Asolid disk of mass m and radius r is moving with a constant angular velocity of w when an external torque begins to slow the disk down. it goes through exactly x revolutions before coming to a stop. a. derive an expression for the net torque applied to the disk. express your answer in terms of the givern variables and fundamental universal constants b. if the force causing the torque had been applied at a ½ the distance, by what factor would the total revolutions completed before stopping change?