A rifle of mass 2 kg is horizontally suspended by a pair of strings so that recoil can be measured. The rifle fires a bullet of mass 1/100 kg at a speed of 200 m/s. The recoil velocity of the rifle is about

Question

Quizplus · Accepted Answer

Using conservation of momentum:
Before firing:
total momentum = 0
After firing:
Initial momentum of rifle = -Final momentum of rifle
(mass of rifle) x (recoil velocity) = -(mass of bullet) x (bullet velocity)
(2 kg) x (recoil velocity) = -(0.01 kg) x (200 m/s)
recoil velocity = -1 m/s (negative sign indicates direction opposite to bullet)

A Rifle of Mass 2 Kg Is Horizontally Suspended by a Pair