A bowling ball, moving to the east at a speed of 1.4 m/s, collides head-on with a stationary beach ball of the same diameter but less than one twentieth the mass. After the collision, the beach ball moves with a speed of 1.6 m/s. Which of the following is then true?
A) The bowling ball has a velocity of slightly under 1.4 m/s, to the east.
B) The beach ball has more momentum than the bowling ball.
C) The bowling ball recoils to the west with nearly the same speed as before the collision.
D) The bowling ball and the beach ball have the same momentum after the collision.

Question

Quizplus · Accepted Answer

Since momentum is conserved in the collision and the beach ball is less than one twentieth the mass of the bowling ball, the bowling ball must have more momentum both before and after the collision. Therefore, B and D are incorrect. Additionally, since momentum is conserved in the collision, the total momentum before the collision (the momentum of the bowling ball) must be equal to the total momentum after the collision (the momentum of both balls). This means that the bowling ball's momentum after the collision must be less than its momentum before the collision, which means that it must be moving slower than 1.4 m/s to the east. Therefore, A is the correct answer. Lastly, C is incorrect because the bowling ball will recoil to the west, not the east.

A Bowling Ball, Moving to the East at a Speed