If you wear kneepads when skating, after a fall to your knees it will take 3 times as long for them to come to a rest. How does this affect the change in momentum of your knees during the fall? A. The change in momentum is the same with or without the kneepads B. The change in momentum decreases by a factor of 9 C. The change in momentum decreases by a factor of 3 D. The change in momentum increases by a factor of 3

Question

Physics

Emilee Terrell

14 December, 07:06

If you wear kneepads when skating, after a fall to your knees it will take 3 times as long for them to come to a rest. How does this affect the change in momentum of your knees during the fall? A. The change in momentum is the same with or without the kneepads B. The change in momentum decreases by a factor of 9 C. The change in momentum decreases by a factor of 3 D. The change in momentum increases by a factor of 3

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Ruben Butler · Answer 1

When you fall, you arrive at the floor with some momentum. It makes

no difference what stops your fall, or how long it takes to stop your fall.

It still has to absorb the same amount of momentum, somehow. As long

as your body still has any downward momentum, you're still falling.

The total change in momentum can also be viewed as some amount

of 'impulse' ... the product of force and the time that the force persists.

The knee pads absorb your momentum slower than the bare floor does,

and since the process of changing your momentum lasts longer, the

corresponding force against your knees is smaller with the pads.