC MOTION
1.
Synopsis
You will observe and understand the simplest form of periodic motion-simple harmonic motion.
2.
Objectiv
PHY 2130
Class 1, 8/27/14
Sections 001 & 004 (David Bowen)
Pick up Syllabus at desk in front
Back-channel URL: http:/todaysmeet/Frameworks
Syllabus
Pick up a copy of the Syllabus in front
Review (Syllabus is assigned reading):
LL Sections start today
Lab
Types of forces:
Weight W = mg down: force of gravity
Tension T along rope, know dir only, mag from N2
Normal (^ shared surface) N, know dir only, mag from N2
Friction (/ shared surface) fs, know dir only, mag from N2
General Method (Framework)
Start fro
Why study Physics?
Most reliable knowledge humans can access
o
Tells you the result beforehand correctly!
Learn about chain of causality, being quantitative where
possible, value of causal theory (applies to diagnosis)
Success here predicts success in Me
Position, Displacement, Distance
Example: A bug walks 10 cm to the right along a windowsill
then turns and walks 5 cm to the left and stops
What is bugs displacement from start to finish?
What distance did the bug travel, start to finish?
x axis to right
Blocks, Pulley and Ramp
m2 hangs free of ramp, m1 has
coefficient of kinetic friction mk
m1, y: +N m1gcos = 0
N = m1gcos and fk = mkN
m1, x: +T fk Wy = m1a
or T - mkm1gcosq - m1gsin = m1a
m2, x: -T + m2g = m2a
T = m1(a + g(mkcosq + sin) = m2(g a)
a = g(m
Chapter 3
Vectors
This subject is absolutely critical
Motion in 2D: Vectors
Define a new type of thing a vector, has both magnitude (+ve
value, units) and direction
Algebraic symbol: bold with arrow above
Graphical symbol: arrow
Can be moved / without ch
Contact Forces
Contact forces: shared surface
Normal force N is ^
Example of book on table, Ftable on book = W = mg up, Fbook on table =
W down
m = 8 kgm W = 8 9.8
= 78.4 N
/ Component of Contact Force
/ Component is friction. Two types:
If surface is sl
Blocks, Pulley and Ramp
m2 hangs free of ramp, m1 has
coefficient of kinetic friction mk
m1, y: +N m1gcos = 0
N = m1gcos and fk = mkN
m1, x: +T fk Wy = m1a
or T - mkm1gcosq - m1gsin = m1a
m2, x: -T + m2g = m2a
T = m1(a + g(mkcosq + sin) = m2(g a)
a = g(m
Wayne State University
Department of Physics and Astronomy
PHY 2131 General Physics
Experiment # 7
MOMENT OF INERTIA AND ANGULAR
MOMENTUM
1.
Synopsis
You will measure the moments of inertia of two different objects (Part I) a