Let me briefly respond to an earlier post by emtnate regarding Albrecht's fall:
emtnate said:
"Also to the people stating various speeds of crashed. The impact of the skier to the ground, especially in Albrecht's case really isn't that fast. Gravity acts on all objects the same, like RR said, 9.8 m/sec(squared) which is about 32 ft per second or 21 mph. Not that fast compared to his ground level speed of 80 mph, but the impact on his head and back is still significant. In EMS in the US it is generally accepted that falls from a height greater than 15 feet need to be treated in a trauma center. From the video, I'd estimate his vertical fall to be between 30-40 ft from the height he hit the jump until he landed."
my comment:
In a really high speed fall, the issue is not the gravitational acceleration right before the crash (not off a jump, going 65 mph, falling from a tuck is only a short distance to the ground, but I don't recommend it.) It's that if you hook an edge, a small fraction (but still painfully substantial portion) of that forward energy is converted into rotational energy, as your legs slow, your upper body essentially pivots, slamming into the ground. And the amount of kinetic energy involved in a crash as you increase speeds is exponential. (the kinetic energy of a body in motion is mass times the square of speed) so a skier at 60 mph is managing not twice the kinetic energy of a skier going 30 mph, but rather four times (and 16 times the energy of a skier going 15 mph.) That is the kinetic energy involved in a crash, which you want dissipated over a long distance, not all at once.
(Hit a tree square and stop, even at recreational skier speeds, and it's a LIBE--life insurance benefit event; catch an edge and slam forward into the ground at even higher speeds, bouncing and sliding for another 20 plus feet, and it's merely a MIBE--medical insurance benefit event.)
For an example, let's look at this less than eleven second clip of Daron Rahlves' crash in the Adelboden GS a few years ago:
http://www.youtube.com/watch?v=0hax4ufjqOs
1. This is only GS speeds, something like 45 mph.
2. Look how he gets launched end over end as just a small portion of the forward energy causes him to somersault through the air.
3. Note the foam barrier at the end, which does not stop Daron suddenly (which would have been at least an MIBE) but merely slows him and saves the crowd. By design.
Daron was sore, but fine, and in the next race on the WC circuit a week or two later, took a silver medal (in SG, IIRC.)
SfDean.