posted by cassie .
A 0.105-kg hockey puck moving at 26 m/s is caught and held by a 72-kg goalie at rest. With what speed does the goalie slide on the ice?
Mpuck*Vpuck = (Mpuck+Mgoalie)*Vfinal
Vfinal = (0.105/72.1)*26 m/s
It's called momentum conservation
It assumes that goalie is not in contact with the goal