1. The problem statement, all variables and given/known data m1= 3kg m2= 6kg v1 = 5m/s v2= 2m/s d = 3m DIAGRAM : http://gyazo.com/17b3126726b109256a35f65b86708bb0 2. Relevant equations Conservation of momentum: m1+v1 = m1v1'+m2v2' Conservation of elastic: m1v1^2+m2v2^2 = m1v1'^2+m2v2'^2 3. The attempt at a solution Now my attempt was use both equations & the answers I've gotten so far are 27=3v1'+6v2'(for conservation of momentum) & the 2nd one I've got for the conservation of elastic is 99= 3v1'^2 + 6v2'^2 since they will collide at some point. The only thing I'm stuck at is what to do next afterwards. My teacher has done a similar question but I can never understand how he did it.