How would I find the acceleration of the above spindles (both left and right instances)? The spindles are composed of two disks with a cylindrical solid axle. The left spindle is unwinding the string as it rolls and the right spindle is winding the string as it rolls. Static friction is present and the spindle rolls without slipping. Any help would be greatly appreciated. I know that the applied force P minus the force of friction equals the mass times acceleration. I can't seem to figure out how to find the force of friction, with which it would be relatively easy to solve the problem.