1. The problem statement, all variables and given/known data A block of mass M is on a frictionless table that has a hole a distance S from the block. The block is attached to a massless string that goes through the hole. A force F is applied to the string and the block is given an angular velocity w0 , with the hole as the origin, so that it goes in a circle of radius S. The force F is increased, starting at time t = 0, so that the distance between the block and the hole decreases according to S-c1t2 . Here c1 is a known, positive constant. Assuming the string stays straight and can only pull along its length, find the torque about the hole exerted by each force acting on the block and the angular acceleration of the block as a function of time. Here is the picture. 2. Relevant equations acceleration vector = [d2r/dt2 - rw2] ir + [2(dr/dt)(w) + r α] iθ 3. The attempt at a solution Looking at the system from the top, the torques are: TN = -mg(S-c1t2) iθ Tmg = mg(S-c1t2) iθ TF = 0 given that r = S-c1*t2 dr/dt=-2c1t d2r/dt2 = -2c1 Then using F=ma Fr = m[-2c1 - (S-c1t2)w02] Fθ = m[(S-c1t2)α - 4(c1t)(w02)] Assuming that the Fr and Fθ components are correct, I still don't know where to go, especially because it doesn't tell us about this force, which is not a constant. I am working out review problems for a test, so I know that the final answer is: α = (4S2w0c1t) / (S - c1t2)3 I am trying to understand how to get the solution, so I will be able to do similar problems on the test. Also, are the torques I wrote above correct?