Question

A swimming fish has a momentum of 8 kg-m/s. It eats a stationary 2 kg fish and keeps

swimming. What is their new momentum?
a. Zero
b. 10 kg-m/s
c. 8 kg-m/s
d. 16 kg-m/s

Answer 1

C

Step-by-step explanation:

Using law of conservation of momentum of the system

Momentum before = momentum after

8 kg m/s = 8 kg m/s

The second fish has zero momentum, so after eating it the system still has momentum of 8 kg m/s

Answer 2

d. 16 kg-m/s

Step-by-step explanation:

The new momentum of the swimming fish after eating the stationary fish can be calculated by adding the momentum of the initial swimming fish and the momentum of the stationary fish. Since momentum is a vector quantity, the direction of the momentum is the same as the direction of motion of the fish. If the fish continues to swim with the same velocity after eating the stationary fish, then the new momentum is the sum of the initial momentum of the swimming fish and the momentum of the stationary fish.

Initial momentum of swimming fish = 8 kg-m/s

Momentum of stationary fish = 2 kg * 0 m/s = 0 kg-m/s

New momentum = Initial momentum of swimming fish + Momentum of stationary fish = 8 kg-m/s + 0 kg-m/s = 8 kg-m/s + 2 kg-m/s = 10 kg-m/s.

So, the correct answer is (d) 16 kg-m/s.