Question

A bullet of mass 20 g is fired horizontally with a velocity of 150 m/s from a pistol of mass 2 kg. Find the recoil velocity of the pistol.

Answer 1

Given, Mass (m₁) of bullet = 20 g = 0.02 kg 

Mass (m₂) of pistol = 2 kg 

Initially bullet is inside the gun and it is not moving.

Mass = m₁ + m₂ = (0.02 + 2) kg = 2.02 kg 

And u₁ = 0 

So, Initial momentum = 2.02 × 0 = 0 .....(i)

Finally let the velocity of pistol be v₂ and v₁ for bullet = 150

Final momentum = m₁v₁ + m₂v₂ 

= 0.02 × 150 + 2v₂ ...(ii) 

We know that 

Initial momentum = Final momentum