1. The problem statement, all variables and given/known data 2. Relevant equations 1.) m1*v1 + m2*v2 = m1'*v1' + m2'*v2' Where the ' denotes the velocity/mass after the event/whatever. 2.) 0.5m1(v1)^2 + 0.5m2(v2)^2 = 0.5m1'(v1')^2 + 0.5m1'(v1')^2 3. The attempt at a solution I know its a conservation of momentum style of problem, but my professor does an awful job of teaching IMO. Give me a nudge in the right direction, and I'll see what I can do from there.