1. The following is one frame of data collected during a biomechanical gait analysis. You must show all your math work to receive credit.

(a) Use this information to calculate the net joint forces (X and Z) and net muscle moment at the knee. (0.8 points)

(b) What is the main muscle group acting to produce this moment? (0.2 points)

Knee (1. 32, 0.52) GRF X = -78.5N GRF Y = 581.7N GRF coordinates (1.52, 0.00) Foot COM coordinates (1.4, 0.06) Ankle coordinates (1.30, 0.09) Subject mass = 56.7 kg Foot length = 0.25 m (1.30, 0.09) Ankle 14.51 rad/s2 -5.57 m/s2 Toe -0.98 m/s2 GRF X and Y (red vectors)