Question

A body at rest breaks into two pieces of equal masses. The parts will move 

(a) in same direction 

(b) along different lines 

(c) in opposite directions with equal speeds 

(d) in opposite directions with unequal speeds.

Answer 1

(c) in opposite directions with equal speeds 

Explanation: 

Let the velocities of two parts be v and v' and mass of each part = m. Momentum before the break = 2m*0 = 0. 

Momentum after the break =mv+mv'. Since there is no external force on the body, the linear momentum will be conserved.

 →mv+mv' = 0 

→v = -v'

So the parts will move in opposite directions with equal speeds.