Practice Questions
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| 1. |
An
athlete of mass 70.0 kg applies a force of 500 N to a 30.0 kg luge,
which is initially at rest, over a period of 5.00 s before jumping
onto the luge. Assuming there is no friction between the luge and
the track on which it runs, what is its velocity after the athlete
jumps on? |
| (A) |
12.5 m/s |
| (B) |
25.0 m/s |
| (C) |
35.7 m/s |
| (D) |
83.3 m/s |
| (E) |
100 m/s |
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| 2. |
The graph above shows the amount
of force applied to an initially stationary 20 kg curling rock over time.
What is the velocity of the rock after the force has been applied
to it? |
| (A) |
1.25 m/s |
| (B) |
5 m/s |
| (C) |
10 m/s |
| (D) |
25 m/s |
| (E) |
50 m/s |
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| 3. |
A 60 kg man holding a 20 kg box
rides on a skateboard at a speed of 7 m/s. He throws the box behind him,
giving it a velocity of 5 m/s. with respect to the ground. What
is his velocity after throwing the object? |
| (A) |
8 m/s |
| (B) |
9 m/s |
| (C) |
10 m/s |
| (D) |
11 m/s |
| (E) |
12 m/s |
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| 4. |
A scattering experiment is done
with a 32 kg disc and two 8 kg discs on a frictionless surface.
In the initial state of the experiment, the heavier disc moves in
the x direction with velocity v =
25 m/s toward the lighter discs, which are at rest. The discs collide
elastically. In the final state, the heavy disc is at rest and the
two smaller discs scatter outward with the same speed. What is the x-component
of the velocity of each of the 8 kg discs in the final state? |
| (A) |
12.5 m/s |
| (B) |
16 m/s |
| (C) |
25 m/s |
| (D) |
50 m/s |
| (E) |
100 m/s |
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| 5. |
An
moving object has kinetic energy KE = 100 J and
momentum p = 50 kg · m/s. What is its mass? |
| (A) |
2 kg |
| (B) |
4 kg |
| (C) |
6.25 kg |
| (D) |
12.5 kg |
| (E) |
25 kg |
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| 6. |
An object of mass m moving
with a velocity v collides with another object
of mass M. If the two objects stick together, what
is their velocity? |
| (A) |
 |
| (B) |
 |
| (C) |
 |
| (D) |
 |
| (E) |
Zero |
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| 7. |
A
body of mass m sliding along a frictionless surface
collides with another body of mass m, which is stationary
before impact. The two bodies stick together. If the kinetic energy
of the two-body system is E, what is the initial
velocity of the first mass before impact? |
| (A) |
 |
| (B) |
 |
| (C) |
 |
| (D) |
 |
| (E) |
 |
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| 8. |
A
hockey puck of mass m is initially at rest on a
frictionless ice rink. A player comes and hits the puck, imparting
an impulse of J. If the puck then collides with
another object of mass M at rest and sticks to it,
what is the final velocity of the two-body system? |
| (A) |
 |
| (B) |
 |
| (C) |
 |
| (D) |
 |
| (E) |
 |
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Questions 9 and 10 refer to two 1 kg
masses moving toward each other, one mass with velocity  = 10 m/s, the other with velocity
 = 20 m/s.
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| 9. |
What is the velocity of the center
of mass? |
| (A) |
0 m/s |
| (B) |
5 m/s to the left |
| (C) |
10 m/s to the left |
| (D) |
15 m/s to the left |
| (E) |
20 m/s to the left |
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| 10. |
What is
the total energy of the system? |
| (A) |
50 J |
| (B) |
150 J |
| (C) |
200 J |
| (D) |
250 J |
| (E) |
400 J |
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