1. The problem statement, all variables and given/known data Two masses, A and B, lie on a frictionless table. They are attached to either end of a light rope of length l which passes around a pulley of negligible mass. The pulley is attached to a rope connected to a hanging mass, C. We are supposed to find the accelerations of A, B and C. 3. The attempt at a solution I'm sorry that I don't have the time to write out my detailed working. I didn't get the answer required. But I notied that the solution given (page 5 from http://hep.uchicago.edu/cdf/frisch/p141/ps4_solutions.pdf) simply states [tex]M_A a_A = T[/tex] and so on. My other equations, like the kinematic constraint (relation between ac, aa, and ab) and the equation of motion for mass C is ok. We need 4 equations to solve. So 2 are ok. My equations for MA and MB are different from the solution here. I have assumed that M_A is in a frame that is accelerating at a rate equal to a_C, in addition to the tension imparted on mass A. Same for B. Can I do it like I have done here, or is this totally wrong?