When jumping straight down, you can be seriously injured if you land stiff-legged. One way to avoid injury is to bend your knees upon landing to reduce the force of the impact. A 80.6-kg man just before contact with the ground has a speed of 6.59 m/s. (a) In a stiff-legged landing he comes to a halt in 3.82 ms. Find the magnitude of the average net force that acts on him during this time. (b) When he bends his knees, he comes to a halt in 0.206 s. Find the magnitude of the average net force now.

2 answers

the man changed his velocity by 6.59 m/s in 3.92 ms, so his deceleration was

a = 6.59m/s / 0.00659s = 1000m/s^2

and, since F = ma, the force should now be obvious.
it is ...idk