Transcript Review Session

Review Session
“What we done?”
Baron von Frankenstein
For Wednesday’s Exam
Pencil
 Calculator (Cheap is fine)
 Be ON TIME
 Know your PID and bring ID card with
you.

•Background
Material
CHAPTER 1.5
NOTE DOCUMENT ON
SITE THAT CONTAINS THE
MUSIC RELATED
MATERIAL THAT WE HAVE
COVERED TO DATE
IT ALSO CONTAINS MATERIAL THAT WE
HAVE NOT COVERED
Question
Is anyone having problems downloading
lecture set 5?
Send an email with PC and OS information.
Basic Topics

Background Material on Scientific Method
◦ Mostly reading
◦ Bode’s Law
 Not important but is an example of someone
whose results were invalidated by later
observations.
 This concept of testing and retesting a “Law” or
Theory and modifying to include both new and
older information is the foundation of modern
physical science
WHAT ARE SOME
EXAMPLES OF
LAWS/THEORIES THAT
ARE CURRENTLY
ACCEPTED AS GOOD
MODELS
How about Murphy’s Law??
If it can go wrong, it will.
The toast will always fall buttered side down.
Can you do “scientific
notation”?
30  10 2
?
100
30,000,000  ?
16  10
?
4
4  10
8
16  10
?
9
4  10
8
Etc.
Boltzman
WHAT DID HE DO?
WHY WAS IT
IMPORTANT?
Remember this (see site)?
1.2
"airspeed" - relative
1
ope
n
0.8
0.6
0.4
0.2
0
-0.2
0
2
4
6
8
Time in milli-seconds
T=~2ms=0.002 seconds
close
10
d
12
Period = T=~2ms=0.002 seconds
If it takes 0.002 seconds to to complete something,
how many times can it do it in one second?
1
1
Answer  " frequency" 

0.002 sec 2 10 3
1
 103  500 sec 1  500 Hertz
2
1
f
T
Don’t forget
Milli = 1/1000
 Millimeter = 1/1000 meter = 0.001 meter
 Milli-second = 1/1000 sec = 0.001 seconds

1 Kg = ?
1 M Hz =
Standards
Why do we need them
 What are they

◦ Time
◦ Distance
◦ Mass
Dynamics
Concept of equilibrium
 Velocity

◦ Change in “distance” /time

Acceleration
◦ Change in velocity (speed?)/time
Concept of average speed and velocity
 Concept of average speed and velocity
 Concept of average acceleration
 The nature of VECTORS


A runner leaves home for a training
session. He typically runs at a speed of 8
miles per hour. It takes him two hours to
make the trip.
◦
◦
◦
◦
◦
What was his average speed?
What was his average velocity?
What was his average acceleration?
How far did he run?
What color underwear was he wearing?
Acceleration of Gravity
What is g?
 I throw an object up with a speed of 30
m/s,

◦ how long does it take to get to the point
where it stops?
◦ How much longer does it take to be falling at
a speed of 15 m/s

Do it a step at a time.
A woman throws a 50kg vertically with an
initial speed of 20 m/s. How far does it
travel to the point where it is at rest?
The initial velocity is v0 20 m/s
 The final velocity is zero
 The acceleration is –g

◦ (MINUS .. Against the original throw.)
It travels for 2 seconds
 Let’s look at the graph

velocity
Graph (m/s vs. sec) – Example
uniform acceleration: v=at
Area=(1/2 base x height)
Area = distance traveled
Area=(1/2)vt=(1/2)at x t
Area=dist=(1/2)af2
v+Dv
v



Area=v Dt
=Dx

time
You plan to drive 60 miles with the cruise control set
at 50 mph. How long will it take to get there?
Newton’s Laws

Newton 1
◦ A body at rest or moving at a constant
velocity will tend to remain at rest or at the
same constant velocity unless acted upon by
an external force.

Newton II
◦ A body subjected to an unbalanced force (F)
will accelerate (a) at a rate that is
proportional to the unbalanced force.
◦ The relationship DEFINES the concept of
mass or inertia
Newton’s Laws
1
a  F  kF    F
m
F  ma
Frank is holding 10 pounds of
groceries. He weighs 300 pounds.
How large is the normal force?
?
?
Question
When the same net force is applied to object A and object B, object
A has an acceleration three times that of object B. Which of the following is
correct?
a. Object A has three times the mass of object B.
b. Object A has one-third the mass of object B.
c. Object A has a different, less streamlined shape than object B.
d. Object A has more friction than object B.
A ball with a weight of 20 N is thrown vertically upward. What are
the size and direction of the force on the ball just as it reaches the top
of its path?
a. zero
b. 10 N upward
c. 10 N downward
d. 20 N downward
A ball falling from a great height will reach
terminal speed when its _____ goes to zero.
a. inertia
b. net force
c. weight
d. speed
A crate has a mass of 24 kg. What
applied force is required to produce an
acceleration of 3 m/s2 if the frictional
force is known to be 90 N?
a. 72 N
b. 90 N
c. 162 N
d. 240 N
A ball with a weight of 20 N is thrown vertically
upward. What is the acceleration of the ball just
as it reaches the top of its path?
a. zero
b. 10 m/s2 downward
c. 10 m/s2 upward
d. The acceleration cannot be determined.
A ball with a weight of 20 N is thrown
vertically upward. What are the size and
direction of the force on the ball just as it
reaches the top of its path?
a. zero
b. 10 N upward
c. 10 N downward
d. 20 N downward