A boy on roller blades throws a jug of water away from himself, giving it a speed of 10 m/s. The boy's mass is 50 kg and the mass of the jug and water is 9 kg. What is the velocity gained by the boy?

Question

A boy on roller blades throws a jug of water away from himself, giving it a speed of 10 m/s.  The boy's mass is 50 kg and the mass of the jug and water is 9 kg.  What is the velocity gained by the boy?

bobpursley · Answer

momentum is conserved. initialmomentum=finalmomentum 0=9(10)+50V solve for V. Notice its direction (sign).