Problem 5: An Olympic gymnast is stationary in the \"iron cross\" position. The weight of his left and right arm is the same, each being 8 lb. The weight of his body, not including his arms, is 144 lb. The distances are a = b = 9 in and c = 13 in. Treat his shoulder S as a xed support. Determine the magnitude of the reactions at his shoulder. 81b