When jumping straight down, you can be seriously injured if youland stiff-legged. One way to avoid injury is to bend your kneesupon landing to reduce the force of the impact. A 67.3-kg man justbefore contact with the ground has a speed of 3.81 m/s. (a) In astiff-legged landing he comes to a halt in 2.92 ms. Find themagnitude of the average net force that acts on him during thistime. (b) When he bends his knees, he comes to a halt in 0.255 s.Find the magnitude of the average net force now. (c) During thelanding, the force of the ground on the man points upward, whilethe force due to gravity points downward. The average net forceacting on the man includes both of these forces. Taking intoaccount the directions of the forces, find the magnitude of theforce applied by the ground on the man in part (b).
