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Just before hitting the ground, a rubber superball has a downward velocity of 7.

ID: 2058836 • Letter: J

Question

Just before hitting the ground, a rubber superball has a downward velocity of 7.67 m/s. Immediately after bouncing, the upward velocity is 3.53 m/s. If the ball's mass is 100g, and the average force on it while in contact with the ground was Favg = 112 N in the positive Y direction, how long was the ball in contact with the ground? Give your answer in milliseconds.


I worked out the problem and got that it equals 10 milliseconds. If someone could confirm or disagree with me with their own calculations I would appreciate it. I will rate lifesaver :)

Explanation / Answer

Force = rate of change of momentum

F = dp/dt

=> dt = dp/F = 0.1(3.53+7.67)/112 = 10 ms