http://www.straightdope.com/classics/a1_205a.html
Actually Cecil, there is a way to save yourself in a falling elevator. You should bend your knees, stick to the wall, and hold on to the bar on the side of the elevator. I saw this on worst case scenario. 
Did they explain how this would work? If the elevator is free-falling at 9.8m/s[sup]2[/sup], so are you, no matter what you are holding onto. Bending your knees isn’t going to absorb that much energy. If two people fall 6 stories out in the street, I don’t see how the guy with bent legs is going to do much better than the one with locked joints.
Remember, people have survived falls from airplanes before. I can see the OP’s point - if there’s a bar on the side of the elevator you can grab onto and pull yourself against the wall, then you have the strength from your arms, as well as the friction from the wall, preventing you from pancaking in the floor on impact. That’s an improvement overv just depending on your legs alone.
Granted, it’s not a much of an improvement, but it’s better than standing there with a dumb look on your face.
But surely not as good as lying on the floor on your back?
How far is this elevator falling exactly?
All the way to the ground, I guess.
… which might be a tricky manoeuvre in a free falling elevator.
I guess the idea is that laying on your back would spread out the force of the landing across the greatest surface area, but I don’t think that’d really help. That position would probably leave you most vulnerable to being impaled, and your heart, lungs and head would all be closer to the point of impact.
I don’t see your point. When you stand, your legs would act as shock absorbers on impact. By bracing yourself against the bar and the side of the elevator, you’re using your arms as shock absorbers, too. The net effect would be 1. Your arms and legs would be the first part of your body to bear the brunt of the impact. They would all immediately break, but the amount energy required to break them would be subtracted from the total amount of downward force you would currently be experiencing. 2. the trauma to your trunk and head might be reduced a tiny amount, possibly (but unlikely) enough to keep you alive.
If, on the other hand, you lie on the floor, then your spine becomes the first part of your body to bear the brunt of the impact, and would shatter instantly. That would pretty much gaurentee instant death. Or is that what you were aiming for?
This experiment was performed on the Discovery Channel’s Myth Busters episode called ‘Elevator of Death’.
The elevator fell (IIRC) 5 floors. The results indicated that IF a person could time the jump correctly, the necessary vertically applied force would result in the human head being driven into the roof of the elevator with a force that would instantly crush the scull.
In short, it can’t be done.
Ah, Bill Cosby figured that out years ago
He had a bit where he described all the ways he’d try and save himself in life-threatening situations.
“Now it might not work. Might not work at all. They may find 8 bodies all crumpled up at the bottom and one head through the top. But the will say…. man, he sure did try.”
Lying on the floor on your back is the worst thing you could possibly do. What kills you is the deceleration. You want to make your deceleration as small as possible, which means you want to spread it out over the greatest distance possible. If you’re lying on your back, then your deceleration distance is the amount by which your body can compress from front to back, a matter of a few centimeters at most. If you’re standing, on the other hand, then your deceleration distance is at least the length of your legs, and (if you manage to fall over at just the right point) potentially your entire height. I estimate that you could survive a fall from a thousand times higher, landing on your feet than rather than on your back.
Has this scenario ever actually happened, that a modern elevator free falls to the bottom? I’m often reminded when I get on an elevator that falling is what people tend to worry about, but the actual risks are much different and much greater. There was that young doctor a couple of years ago in Houston who stuck his head through the closing doors, which closed on him with his head through the doors, then the elevator started moving and decapitated him. Now that’s something to worry about!
Bill Nye the Science Guy did an experiment with a miniature elevator, and an egg on a spring. The egg was smashed. Basically, he explained, you have x amount of energy built up in the fall. You’d have to expend about that much energy by jumping up to survive the fall. Of course, your 30 meters of energy expenditure must be contained within a two-meter high box. IOW, if you were to jump with the same (or nearly the same) force, you’d just smash on the ceiling.
More that your body would not be impacting on the floor, being already there. Whatever the floor itself impacts on would have some of its energy absorbed by coming through the floor before it gets to you, presumably reducing damage done to you.
The deceleration is pretty much the same no matter what you do, I’m just trying to amelioriate its effects.
Estimate based on what? My estimate is it will make essentially no difference whatsoever.
Falling the height of your legs or body has no effect on your deceleration, that does not begin until you hit the floor (reduced by whatever upward force you can exert with your legs, which I contend is negligible in comparison to the other forces involved). It certainly could not reduce your deceleration by 99.9%
The MythBusters episode pretty well confirmed what a little logical thought would suggest (as already noted by QuickSilver): that to avoid injury, you would have to jump up at more or less the same speed as the elevator is going, which is (a) impossible, and (b) would smash your skull against the overhead.
BUT, I gotta say that watching the elevator drop those nine floors was one of the most terrifying sights I have EVER seen. In the movies they always show falling elevators in slow motion. Not MythBusters! They had removed the doors from each floor, to reduce any air-cushioning effect, and on each floor they had a camera mounted. WHOOOMMMPPPP!!!
You’re not falling the height of your legs or body, since you’re already on the floor. And ultimately, your body is going to be exerting high forces one way or another; what makes you say that your legs would be less capable of this than any other part of the body?
Incidentally, I didn’t say that your legs could reduce your deceleration by 99.9%. I said that the height you could fall from would be 1000 times greater. The two are not equivalent.
What I’m trying to say is, the only difference in the force your body experiences between standing and lying on your back is what counter-force you can exert with your legs (and I suppose arms, if you have something to hang from, but that is limited by the grip strength of your fingers and can be ignored I think). I contend this force is negligible in the circumstances although I can’t immediately see how to calculate this.
Now you may have something in the thought that you will concentrate more of the damage on your legs and pelvis and less in your more vital bits, but you may also find that your foot and leg bones get driven up … well, let’s leave it at that.
I just think that by lying on the floor (which you would have to do before the lift reaches terminal velocity) you reduce the amount of energy that impacts your body, because the floor will not smack you in the back, but whatever is underneath it will have to destroy floor to get to you, which will reduce that energy it has to expend in damaging you. The damage caused by deceleration will be the same, of course.
I’ll say they are not. g is 9.8m/s/s = 30ft/s/s. Cecil says terminal velocity is 100 ft/sec so it takes you just over three seconds to reach that speed in which time you have covered say 200 feet (30+60+90+ a bit). So you are saying you can fall 200 feet, impact at terminal velocity, and by using your method only suffer the damage you would from a fall of 200/1000 feet or 2.4 inches, that is none at all.
What if the elevator fell from the second floor only?