Chapter 8, Problem 24P

When a person stands on tiptoe (a strenuous position), the position of the foot is as shown in Figure P8.24a. The total gravitational force on the body, ${\stackrel{\to }{\text{F}}}_{\text{g}}$, is supported by the force $\stackrel{\to }{\text{n}}$ exerted by the floor on the toes of one foot. A mechanical model of the situation is shown in Figure P8.24b, where $\stackrel{\to }{\text{T}}$ is the force exerted by the Achilles tendon on the foot and $\stackrel{\to }{\text{R}}$ is the force exerted by the tibia on the foot. Find the values of T, R, and θ when F_g = n = 700. N.

Figure P8.24