Question

Perform a dynamic analysis for a knee extension movement. The knee extensors insert on the tibia at an angle θ = 30°and at a distance d = 5.2 cm from the axis of rotation of the knee. The combined weight of lower leg and foot is Fwt = 48 N and its center of mass is r = 27 cm away from the knee joint axis. The joint angle with respect to the right horizontal is λ = 110° (Note: this is not the angle between thigh and lower leg). The angular acceleration of lower leg / foot segment has been measured to be α = +15 rad/s2 (counter-clockwise). The horizontal acceleration is computed to be ax = +0.25 m/s2, while the vertical acceleration is ay = + 0.15 m/s2.

Compute the following:

1. a) The rotational inertia of the limb.

2. b) The gravitational torque due to the weight of the leg/foot (Tg).

3. c) The underlying knee muscle torque (Tm).

4. d) The associated muscle force (Fm) that gave rise to Tm.

(2 pts.) (2 pts.) (2 pts.) (2 pts.)

Answer 1