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Q & A: Falling Overpass

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Most recent answer: 10/22/2007
Q:
If you fell from 10 feet in the air you would get hurt because you collided with the ground. Tonight before the physics review with Mats I was walking on the over pass at the University Inn to my truck. My friend was like it would hurt if the overpass fell with us in it. Then I thought would it. If you were laying on the floor of the overpass and you did not rise off the floor, say you held yourself to the floor and the overpass fell, what would happen to you.
- dave stein (age v)
UofI
A:
Dave,

The thing that hurts you when you hit the ground (i.e. breaks bones etc) is the force that acts on you as you stop. The average force is the change of your momentum divided by the length of the time interval during which you stop. Both of these quantities would be about the same whether you fell off the bridge onto the ground, or whether you were laying down on something that fell the same distance and hit the ground. In other words, since the change in momentum would be the same, and the time to stop would be about the same, the average force acting on you would be about the same, so you would get hurt about the same.

Mats

(published on 10/22/2007)

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