A woman is holding an 8-lb weight in her hand with the entire arm held horizontally as shown in the fig- ure. A tensile force in the deltoid muscle prevents the arm from rotating about the shoulder joint O; this force acts at the 21" angle shown. Determine the Deltoid muscle force exerted by the deltoid muscle on the upper arm Fa at A and the x- and y-components of the force reac- tion at the shoulder joint O. The weight of the upper arm is Wy = 4.1 lb, the weight of the lower arm is 21" W. = 24 lb, and the weight of the hand is Wy = W 0.9 lb; all these weights act at the locations shown in the figure. 16.52 An. Fo - 160.2 1b. O, - 149.5 1b, 0. = -42.2 lb