The triple jump is a track-and-field event in which the athlete gets a running start and tries to leap as far as he can with a hop, step, and jump. Shown in the figure is the initial hop of the athlete. Assuming that he approaches the takeoff line from the let with a horizontal velocity of 10 m/s, remains in contact with the ground 0.18 s, and takes off at 50 degree angle with a velocity of 12 m/s, determine the vertical component of the average impulse force exerted by the ground on his foot. Give your answer in terms of the weight W of the athlete.