Chapter 12, Problem 28P

Figure 12.20 shows the fool and lower leg of a person standing on the ball of one foot. Three forces act to maintain this equilibrium: the tension force $\stackrel{\to }{T}$ in the Achilles tendon, the contact force $\stackrel{\to }{F_c}$ at the ankle joint, and the normal force $\stackrel{\to }{n}$ that supports the person’s 697-N weight. The application points for these forces are shown in Fig. 12.20. The person’s center of gravity is directly above the contact point with the ground, and you can treat the mass of the foot itself as being negligible. Find the magnitudes of (a) the tension in the Achilles tendon and (b) the contact force at the ankle joint.

FIGURE 12.20 Problem 28