The bullet is fired from the rifle at a speed of 860 m / s. Determine the recoil velocity of the rifle

The bullet is fired from the rifle at a speed of 860 m / s. Determine the recoil velocity of the rifle if the weights of the bullet and rifle are 9 g and 4.5 kg, respectively.

Given:

m1 = 9 grams = 0.009 kilograms – the mass of the bullet that flew out of the rifle;

m2 = 4.5 kilograms – the mass of the rifle;

v1 = 860 m / s – bullet speed.

It is required to determine the speed of the rifle at recoil v2 (m / s).

According to the law of conservation of momentum (momentum):

m1 * v1 = m2 * v2;

v2 = m1 * v1 / m2 = 0.009 * 860 / 4.5 = 7.74 / 4.5 = 1.72 m / s.

Answer: the recoil speed of the rifle will be 1.72 m / s.