1. The problem statement, all variables and given/known data I have two equations. The first is for all of the forces on a hanging mass from a pulley. The second is for the sum of the torques about the pulley from which the mass hangs. I simply have to combine the equations to find the acceleration of the object. I have attempted every algebraic manipulation I can think of and keep coming out with the wrong answer. Please help. 2. Relevant equations T-mg=ma (for the sum of forces on the hanging mass) Tr=I(-a/r) (for the torques about the pulley) Here, T is tension, m is the mass of the hanging object, a is the acceleration, r is the radius of the pulley, I is the moment of inertia of the pulley. I'm supposed to combine the two equations to eliminate T and solve for a. 3. The attempt at a solution OK, solve equation 1 for T. T = ma + mg Cool, now plug into equation 2. (ma+mg)r=I(-a/r) mr(a+g)=I(-a/r) a+g=I(-a/mr^2) 1+g/a=I/mr^2 g/a=-I/mr^2-1 a = -(gmr^2)/(I)-g I keep coming out with the same exact solution every time, but it is apparently wrong. Can someone tell me where I went wrong?