1. The problem statement, all variables and given/known data 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 72.6 kg man just before contact with the ground has a speed of 6.35 m/s. In a stiff-legged landing he comes to a halt in 2.19 ms. Calculate the average net force that acts on him during this time. 2. Relevant equations 3. The attempt at a solution I don't even know how to start this one. Please help.