A 50.0-kg person stands on a 200-kg raft, which is at rest. She starts to walk on the raft with a speed of 3.00 m/s with respect to the raft. What is the speed of the person relative to the water?
A) 2.40 m/s
B) 0.225 m/s
C) 0.500 m/s
D) 0.750 m/s
E) 1.20 m/s

Question

Quizplus · Accepted Answer

The momentum of the person relative to the water is equal to the momentum of the person relative to the raft plus the momentum of the raft relative to the water. Since the raft is at rest relative to the water, the momentum of the person relative to the water is equal to the momentum of the person relative to the raft. Therefore, the speed of the person relative to the water is equal to the speed of the person relative to the raft, which is 3.00 m/s.

A 500-Kg Person Stands on a 200-Kg Raft, Which Is at at Rest