1. The problem statement, all variables and given/known data I have 2 blocks of mass M one on a frictionless horizontal surface the other hanging over the edge of the surface connected by a string of length l. The string goes over a pulley of mass m. Find the acceleration. 2. Relevant equations PE = mgh KE = 1/2mv^2 3. The attempt at a solution I know how to do the problem without the pulley having any mass how do you factor in the pulley's mass?