# A Stiff-Legged Landing

1. Oct 26, 2009

### CaptFormal

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

2. Oct 26, 2009

### willem2

what is the average acceleration?

F=ma

3. Oct 26, 2009

### CaptFormal

I don't know. How would you go about solving for it?

4. Oct 26, 2009

### willem2

Average acceleration is $$\Delta v / \Delta t$$