Calculate the impulse experienced when a 66 kg person lands on firm ground after jumping from a height of 2.8m. Estimate the average force exerted on the person's feet by the ground if the landing is stiff-legged. With stiff legs, assume the body moves 2.0 cm during impact. [Hint: The average net force on her which is related to impulse, is the vector sum of gravity and the force exerted by the ground.] Estimate the average force exerted on the person's feet by the ground if the landing is with bent legs. When the legs are bent, assume the body moves about 40cm during impact.