**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,

Mb*Vb=Mr*Vr

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