Halliday, Resnick & Walker — Equilibrium and Elasticity: Problem Problem_82

Standing on tiptoes. In Fig. 12.69, a person with weight \(mg = 700 \text{ N}\) stands on “tiptoes” (actually, the ball of the forefoot) with the weight evenly distributed on each foot and with the plane of each foot at angle \(\theta = 20^\circ\) with the floor. The support is an upward force at distance \(d_f = 0.18 \text{ m}\) from the ankle about which the foot can rotate. At distance \(d_b = 0.070 \text{ m}\) from the ankle, the Achilles tendon (connecting the heel to the calf muscle) pulls on the heel with force \(\vec{T}\) at an angle of \(\phi = 5.0^\circ\) from a perpendicular to the plane of the foot. What is the magnitude of \(\vec{T}\)?