Problem 14 When we turn on a computer our harddrive need to spin up from rest. Average platter (#1 in the picture) spin up time from rest to 7200rpm (revolution/minute) is 100 × 10-6s. For simplicity you may assume that harddrive platter is a solid cylin- der of mass 30g and radius of 12cm. You may ignore the hole in the middle. spindle magnetic platter actuator electronics (PCB) magnetic head actuator arm (a) Find the moments of inertia for the harddrive platter. (b) Find the average torque the spindle exert on the platter during spin up time.