[SOLVED] Slide and Collide. I need help getting started on this. A block of mass 12 kg lies at a vertical height 7.3 m on a frictionless incline plane. It slides down the plane and collides elastically with a second block whose mass is 6.8 kg. Find the final velocities of the two blocks. so far I got: (1/2)M1V1^2 = (1/2)M1V2 ^2 + (1/2)M V2 = ((M1V1^2) - (M1V1^2))/M2. I am not sure where to start.