Hipx Hiру Kneex Kneey Anklex Ankley Frame Number 20 21 22 102.3 114.7 126.8 138.9 150.8 847.8 850.3 852.7 855.1 857.3 252.5 258.3 263.7 500.2 500.1 500.0 499.8 499.7 237.7 238.5 239.1 239.7 240.2 112.6 112.8 112.9 113.1 113.2 268.8 23 24 273.7 Equation Sheet Central Difference Method Vi = (Xi+1 - Xi-1)/2At ai = (Vi+l - Vi-1)/2At Use the first central difference method to calculate the thigh angular velocity in frame 21 and frame 23.