To immobilize a fractured femur (the thigh bone), doctors often utilize the Russell traction system illustrated in

Question:

To immobilize a fractured femur (the thigh bone), doctors often utilize the Russell traction system illustrated in FIGURE 6-51. Notice that one force is applied directly to the knee, F(vector)₁, while two other forces, F(vector)₂and F(vector)₃, are applied to the foot. The latter two forces combine to give a force F(vector)₂+ F(vector)₃that is transmitted through the lower leg to the knee. The result is that the knee experiences the total force F(vector) total = F(vector)₁+ F(vector)₂+ F(vector)₃. The goal of this traction system is to have F(vector) total directly in line with the fractured femur, at an angle of 20.0° above the horizontal. Find

(a) The angle u required to produce this alignment of F(vector) total

(b) The magnitude of the force, F(vector) total, that is applied to the femur in this case. (Assume the pulleys are ideal.)

Fractured femu: 20.0 20.0% 20.0° 4.25 kg