Question

When jumping straight down, a person is advised to bend his knees upon landing to reduce the force of impact. Compare the impact force experienced by a 75-kg man when he jumped straight down when (a) he landed with stiff legs and it took 4.0x10 -4 s for him to stop and (b) he bent his knees and he stopped in 2 s. His speed just before contact with the ground is 7.5 m/s.

          When jumping straight down, a person is advised to bend his 
knees upon landing to reduce the force of impact. Compare 
the impact force experienced by a 75-kg man when he 
jumped straight down when (a) he landed with stiff legs and it 
took 4.0x10
-4 s for him to stop and (b) he bent his knees and he 
stopped in 2 s. His speed just before contact with the ground is 
7.5 m/s.

Added by Rui R.

Physics

John D. Cutnell, Kenneth W. Johnson 8th Edition

Chapter 7

Instant Answer

Solved by Expert Deepak Jangra

Step 1

We need to compare the impact force experienced by a person when landing with stiff legs versus bending knees. The key difference between the two scenarios is the time it takes for the person to stop after hitting the ground. Show more…

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When jumping straight down, a person is advised to bend his knees upon landing to reduce the force of impact. Compare the impact force experienced by a 75-kg man when he jumped straight down when (a) he landed with stiff legs and it took 4.0x10 -4 s for him to stop and (b) he bent his knees and he stopped in 2 s. His speed just before contact with the ground is 7.5 m/s.