Download Clicker Question

Announcements
• CAPA Assignment #12 due this Friday at 10 pm
• Section: Lab #5, Springs and Things (note no prelab)
• Nagle’s office hours 2-3 pm cancelled
• Exam #3 on Tuesday, November 8th at 7:30 pm
• Today is a review of some exam topics….
Tomorrow evening at 7:30 PM:
• Bring a #2 pencil, an eraser, and a calculator.
• No outside materials
• No cell phones or smart phones as calculator
• Same room assignments as previous exams
Reminder of Materials Available
• Textbook and example problems in the text
• Professor Dubson’s Chapter Notes (see link on web page)
• Clicker questions as posted in lecture notes
• CAPA problems, solutions on CULearn
• Practice exam and solutions on CULearn
• Lab manuals and problems
PE = work done
to move into
current
configuration
v 2
 
 2 f
r T
rpm
f 
60
kinematical
equations
   0   t

ki 1

2
   0   t   t
2

 2   02  2
v2
ar 
 r 2
r
centripetal acceleration
Clicker Question
Room Frequency BA
A projectile is fired straight up and then comes back
down to the ground. There is a force of air resistance.
During the entire flight, the total work done by the force
of gravity is:
A) Zero
B) Positive
C) Negative
During the entire flight, the total work done by the force
of air resistance is:
A) Zero
B) Positive
C) Negative
Clicker Question
Room Frequency BA
A pendulum is launched in two different
ways. During both launches, the bob is
given an initial speed 3 m/s and the same
initial angle from vertical.
Which launch will cause the pendulum to
swing the largest angle from the
equilibrium position to the left side?
A) Launch 1
B) Launch 2
C) Both are the same.
Clicker Question
Room Frequency BA
A block of mass m with initial speed v slides up a
frictionless ramp of height h inclined at angle  as
shown. Assume no friction.
Whether the block makes it to the top depend on the
angle . What do you think about this statement?
A) True
B) False
Clicker Question
Room Frequency BA
A block of mass m slides down a rough ramp of height h. Its initial
speed is zero. Its final speed at the bottom of the ramp is v.
m
h
Which is the amount of thermal energy, Ethermal, released from
the block’s motion down the ramp?
1
A) mgh  mv 2
2
1
C) mv 2  mgh
2
E) mgh
1
B) mgh  mv 2
2
1
D) mv 2
2
KEi  PEi  Eithermal  KE f  PE f  E thermal
f
1 2
0  mgh  0  mv  0  Ethermal
2
1 2
Ethermal  mgh  mv
2
Clicker Question
Room Frequency BA
A pendulum consists of a mass m at the end of a string of
length L. When the string is vertical, the mass has speed
v0.
What is the maximum height h to which the mass swings?
Clicker Question
Room Frequency BA
Ball 1 of mass m moving right with speed v bounces off
ball 2 with mass M (M > m) and then moves left with
speed 2v.
What is the magnitude of the impulse of Ball #1
A) mv
B) 2mv C) 3mv D) ½ mv E) 0
Clicker Question
Room Frequency BA
A bullet of mass m traveling with initial speed v hits a
block of mass M on a frictionless table. The bullet
buries itself in the block, and the two together have a
final velocity vf.
The total kinetic energy of the bullet+block after the
collisions is _______ the total KE before the collision.
A) Greater than
B) Less than
C) Equal to
Clicker Question
Room Frequency BA
What is the torque about the origin?
A) r F sin
B) r F cos
C) zero
origin
Clicker Question
Room Frequency BA
Two light (massless) rods, labeled A and B,
each are connected to the ceiling by a
frictionless pivot as shown. Both rods are
released from a horizontal position.
Which one experiences the larger torque?
A) A
B) B
C) Same
I
2
m
r
 ii
i
θ
F  mg sin 
θ Fg = mg
 A  F L  Lmg sin 
L
 B  2mg sin   Lmgsin 
2
Clicker Question
Room Frequency BA
Two light (massless) rods, labeled A and B,
each are connected to the ceiling by a
frictionless pivot as shown. Both rods are
released from a horizontal position.
Which one has the larger moment of inertia?
A) A
B) B
C) Same
2
I A  mL
2
1 2
 L
IB  (2m)    mL
 2
2
I
2
m
r
 ii
i
Clicker Question
Room Frequency BA
A small wheel and a large wheel are connected by a belt.
The small wheel turns at a constant angular velocity ωS.
There is a bug S on the rim of the small wheel and a bug
L on the rim of the big wheel? How do their speeds
compare?
A) vS = vL
B) vS > vL
C) vS < vL
Room Frequency BA
Clicker Question
A rock of mass m is twirled on a
string in a horizontal plane.
The work done by the tension in the string on the rock is
T
A) Positive
B) Negative
C) Zero
The work done by the tension force
is zero, because the force of the
tension in the string is perpendicular
to the direction of the displacement:
W = F cos 90°= 0
Clicker Question
Room Frequency BA
Roller Coaster Problem
N Fnet,y = N-mg = may = mv2/r
v
mg
Approximately circular arc
If the car moving rightward at the top of this hill:
A) The net force on the car is upward.
B) The net force on the car is downward
C) The net force on the car is zero
Clicker Question
Room Frequency BA
Two paths lead to the top of a big hill.
Path #1 is steep and direct and Path #2 is twice as long but less steep.
Both are rough paths and you push a box up each.
How much more potential energy is gained if you take the longer path?
A) none
B) twice as much
C) four times as much
D) half as much
d
h
#1
2d
h
θ
d 2  h2
#2
φ
4d 2  h 2
PE  mgh in both cases.
Clicker Question
Room Frequency BA
A big ball of mass M = 10m and speed v strikes a small
ball of mass m at rest.
After the collision, could
the big ball come to a
complete stop and the
small ball take off with
speed 10 v?
A) Yes this can occur
B) No, because it violates
conservation of
momentum
C) No, because it violates
conservation of energy
pinitial  (10 m)v  10 mv
p final  m(10v)  10mv
1
KEinitial  (10 m)v 2  5mv 2
2
1
2
2
KE final  m(10 v)  50 mv
2