A 75-kg man is riding in a 30-kg cart at 2.0 m/s.He jumps off in such a way as to land on the ground with no horizontal velocity.The resulting change in speed of the cart is:
A)0 m/s
B)2.0 m/s
C)3.0 m/s
D)5.0 m/s
E)7.0 m/s

Question

Quizplus · Accepted Answer

When the man jumps off the cart, he exerts an impulse on the cart, causing it to change speed. Using conservation of momentum: (75 kg + 30 kg) * 2.0 m/s = 30 kg * v_cart. Solving for v_cart gives 7.0 m/s. The change in speed is 7.0 m/s - 2.0 m/s = 5.0 m/s.

A 75-Kg Man Is Riding in a 30-Kg Cart at 2.0