AP Physics - Equilibrium

posted by .

The Achilles tendon is attached to the rear of the foot as shown in the figure below. When a person elevates himself just barely off the floor on the ball of one foot, estimate the tension Ft in the Achilles tendon (pulling upward) and the (downward) force Fb exerted by the lower leg bone on the foot. Assume the person has a mass of 72 kg and D is twice as long as d.

Here's the figure:

img687.imageshack.us/img687/663/img3552n.jpg

I have no idea where to start.

  • AP Physics - Equilibrium -

    Well, sum moments about any point. I will do at the ball of the foot.

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

    But weight of the person is bearing down on the leg bone (assuming two legs, one-half the weight). so Fb=72/2 g

    Ft=2/3 72/2 g or about 235N

  • AP Physics - Equilibrium -

    1231N

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. College Physics

    As part of an exercise program, a 75 kg person does toe raises in which he raises his entire body weight on the ball of one foot. The Achilles tendon pulls straight upward on the heel bone of his foot. This tendon is 25 cm long and …
  2. physics

    When a person stands on tiptoe (a strenuous position), the position of the foot is as shown in Figure P8.16a. The total gravitational force on the body, Fg, is supported by the force n exerted by the floor on the toes of one foot. …
  3. Physics

    If a 60 kg person stands on a low wall with her full weight on the ball of one foot and the heel free to move, the stretch of the Achilles tendon will cause her center of gravity to lower by about 2.5 mm. What is the spring constant …
  4. physics

    When you stand on your tiptoes, your feet pivot about your ankle. As shown in the figure, the forces on your foot are an upward force on your toes from the floor, a downward force on your ankle from the lower leg bone, and an upward …
  5. physics

    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 80kg and D is twice as long as d.Find the …
  6. Physics

    The Achilles tendon is attached to the rear of the foot. Assume that a person has a mass of 53 kg and that D is twice as long as d. When a person elevates himself just barely off the floor on the "ball of one foot," estimate the tension …
  7. Physics

    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 65kg and D is twice as long as d. Find …
  8. Physics

    Human feet and legs store elastic energy when walking or running. They are not nearly as efficient at doing so as kangaroo legs, but the effect is significant nonetheless. If not for the storage of elastic energy, a 70.0-kg man running …
  9. Physics

    A 83.2-kg man stands on his toes by exerting an upward force through the Achilles tendon, as in the figure below. What is the force in the Achilles tendon if he stands on one foot?
  10. Physics

    The Achilles tendon is attached to the rear of the foot as shown in Tap image to zoom . A person elevates himself just barely off the floor on the "ball of one foot." Assume the person has a mass of 61 kg and D is twice as long as …

More Similar Questions