A subject with height 1.68m and weight of 700N is climbing a staircase, the anthropometric ratios relevant to the modelling are AB=0.12H, AC=0.24H, dy=0.03H, CD=0.29H.The height of the staircase riser is 33cm. compute the erector muscle force,Fm, the reactions at the knee and the foot on the upper staircase.