The Achilles tendon is attached to the rear of the foot as shown in (Figure 1) .

Question

The Achilles tendon is attached to the rear of the foot as shown in (Figure 1) . A person elevates himself just barely off the floor on the "ball of one foot." Assume the person has a mass of 81 kg and D is twice as long as d

Part A

Find the tension FT in the Achilles tendon (pulling upward).

Express your answer to two significant figures and include the appropriate units.

Part B

Find the (downward) force FB exerted by the lower leg bone on the foot.

Express your answer to two significant figures and include the appropriate units.

Explanation / Answer

since the system is in equilibrium net torque about point of contact = 0

torque about point of contact = Fb * D - Ft * (d + D)

Fb * D - Ft * (d + D) = 0

D = 2d

Fb * 2d - Ft * (d + 2d) = 0

Fb * 2d = Ft * 3d

Fb * 2 = Ft * 3

torque about Fb = 0

torque about Fb = Ft * d - 81 * 9.8 * D

Ft * d - 81 * 9.8 * D = 0

Ft * d = 81 * 9.8 * 2d

Ft = 81 * 9.8 * 2

Ft = 1587.6 N

Fb * 2 = Ft * 3

Fb * 2 = 1587.6 * 3

Fb = 2381.4 N

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.