Question

How much force must the quadriceps (moment arm of 4.5 cm) exert to maintain the lower leg at 59о from full extension? The combined weight of the lower leg is 60 N, with a center of gravity 30 cm from the axis.

Answer 1

To maintain the lower leg at an angle of 59 degrees from full extension, the quadriceps must exert a force of 400 N.

Step-by-step explanation:

To find the force exerted by the quadriceps to maintain the lower leg at an angle of 59 degrees from full extension, we can consider the torque equation. Torque is equal to the force multiplied by the moment arm. In this case, the torque required to maintain the leg angle can be equated to the torque due to the weight of the lower leg. Therefore, we can set up the equation:

Torque due to quadriceps = Torque due to weight of lower leg

(Force of quadriceps) * (moment arm of quadriceps) = (weight of lower leg) * (distance from axis to center of gravity of lower leg)

Plugging in the given values:

(Force of quadriceps) * (4.5 cm) = (60 N) * (30 cm)

Simplifying the equation and solving for the force of the quadriceps gives:

Force of quadriceps = (60 N * 30 cm) / (4.5 cm)

Force of quadriceps = 400 N