Summing the forces on the block and the torques (about the axle) on the hub, we get two second-law equations (r is the radius of the hub, and I is the moment of inertia of the rotating system)...Summing the forces on the block and the torques (about the axle) on the hub, we get two second-law equations (r is the radius of the hub, and I is the moment of inertia of the rotating system): So all we need to do to compute the moment of inertia is measure the acceleration of the falling mass, as well as the amount of mass hanging on the string and the radius of the hub.
