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At least on television, ski jumpers seem to fall great vertical distances before they hit the ground - at least a few dozen meters, though I couldn't find exact distances via a quick search. And yet they almost always land on their feet as if they just fell two or three meters. (Here's a whole lot of footage from the Vancouver Olympics if you need to refresh your memory.)

Without going into the level of equations (which I wouldn't understand), why are ski jumpers able to fall such great heights without seriously injuring themselves?

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The Eddie the Eagle Rule was instituted to prevent Olympic suicide. –  Glen The Udderboat Feb 10 '13 at 16:17

3 Answers 3

up vote 6 down vote accepted

This is related to the angle of the slope they are landing on. There is a good article that discusses the specific mechanics of the landing so I won't repeat it here. However, since there is a considerable amount of the momentum directed in the forward direction, the velocity vector associated with the skier is not pointed straight down. If you have a surface that is sufficiently parallel with the skier's velocity vector, they can land with very little force when they make contact.

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Upvotes for all of you, but I think this one does the best job of answering the question sufficiently within my capability of understanding. Thanks to you all. –  Garrett Albright Feb 16 '13 at 7:05

A main part is because they are landing on a slope. It means that for most, if not all, of the jump they are travelling parallel to the ground. The jump looks impressive because a) it is and b) the camera angles don't show this clearly.

This slope means that when the jumper lands they can carry on moving forwards with virtually the same velocity they had when they were in the air. The slope isn't constant, so if you don't jump far enough or jump too far the landing can be be dangerous.

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As @ChrisF correctly says, landing too far towards the end of the slope, hence towards the end where it becomes less steep and less parallel to the flight path of the jumper, would be very dangerous.

In ski jumping, every jump and slope is designed for a fixed jump length. This length is given by the K-Point which designates how far at most the contestants should jump. Up to this point, a safe landing can be achieved by any well-trained contestant. Landing beyond the K-point is dangerous. Or rather, it would be.

According to the rules, before the contest, the jury decides on the length of the inrun, taking into account the state of the jump, the weather and in particular the wind, thus making sure that the chance of contestants landing beyond the K-point is minimized.

Also, if one contestant reaches 95% of the jump length, the jury will interrupt the contest and decide whether the inrun should be shortened[1].

Note that there's quite a lot of additional rules about the equipment of the contestants, including details about the suit and the skis, which ensure that the jump widths in one particular contest tend to be somewhat predictable.

So, it's the rules that ensure that ski jumping on a carefully constructed jump is not suicidal. In fact, jumping on your self-built jump might be more dangerous than any jump you see on TV.

[1] Don't ask me what happens to the contestants that have performed their jumps up to that point in time.

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