Question

A 5 kg fish swimming at 1 m/s swallows an absentminded 500 g fish swimming toward it at a veloc- ity that brings both fish to a halt immediately after lunch. What is the velocity of the approaching smaller fish before lunch?

Answer 1

v = 10 m/s

Step-by-step explanation:

given,

Mass of large fish, M = 5 Kg

speed of swimming, v' = 1 m/s

mass of small fish, m = 500 g = 0.5 Kg

speed of the fish = v

using conservation of momentum

m v + M v' = M u' + m u

final speed of both the speed is zero.

- 0.5 x v + 5 x 1 = 0

negative sign is used because small fish is moving in opposite direction.

now,

0.5 v = 5

v = 10 m/s

hence, the speed of the small fish is equal to 10 m/s.