1 PHY 113 C General Physics I 11 AM 1215 P M MWF Olin 101 Plan for Lecture 26 Comments on preparing for Final Exam Comprehensive review Part II Course assessment 12052013 PHY 113 C Fall 2013 Lecture 26 ID: 658079
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12/05/2013
PHY 113 C Fall 2013 -- Lecture 26
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PHY 113 C General Physics I
11 AM – 12:15
P
M MWF Olin 101
Plan for Lecture 26:
Comments on preparing for Final Exam
Comprehensive review – Part II
Course
assessmentSlide2
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Final exam schedule for PHY 113 CSlide4
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Comments on Final Exam
It will be comprehensive (covering material from Chapters 1-22)
It is scheduled for 9 AM Dec. 12
th
in Olin 101
In class format
only
; no time pressure
May bring
4
equation sheets
Format will be similar to previous exams; may see problems similar to those on previous exams Slide5
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General advice on how to prepare for Final Exam
Review fundamental concepts and their corresponding equations
Develop equation sheets that help you solve example problems on all of the material. (You can assume that empirical constants and parameters will be given to you; they need not take up space on your equation sheet.)
Practice problem solving techniques.
If you find mysteries, unanswered questions, etc., please contact me.Slide6
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Problem solving steps
Visualize problem – labeling variables
Determine which basic physical principle(s) apply
Write down the appropriate equations using the variables defined in step 1.
Check whether you have the correct amount of information to solve the problem (same number of knowns and unknowns).
Solve the equations.
Check whether your answer makes sense (units, order of magnitude, etc.).Slide7
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Review of some basic concepts
Vectors
Keep track of 2 or more components (or magnitude and direction)
Examples
Position vector
Velocity
Acceleration
Force
Momentum
Scalars
Single (signed) quantity
Examples
Time
Energy
Kinetic energy
Work
Potential energy
Pressure
Temperature
Mass
Density
VolumeSlide8
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Review of some basic concepts
Newton’s second lawSlide9
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Review of some basic concepts
Newton’s second law for angular motionSlide10
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Review of energy concepts:Slide11
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Summary of work, potential energy, kinetic energy relationshipsSlide12
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Extension of concepts of energy conservation to extended objectsSlide13
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CM
CMSlide14
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Three round balls, each having a mass M and radius R, start from rest at the top of the incline. After they are released, they roll without slipping down the incline. Which ball will reach the bottom first?
A
B
CSlide15
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iclicker
exercise:
In previous example which of the equations on your equation sheet would be most useful?Slide16
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From your questions -- (question from Exam 2) Slide17
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Comment on circular motion -- uniform circular motionSlide18
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r
In terms of time period
T
for one cycle:
In terms of the frequency
f
of complete cycles:
Comment on circular motion -- uniform circular motionSlide19
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Comment on circular motion -- uniform circular motion – effects on gravitationally attractive bodiesSlide20
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Comment on circular motion -- non-uniform circular motion
r
At each instant of time
Note that if speed
v
is
not
constant, then there will
also
be a tangential component of acceleration:
a
c
a
qSlide21
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From your questions -- (question from Exam 1)
Neglecting any possible
dissipative
forces acting on this system, determine the magnitude of the velocity of the ball
v
f
as it is caught by the person at the coordinates (
x
f
,y
f
).
What
is the angle
q
f
?
Determine
the net work of gravity on the ball at it moves from the initial to final positions in its trajectory: .Slide22
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From your questions -- (question from Exam 1)
Neglecting any possible
dissipative
forces acting on this system, determine the magnitude of the velocity of the ball
v
f
as it is caught by the person at the coordinates (
x
f
,y
f
).
What
is the angle
q
f
?
Determine
the net work of gravity on the ball at it moves from the initial to final positions in its trajectory: .Slide23
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From your questions -- force diagrams
m
q
1
q
2
F
1
F
2
mgSlide24
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mg(-
j
)
r
T
q
F
=m
a
T- mg
cos
q = 0
-
mg sin
q = -
ma
q
t
=I
a
r mg sin
q
= mr
2
a =
mra
q
From your questions -- pendulumSlide25
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From your questions --
driven Harmonic oscillatorSlide26
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From your questions --
driven Harmonic oscillatorSlide27
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Similar problem from
webassign
:
Damping is negligible for a 0.165-kg object hanging from a light, 6.30-N/m spring. A sinusoidal force with an amplitude of 1.70 N drives the system. At what frequency will the force make the object vibrate with an amplitude of 0.600m?
(usually neglected)Slide28
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Examples of two-dimensional collision;
balls
moving on a frictionless surfaceSlide29
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Examples of two-dimensional collision;
balls
moving on a frictionless
surface – energy conservation?
Note: In these collision analyses, we are neglecting forces and potential energy
iclicker
question
Why?
We are cheating physics
We are applying the laws of physics correctlySlide30
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Examples of two-dimensional collision;
balls
moving on a frictionless
surface – energy conservation?
Assuming that we applying the laws of physics correctly – we can ask the question – Is (kinetic) energy conserved?Slide31
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From your questions -- conservation
of angular momentum
m
m
d
1
d
1
m
m
d
2
d
2
I
1
=2md
1
2
I
2
=2md
2
2
I
1
w
1
=I
2
w
2
w
2
=
w
1
I
1
/I
2
w
1
w
2Slide32
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Example form
Webassign
#11
X
t
1
t
3
t
2
iclicker
exercise
When the pivot point is O, which torque is zero?
A.
t
1
?
B.
t
2
?
C.
t
3
?Slide33
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An
example of the application of torque on a rigid object:
A horizontal 800 N merry-go-round is a solid disc of radius 1.50 m and is started from rest by a constant horizontal force of 50 N applied tangentially to the cylinder. Find the kinetic energy of solid cylinder after 3 s.
K = ½ I
w
2
t = I a w =
w
i
+ a
t =
a
t
In this case I = ½ m R
2
and
t
= FR
R
FSlide34
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Webassign
questions on fluids (Assignment #17)
A hypodermic syringe contains a medicine with the density of water (see figure below). The barrel of the syringe has a cross-sectional area
A
= 2.40 10
-5
m
2
, and the needle has a cross-sectional area
a
= 1.00 10
-8
m
2
. In the absence of a force on the plunger, the pressure everywhere is 1.00 atm. A force of magnitude 2.65 N acts on the plunger, making medicine squirt horizontally from the needle. Determine the speed of the medicine as it leaves the needle's tip.
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Send email or come to see me if you have further questions.
THANKS!