A 75.0-kg swimmer dives horizontally off a 465-kg raft initially at rest.If the diver's speed immediately after leaving the raft is 5.00 m/s,what is the corresponding raft speed?
A)31.0 m/s
B)375 m/s
C)0.806 m/s
D)1.24 m/s
E)5.00 m/s

Question

Quizplus · Accepted Answer

We can use the conservation of momentum to solve this problem: 
Before the diver jumps: 
Total momentum = 0 (since the raft is initially at rest)

After the diver jumps: 
Momentum of the diver = 75.0 kg x 5.00 m/s = 375 kg m/s 
Momentum of the raft = 465 kg × v 
Total momentum = 375 kg m/s + 465 kg × v

Since momentum is conserved, we can set the before and after momenta equal to each other:

0 = 375 kg m/s + 465 kg × v

Solving for v, we get: 
v = -375 kg m/s ÷ 465 kg 
v = -0.806 m/s

The negative sign indicates that the raft is moving in the opposite direction of the diver, which makes sense since the diver is pushing off of the raft. Therefore, the answer is C) 0.806 m/s.

A 750-Kg Swimmer Dives Horizontally Off a 465-Kg Raft Initially at at Rest.If