posted by CiNdY .
A 50-kg woman and a 25-kg boy stand motionless facing each other on friction-free roller blades. The woman pushes the boy, who moves away at a speed of 5.0 m/s. What is the woman’s speed in the opposite direction?
Here's a clue (from the law of cnservation of momentum)
Their momenta are equal and opposite, so that the total momentum remains zero.
M1*V1 = -M2*V2
V2/V1 = ?