O corresponds to the center of rotation of the hip joint. A is the connection point of the hip abductor muscle with the femur; point B is the center of gravity of the leg; and C is the point of application of the ground reactive force. The distances between point A and points O, B, and C are: a = 8.6 cm, b = 34.3 cm, and c = 89.4 cm. The angles formed by the femoral neck and the longitudinal axis of the femur with respect to the horizontal are alpha = 43° and beta = 79°, respectively. Further
Consider a person who momentarily puts all of their body weight on one leg when walking or running. The forces acting on the leg and the corresponding biomechanical model of the system are shown in Fig.- Prob. 10(a) and (b). Point O corresponds to the center of rotation of the hip joint. A is the connection point of the hip abductor muscle with the femur; point B is the center of gravity of the leg; and C is the point of application of the ground reactive force. The distances between point A and points O, B, and C are: a = 8.6 cm, b = 34.3 cm, and c = 89.4 cm. The angles formed by the femoral neck and the longitudinal axis of the femur with respect to the horizontal are alpha = 43° and beta = 79°, respectively. Furthermore, for this position of the person standing on one leg, it has been estimated that the magnitude of the force exerted by the hip abductor muscle is FM = 2062.6 N and its line of action forms an angle of theta = 69° with respect to the horizontal. If the magnitude of the gravitational force acting on the leg is W1 = 125 N, determine:
(a) The total weight W of the person;
(b) the magnitude of the reaction force FJ acting at the hip joint;
(c) an angle gamma that the line of action of the joint reaction force makes with the horizontal.
Fig.-Prob. 10: Biomechanical Model of a Person Standing on One Leg: (fig a) Forces acting on the right leg carrying the entire weight of the body. (fig b) D-C-L of the leg indicating the forces and geometric parameters
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