# When you fall from a height, a small roof for example, what softens your fall more? A matress lying on the floor or one up in the air (different possibilities, 4’/10cm, 7″/2m, at jump level) i.e. held up by two people?

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When you fall from a height, a small roof for example, what softens your fall more? A matress lying on the floor or one up in the air (different possibilities, 4’/10cm, 7″/2m, at jump level) i.e. held up by two people?

In: Physics

Almost certainly the mattress held up by two people.

First, you have a shorter distance to fall, so less time to accelerate. So the force when you hit will be smaller.

Second, two people holding up the mattress at the end will permit it to bend in the middle as well as cushion the fall. This gives more distance over which your fall can be slowed – and the force of impact is based on how quickly you’re forced to decelerate.

One held up will soften the fall more. “Softening the fall” means reducing the acceleration you experience when you hit the ground. Acceleration is change in velocity / time. The mattress being held up will reduce this in two ways. One, decreasing the velocity: you will be moving more slowly when you hit it, since you fell for a shorter distance. Two, increasing the time: you will be slowing down as the people absorb the force with their arms and lower the mattress AND as you compress the mattress, instead of just compressing the mattress.

What kills you is not the fall from height but the sudden stop at the end. What you want to do is to extend that stop to be a longer more gradual slowdown. So the sooner you start slowing down the more softened the fall is. However there needs to actually be something slowing you down. Having a matress under you falling with you is of no help. However if there are people trying to hold the matress up in the air they will slow you down all the way to the ground so you hit the ground very soft if you hit the ground at all.