A .01 kg bullet leaves a 4kg rifle with a velocity of 850m/s. What is the rifle's momentum? What is the recoil velocity of the rifle?

rifles-momentum
recoil-velocity

#1

A .01 kg bullet leaves a 4kg rifle with a velocity of 850m/s. What is the rifle’s momentum? What is the recoil velocity of the rifle?

Answer:

we know law of conservation of momentum.
Applying this law,
MbVb=MrVr
Mb= Mass of bullet = 0.01kg
Vb= Velocity of bullet=850 m/s
Mr= Mass of rifle= 4 kg
Vr = Velocity of rifle

Hence,
0.01 * 850 = 4 * Vr

So Vr = 2.125 m/s
so Recoil velocity of rifle= 2.125 m/s

Momentum of rifle= Momentum of bullet= 4*2.125 =8.5 kg m/s