From a rifle of mass 4 kg, a bullet of mass 50 g is fired with an initial velocity of 35 ms-1, calculate the initial recoil velocity of the rifle.

From a rifle of mass 4 kg, a bullet of mass 50 g is fired with an init

1.	From a rifle of mass 4 kg, a bullet of mass 50 g is fired with an initial velocity of 35 ms-1, calculate the initial recoil velocity of the rifle.
Answer» Mass of the gun M = 4 kg. Mass of bullet M = 50 g = 50 × 10^-3kg. Initial velocity of the bullet v = 35ms^-1 Let recoil velocity of the gun be vms^-1 Before firing the bullet both gun and bullet were in rest so total momentum of gun and bullet is zero, After firing Momentum of bullet = mv, Momentum of gun = Mv Total momentum of bullet and gun after firing = mv + Mv Since there is no external force applied on the system. So total momentum after firing = total momentum before firing mv + Mv = 0 Mv = -mv fi V = \(\frac{mv}{M}= \frac{50\times 10^{-3}\times 35}{4}\) = -0.44 ms^-1 Here negative sign shows that there recoil velocity of the gun is in the direction opposite to the velocity of the bullet.