A ‘m’ kg fish swimming at 2 m/s …

A ‘m’ kg fish swimming at 2 m/s catches a ‘m/9’ kg fish coming towards it from opposite direction swimming at 3 m/s. The velocity of the larger fish immediately after the grab is:

(A) 1.5ˆi m/s
(B) 2.1ˆi m/s
(C) 1.5ˆi m/s
(D) 2.1ˆi m/s

Solution

This can be considered as inelastic collision. Using conservation of linear momentum along x-direction,

2m3m9=(m+m9)v

213=109v

v=1.5m/s

Hence, (A)