1. The problem statement, all variables and given/known data Two kids on roller skates push off each other in opposite directions. One weighs 36kg and he rolls 15m before stopping, the other weighs 24kg, how far does he move before stopping? Assume they experience the same frictional force by the path - assume friction force is negligible during the time the push each other away - This involves both momentum and work energy. 2. Relevant equations From the question I assume this involves conservation of momentum equations and a work-energy equation (but i don't know any!) 3. The attempt at a solution I tried to use straight line motion equations but we are not given initial velocity, then I tried to use momentum equations but couldn't and am now at a loss.