1. The problem statement, all variables and given/known data Two small balls are suspended side by side from two strings of length L so that they just touch when in their lowest positions. Their masses are m and 2m, repectively. If the left ball (of mass m) is pulled aside and released from a height h, it will swing down and collide with the right ball (of mass 2m) at the lowest point. Both balls again swing down, and they collide once more at the lowest point. How high will each swing after this second collision? Assume both collisions are elastic. 2. Relevant equations So, for now, I'm just using: mv1 +mv2 = mv1' + mv2' Ek = 0.5mv^2 Ep = mgh 3. The attempt at a solution So I know v2 = 0, but I'm not sure if v1 would also be 0. For ball#1 (mass m), Ek = Ep => 0.5v1'^2 = mgh Sort of stuck as with what to do next... Any help is appreciated.