Question

An 80 kg individual is in a seated position on a machine that tests knee extension strength. The calf length is 0.440 m, calf/foot mass is 5.8% of the body mass, calf/foot center of mass is 53% of the calf length from the knee joint, and calf/foot moment of inertia about the knee joint is 0.350 kgm2. The quadriceps moment arm is 0.040 m. The machine’s padding contacts the calf at a constant moment arm (does not change with knee angle) of 0.420 m from the knee joint.

9. At zero machine resistance, the knee joint angle is held at a constant 0 (full extension) with the calf in a horizontal position. How much quadriceps muscle force is being generated? A. 27 N B. 57 N C. 265 N D. 1138 N

10. Still at zero machine resistance, the knee joint angle is held at a constant 58 below the horizontal (knee flexion). How much quadriceps muscle force is being generated? A. 14 N B. 141 N C. 265 N D. 603 N

11. After setting the machine resistance to 230 N, the knee joint angle is held at a constant 58 below the horizontal. How much quadriceps muscle force is being generated? A. 151 N B. 2415 N C. 2556 N D. 5891 N

12. With a machine resistance of 230 N, the knee joint angle is 58 below the horizontal and has an angular acceleration of 17 rad/s2. How much quadriceps muscle force is being generated? A. 2564 N B. 2704 N C. 2829 N D. 2980 N

show work please

Answer 1