1. The problem statement, all variables and given/known data I have two blocks attached by a string (massless) over a pulley (frictionless, massless). Block 2 (which weighs less than block one) is released and the two blocks meet momentarily at the same height. I have the find the speed at which the meet at that moment. The blocks are separated by a distance of 1m. I have drawn a figure in paint (sorry for this pic): http://i36.tinypic.com/2076at1.png 2. Relevant equations Emechf = Emechi Emech = Ug + K 3. The attempt at a solution Emechf = Emechi <=> (m_1gh + m_2gh) + (1/2m_1v^2 + 1/2m_2v^2) = m_1gH (where H = 1m, and h is the height at which they meet) But then I have this h which is unkown and I can't figure out. Thanks a lot in advance.