1. The problem statement, all variables and given/known data Consider a system of two masses joined by a massless string with the string passing over a massless frictionless pulley with a radius of 5.0 cm. The mass of the left is 9.00 kg and the mass on the right is 1.60 kg. Find the angular acceleration of the pulley when the masses are released from rest, and in which direction the pulley is spinning. (Find the magnitude of the angular acceleration.) 2. Relevant equations F=m*a torque = I*alpha (angular accerleation) T=m*g-m*a 3. The attempt at a solution I tried getting the two tensions. T1 = (9kg)(9.8m/s^2)-(9kg)a; T2 = (1.6kg)(9.8)+(1.6kg)a Then torque 1 - torque 2 = I*alpha, though the second part is 0 because the mass of the pulley is 0. So I end up with Tension 1 equals tension 2 (I divided out the radius). (9kg)(9.8m/s^2)-(9kg)a = (1.6kg)(9.8)+(1.6kg)a This gave me a = 9.8 m/s^2. I divided it by the radius, .05 meters, to get an angular acceleration of 196 radians/second. This answer is wrong however.