75. what hanging mass must be placed on the cord to keep the pulley from rotating (see the following figure)? the mass on the frictionless plane is 5.0 kg. the inner radius of the pulley is 20 cm and the outer radius is 30 cm.figure shows the pulley in which a mass of 5 kg rests on an inclined plane at a 45 degree angle and acts as a counterweight to an object of the unknown mass that hangs in the air.