Question

A grenade is thrown in a horizontal direction with a velocity of 10m/sec and explodes into two parts weighing 1 kg-wt and 1.5kg-wt. The velocity of the larger fragment remains horizontal after the explosion and increases to 25m/sec. Find the velocity and direction of flight of the smaller fragment.

Answer 1

Explanation:

The sum of the momenta of the grenade fragments before the explosion is m₁v₀ + m₂v₀ and after the explosion m₁v₁ + m₂v₂; since the change in the momenta of the grenade fragments results only from internal forces, then, according to the law of conservation of momentum 

m₁V₀  + m₂V₀ = m₁V₀ + m₂V₂,

The minus sign before the velocity indicates that after the explosion the smaller fragment moves in a direction opposite to the initial motion of the grenade.