A bomb of mass 6 kg initially at rest explodes into two fragments of masses of 4 kg and 2 kg, respectively. If the greater mass moves with a velocity of 5 m s^–1, find the velocity of the 2 kg mass.

Given, M₁ = 4 kg, M₂ = 2 kg

Since the bomb is initially at rest, U = 0.

∴ Its initial momentum = MU = 6 × 0 = 0

v₁ = 5 m s⁻¹, v₂ =?

Using the law of conservation of momentum

MU = m₁v₁ + m₂v₂

0 = 4 × 5 + 2 × v₂

i.e., 0 = 20 + 2 × v₂

∴ v₂ = - 20/2 = - 10 m/s

-ve sign of v₂ implies that 2 kg mass moves in the direction opposite to 4 kg mass.