Here we apply Newton's Second Law to a system of two blocks that are suspended from two pulleys. One block is tied directly to a string but the other block is suspended from a pulley that moves along the string. Calculate the ratio of masses that will keep the system in static equilibrium. Calculate the acceleration of the system when the blocks are not in equilibrium. This problem comes up in introductory physics courses such as AP Physics and early college physics. It also serves as the foundation for problems that appear on the JEE and A Levels.