# 1200 kg car moving to the right with a speed of 25m/s

For the following problems, the answers are given. Show the calculations to arrive at the correct answers.

1. 1200 kg car moving to the right with a speed of 25m/s collides with a 1500 kg truck and locks bumpers with the truck. Calculate the velocity of the combination after the collision if the truck is initially (a) at rest, (b) moving to the right with a speed 20 m/s, (c) moving to the left with a speed of 20 m/s.

Answer: (a) 11m/s to the right (a) 22 m/s to the right (c) v = 0, or it is at rest

2. A new crowd control method utilizes "rubber" bullets instead of real one. Suppose that, in a test, one of these "bullets" with a mass of 500 g is travelling at 250 m/s to the right. It hits a stationary target head on. The targets mass is 25 kg and it rests on a smooth surface. The bullet bounces backwards (to the left) off the target at 100 m/s.

(a) Which way must the target move after the collision: (1) right, (2) left, (3) it could be stationary, or (4) you can't tell from the data given?

(b) Determine the recoil speed of the target after the collision.

Answer: (a) the target must move to (1) right to conserve the total momentum. (b) 7 m/s

3. A moving shuffleboard puck has a glancing collision with a stationary puck of the same mass. If friction in negligible, what are the speeds of pucks after the collision?

Answer: V1 = 0.61 m/s, and V2 = 0.73 m/s

4. A dropped rubber ball hits the floor with a speed of 8 m/s and rebounds to a height of 0.25 m. What fraction of the initial kinetic energy was lost in the collision?

Answer: 0.92 or 92%

5. 1 kg object moving 2m/s collides elastically with a stationary 1kg object. How far will the initially stationary object travel along a 37 degree inclined plane?(neglect friction)

Answer: 0.34 m

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#### Solution Summary

Apply momentum conservation