1. The problem statement, all variables and given/known data "A drum of 60-mm radius is attached to a disk of 120-mm radius. The disk and drum have a total mass of 6 kg and a combined radius of gyration of 90 mm. A cord is attached as shown and pulled with a force P of magnitude 20 N. The disk rolls without sliding. Determine the minimum value of the coefficient of static friction compatible with this motion." I have attached the image below 2. Relevant equations T = Iα 3. The attempt at a solution Known forces: W = (6 kg)(9.81 N/kg) = 58.86 N, downwards, at G First, because the system is not accelerating in the y direction we know that: N = W - P = 58.86 - 20 = 38.86 N Friction then will equal: f = 38.86μ Moment of Inertia: I = (6 kg)(0.09 m)^2 = 0.0486 kg*m^2 So, now the sum of all torques: T = -(0.12 m)(38.86μ) = (0.0486 kg*m^2)α I'll need angular acceleration of the middle disc. What would I need to do to find that? Also, I'm assuming there has to be another horizontal force (presumably at G), how would that factor in?