The muzzle velocity of a 50.0 g shell leaving a 3.00 kg rifle is 400. m/s. What is

the recoil velocity of the rifle?

-6.67 m/s

Explanation:

Momentum before = momentum after

m₁ u₁ + m₂ u₂ = m₁ v₁ + m₂ v₂

(0.0500 kg) (0 m/s) + (3.00 kg) (0 m/s) = (0.0500 kg) (400. m/s) + (3.00 kg) v

0 kg m/s = 20 kg m/s + (3.00 kg) v

v = - 6.67 m/s