A 5-kg fish swimming at a speed of 1 m/s swallows an absent-minded 1-kg fish at rest.The speed of the larger fish after lunch is

Question

Quizplus · Accepted Answer

The conservation of momentum can be used to solve the problem. Before lunch, the total momentum of the system is (5 kg)(1 m/s) + (1 kg)(0 m/s) = 5 kg·m/s. After lunch, the total momentum is (6 kg)(v), where v is the speed of the larger fish. Since momentum is conserved, we have 5 kg·m/s = 6 kg·v, which gives v = 5/6 m/s. Therefore, the answer is (C).

A 5-Kg Fish Swimming at a Speed of 1 M/s