Question

A body is moving with a velocity v, breaks up into two equal parts.One of the part retraces back with velocity v. Then the velocity of the other part is ? :-

(A) v in forward direction

(B) 3v in forward direction

(C) v in backward direction

(D) 3v in backward direction

Answer 1

B. `3v` in forward direction

Explanation:

As,no external force is acting here,we can apply the law of conservation of momentum.

Initial momentum =`m*v` (where, `m` is the mass of the whole body)

Considering initial direction of movement of the whole mass to be positive.

Final momentum = `-m/2 *v + m/2 *u` (after the breakage, let the other mass will run with a velocity of `u` in the initial direction of the velocity of the whole mass)

So,we can say,

`mv = -m/2 v +m/2 u`

So, `u=3v`