# SAT Physics Practice Test: Linear Momentum

### Test Information

9 questions

7 minutes

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1. An object of mass 2 kg has a linear momentum of magnitude 6 kg • m/s. What is this object’s kinetic energy?

A. 3 J
B. 6 J
C. 9 J
D. 12 J
E. 18 J

2. A ball of mass 0.5 kg, initially at rest, acquires a speed of 4 m/s immediately after being kicked by a force of strength 20 N. For how long did this force act on the ball?

A. 0.01 s
B. 0.02 s
C. 0.1 s
D. 0.2 s
E. 1 s

3. A box with a mass of 2 kg accelerates in a straight line from 4 m/s to 8 m/s due to the application of a force whose duration is 0.5 s. Find the average strength of this force.

A. 2 N
B. 4 N
C. 8 N
D. 12 N
E. 16 N

4. A ball of mass m traveling horizontally with velocity v strikes a massive vertical wall and rebounds back along its original direction with no change in speed. What is the magnitude of the impulse delivered by the wall to the ball?

A. 0
B. mv
C. mv
D. 2mv
E. 4mv

5. Two objects, one of mass 3 kg and moving with a speed of 2 m/s and the other of mass 5 kg and speed 2 m/s, move toward each other and collide head-on. If the collision is perfectly inelastic, find the speed of the objects after the collision.

A. 0.25 m/s
B. 0.5 m/s
C. 0.75 m/s
D. 1 m/s
E. 2 m/s

6. Object #1 moves toward object #2, whose mass is twice that of object #1 and which is initially at rest. After their impact, the objects lock together and move with what fraction of object #1’s initial kinetic energy?

A.
B.
C.
D.
E. None of the above

7. Two objects move toward each other, collide, and separate. If there was no net external force acting on the objects, but some kinetic energy was lost, then

A. the collision was elastic and total linear momentum was conserved
B. the collision was elastic and total linear momentum was not conserved
C. the collision was not elastic and total linear momentum was conserved
D. the collision was not elastic and total linear momentum was not conserved
E. None of the above

8. A wooden block of mass M is moving at speed V in a straight line.

How fast would the bullet of mass m need to travel to stop the block (assuming that the bullet became embedded inside)?

A. mV/(m + M)
B. MV/(m + M)
C. mV/M
D. MV/m
E. (m + M)V/m

9. Which of the following best describes a perfectly inelastic collision free of external forces?

A. Total linear momentum is never conserved.
B. Total linear momentum is sometimes (but not always) conserved.
C. Kinetic energy is never conserved.
D. Kinetic energy is sometimes (but not always)conserved.
E. Kinetic energy is always conserved.

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