Question

What is the formula for recoil velocity of the gun ?

Answer 1

After firing the bullet, the bullet moves forward with a large momentum and the gun moves backward with an equal momentum. 

Let m and M be the masses of bullet and gun,respectively. If v and V are the velocities of the bullet and gun, respectively after the firing then:- 

0= mv+ MV 

Therefore V=-mv/M 

The negative sign indicates that the gun moves in a direction to that of the bullet.