Answer to Question #152458 in Physics for peter mulenga

Question

To immobilize a fractured femur (the thigh bone), doctors often utilize the Russell traction
system illustrated in the figure below. Notice that one force is applied directly to the knee,
F1, while two other forces, F2 and F3, are applied to the foot. The latter two forces combine
to give a force F2 + F3 that is transmitted through the lower leg to the knee. The result is that
the knee experiences the total force Ftotal = F1 + F2 + F3. The goal of this traction system is to
have Ftotal directly in line with the fractured femur, at an angle of 20.0° above the horizontal.
Find (a) the angle

Answer 1

$$F_{1x }= -41.65\cos(ϴ-20)\\ F_{1y} = 41.65\sin(ϴ-20)\\ F_{2x } = -41.65 N\\ F_{2y } = 0 N\\ F_{3x } = -41.65\cos(40)\\ F_{3y } = -41.65\sin(40)\\$$

$$41.65\sin(ϴ-20) = 41.65\sin(40) \\ ϴ = 60\degree$$