physics-torque

posted by .

A person is doing leg lifts with 3.0-kg ankle weights. She is sitting in a chair with her legs bent at a right angle initially. The quadriceps muscles are attached to the patella via a tendon; the patella is connected to the tibia by the patellar tendon, which attaches to bone 10.0 cm below the knee joint. Assume that the tendon pulls at an angle of 20.0 with respect to the lower leg, regardless of the position of the lower leg. The lower leg has a mass of 5.0 kg and its centre of gravity is 22 cm below the knee. The ankle weight is 41 cm from the knee. If the person lifts one leg, find the force exerted by the patellar tendon to hold the leg at an angle of 90.0 with respect to the vertical (i.e. to hold the leg horizontal).

I don't know how to start this question, would I use torque=rFsinTHETA? then rearrange to get F? I'm not sure how to find the torque though.

How do I start this question?

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. ateletes

    to make your legs strong what should we do?
  2. Physics please help!!

    A 73.5 kg person sits on a 3.20 kg chair. Each leg of the chair makes contact with the floor in a circle that is 1.74 cm in diameter. Calculate the pressure exerted on the floor by each leg of the chair, assuming the weight is evenly …
  3. physics

    A 70 kg person sits on a 3.6 kg chair. Each leg of the chair makes contact with the floor in a circle that is 1.5 cm in diameter. Find the pressure exerted on the floor by each leg of the chair, assuming the weight is evenly distributed.
  4. physics

    A person is sitting with one leg outstretched, so that it makes an angle of = 39.9o with the horizontal. The weight of the leg below the knee is 34.7 N with the center of gravity located below the knee joint. The leg is being held …
  5. physics

    The figure is taken from a paper (Am J Sports Med 2004 32: 477) on injuries to the anterior cruciate ligament due to forces applied by the patella tendon. Take a particular case where the attachment force on the tibia is 5610N when …
  6. 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 …
  7. physics 1

    A person is sitting with one leg outstretched and stationary, so that it makes an angle of 30.0° with the horizontal, as the drawing indicates. The weight of the leg below the knee is 50.5 N, with the center of gravity located below …
  8. 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 …
  9. physics

    The large quadriceps muscle in the upper leg terminates at its lower end in a tendon attached to the upper end of the tibia (see figure (a)). The forces on the lower leg when the leg is extended are modeled as in figure (b), where …
  10. physics

    The large quadriceps muscle in the upper leg terminates at its lower end in a tendon attached to the upper end of the tibia (see figure (a)). The forces on the lower leg when the leg is extended are modeled as in figure (b), where …

More Similar Questions