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Multiple Choice (5 points each):
1) A spring in a dart gun is compressed 2cm. It is then used to fire a dart which has kinetic energy K.
The spring is then compressed to 4cm. What is the new kinetic energy of the dart when fired?
a) K
b) 2K
c) 4K
d) K/2
e) K/4
2) A heavy and light marble leave a marble gun with the same initial velocity and are fired towards
identical springs. Which marble compresses its spring more?
a) The heavy one
b) The light one.
c) They both compress the springs the same amount.
d) Not enough information to tell.
3) Identical balls are fired off a cliff of height H. The red ball is fired straight up into the air with initial
speed v0 while the blue ball is fired straight down with initial speed v0. Which ball has the greatest speed
right before it hits the ground?
a) The red ball.
b) The blue ball.
c) Both balls have the same final speed.
d) Not enough information to tell.
4) A spring in a dart gun is compressed 2cm. It is then used to fire a dart which has an initial speed of s.
The spring is then compressed to 4cm. What is the new initial speed of the dart when fired?
a) s
b) 2s
c) 4s
d) s/2
e) s/4
5) A heavy and a light marble are released from rest on identical ramps from the same height.
Which marble has the greatest speed right before it lands?
a) The heavy one.
b) The light one.
c) They have the same final speed.
d) Not enough information to tell.
6) Identical red and blue balls are launched with the same initial velocity. Their trajectories are shown
below. How do the final mechanical energies of the balls compare at their maximum height?
a)
b)
c)
d)
The red ball has more mechanical energy.
The blue ball has more mechanical energy.
The balls have the same mechanical energy.
Not enough information to tell.
7) A heavy and a light marble are released from rest on identical ramps from the same height.
Which marble has the greatest momentum right before it lands?
a) The heavy one.
b) The light one.
c) They have the same final momentum
d) Not enough information to tell.
8) A man stands on a cart supported by frictionless rails as shown. He throws balls onto a rigidly
mounted panel affixed to the cart. The balls rebound and fly off backwards.
a) the cart will move to the right.
b) the cart will move to the left.
c) the cart will stay still.
9) A ball of putty with mass M is fired at initial velocity v to the right towards an identical mass of putty
at rest. The two putty balls stick together. What is the final velocity of the pair?
a) v to the right
b) v to the left
c) zero
d) v/2 to the right
e) v/2 to the left
10) Identical red and blue balls are launched with the same initial velocity. Their trajectories are shown
below. How do the final mechanical energies of the balls compare?
a)
b)
c)
d)
The red ball has more mechanical energy at the end.
The blue ball has more mechanical energy at the end.
The balls have the same mechanical energy at the end.
Not enough information to tell.
Extra Credit Questions (5 points each):
11) A box moves along a ramp with a coefficient of friction, μs.
As the box moves along the ramp
a) negative work is done on the box by friction
b) positive work is done on the box by friction
c) no work is done on the box by friction
d) it depends on whether the box is going up or down the ramp
12) A basketball bounces on the floor as shown. Which statement below is true?
V0
V0
300
300
a) the momentum of the basketball parallel to the floor is conserved.
b) the momentum of the basketball perpendicular to the floor is conserved.
c) the total momentum of the basketball is conserved.
d) none of the momentum components of the basketball conserved.
Long Problem #1 (25 points):
A hockey puck with mass M rests on the surface of an ice rink. Another puck with mass 2M moving with
velocity V=10m/sec towards the right hits the first puck and both go flying off in different directions.
The lighter puck has a final velocity of 12m/sec directed 300 above the horizontal. Find the velocity of
the heavy puck (magnitude and direction.)
12 m/sec
M
300
2M
2M
10 m/sec
before
collision
collision
after collision
Long Problem #2 (25 points):
A bullet with mass (m=0.02kg) is fired with a velocity of (200m/sec) into a stationary block of wood
(M=1.98kg) into which the bullet lodges. The block is suspended on a 5m long cable which allows it to
swing upwards after the impact. What is the maximum height above its starting point that the block
achieves?