SAT Subject Physics Practice Question 346: Answer and Explanation

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Question: 346

42. A professional golfer strikes a golf ball with his driver, imparting a momentum of 8 kg·m/s on the ball. The golf ball strikes a wall and maintains contact for .0025 seconds before it bounces straight backward at the same velocity with which it struck the wall. The momentum of the golf ball is

A. 6400 kg·m/s
B. 3200 kg.·m/s
C. 8 kg·m/s
D. .02 kg·m/s
E. .01 kg·m/s

Correct Answer: C


The correct answer is (C). The collision described in the problem is perfectly elastic because the golf ball had the same velocity when it rebounded from the wall as when it struck the wall. Momentum is conserved perfectly, so the golf ball must have the same momentum after the collision with the wall as it had when it approached the wall before the collision.

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