A patient undergoing physiotherapy is required to perform an exercise in which she supports a 65.3 N weight by pulling on a rope at an angle of 50 to the vertical, as shown in the diagram below. Her arm, of weight 37.5 N, is horizontal and at rest. The centre of mass of the arm 1s 27.3 cm from the shoulder joint, the muscle is attached 7.5 m from the joint and acts at an angle of 20. Apply the conditions for static equilibrium about the joint to determine the magnitude of M, the force of the muscle on the arm. The magnitude of force M 1s (5) e _ 59.3.m ST LIS