Shown below is the horizontal ground reaction force (GRF) for a person with abnormal gait. In this figure, positive forces are directed from behind toward the front of the body (i.e., in the direction of progression). Suppose we can express the horizontal GRF as a function of time, Fh(t). (a, 10 points) (b, 5 points) GRF as a % of Body Weight 20- -20 foot contact Fn(t) toe off time Derive an expression for the horizontal kinetic energy of the mass center. Define all terms in your expression. Put a box around your answer. At what point in the gait cycle does the forward speed reach a minimum? You can mark this on the diagram above. Why does the minimum occur at this point?