A bullet of mass 6 g is fired with a velocity of 500 m`cdot s^(-1)` from a gun of mass 4 kg. Find the recoil velocity of gun.

Explanation

As the bullet and the gun were at rest before the firing, the initial momentum of the system was zero. Let the speed of the bullet after the firing be v, and that of the gun be V.
From the law of conservation of linear momentum, we get,
0 = MV + mv
[ mass of the bullet = m, mass of the gun = M]
or, V = `-(m)/(M)v = - (6xx10^(-3))/(4) xx 500 = - 0.75 m cdot s^(-1)`.
Hence, recoil velocity of the gun = 0.75 `m cdot s^(-1)`.