Physic Momentum And Moments?

Question

A man wearing a bullet proof vest stands still on roller skates. the total mass is 80kg. a bullet of mass 20g is fired at 400m/s. it is stopped by the vest and falls to the ground

1.what is the velocity of the man

2.how does this compare to what you see in TV/ films

Answer 1

m1*u1 + m2*u2 = m1*v1 + m2*v2

.02 g*400 m/s + 80 kg*0 = .02 g*0 + 80 kg*v2

Solve for v2.