Question

A bullet of mass 10g is fired horizontally with a velocity 200m/s from a pistol of mass 2kg.calculate the recoil velocity of the pistol

Answer 1

Applying law of conservation of linear momentum for bullet (mass $m_1=10 grms$ , velocity, $v_1=200 m/s$  ) and pistol (mass $m_2=2 kg$ , velocity, $v_2 m/s$  ) as follows

$m_1v_1+m_2v_2=0 \quad \text{(in the direction of motion of bullet)}$    

$10\times 200+2000\times v_2=0$  

$v_2 =-1m/s$

The above negative value shows that the pistol will recoil with a velocity 1 m/s backwards (opposite direction to the motion of bullet)