free fall elevators

[Cristatus]

me and my friend were at college in the lift, and the lift suddenly jerked up and down, a couple of times, as if it were going to free fall. once we got out, i asked him, what would you do if the lift did actually fall freely, and you were still inside the lift. he said the best thing to do would be to lay flat. does that really make sense?

 

[FrankSchwab]

You need to watch Mythbusters more often....

Anyway, if the elevator free-falls, you would be in a zero-gravity environment, as well as being pretty much completely disoriented. Your ability to change your position would, for all practical intents, be zero. But, ignoring the reality....

The elevator won't be completely in free-fall; there will be some air resistance slowing it down, as well as cables possibly unwinding off spools and guide wheels dragging. This means that the elevator will be falling slower than freshman physics (1 g in a vacuum) would dictate, but probably not significantly slower. Assuming the elevator fell 5 stories (16 meters for arguments sake), it would be travelling no more than 17 m/s (about 38 mph) when it hit in 1.8 seconds.

You can't jump upwards hard enough to save yourself - you'd have to launch yourself upwards at 17 m/s, which means you could do a standing high jump of 16 meters. You would ram yourself into the roof of the elevator as hard as if you had hit the ground.

Laying flat on the floor would probably minimize the damage you your body, but would probably still cause fatal brain damage, depending on how quickly the elevator decelerated.

My suggestion would be to let your friend lay down flat on the floor, and you lay down on top of him. Your body crushing his would reduce the deceleration you are subject to, possibly saving your life.

/frank

 

[unipidity]

Yes. But 17m/s I would have thought is easily survivable. Terminal velocity is over 50m/s, and there are recoded cases of people surviving terminal velicty falls from silly heights (thousands of feet, though it makes no difference), when they landed on sand or snow. I dont know how deformable or think the bottom bit of an elevator is, but if there is a 'crumple' zone of some kind, by design or accident, I reckon it would be survivable. Lying on top of a companion sounds like a great idea though.

 

[Chaotic42]

Maybe they should put large springs under the elevators to absorb the shock. When the spring is most compressed, a locking mechanism clamps over the elevator and keeps it from moving.

 

[Philippine Mango]

I've always thought of that when ever I go to my friend's house because they have a hydraulic elevator and has a tendancy to move up and down (scary). When the elevator starts acting funny I usually keep my hand on the red "stop" button hoping the breaks will work if it does fail.

 

[silverpig]

Laying flat is not a great idea. Basically you're pretty much screwed though. If you can, the best thing to do is to lean against the wall with your back to it and your feet slightly in front of you with your knees bent. Your legs will cushion your fall, provided you have the presence of mind and time to do something about your impending doom.

 

[joburnet]

The best thing to do in a situation like that is to follow these steps.

1. Stand with your legs about shoulder width apart and knees slightly bent to brace for impact.

2. Bend over putting your head between your knees

3. Kiss your ass goodbye

 

[dkozloski]

A company where I worked years ago was installing a hydraulic elevator. The first trip up, the platform stuck in the shaft at the second floor. The down button was pushed and the hydraulic ram retreated to the basement. The guy standing on the platform decided to jumped up and down to release the stuck platform thinking that the hydraulics had only retracted a short way. As his feet left the platform on the first jump the platform fell to the bottom with him just a little ways behind it. The platform hit bottom and rebounded from springs and met him coming down. He broke both ankles. Also FWIW, the flight deck elevator on an aircraft carrier moves so quickly that if you jump on to the platform after it starts down, you won't catch up to it until it stops.

 

[Jeffyboy]

take the stairs
you'll get more exercise

 

[Mik3y]

Originally posted by: Jeffyboy
take the stairs
you'll get more exercise

bingo

 

[mordantmonkey]

i thought elevators were required to have a braking mechanism at the basement level in case of an equipment failure.

 

[NewBlackDak]

Yeh, just like the asbestos ceiling and floor tiles should all be gone.

 

[DrPizza]

Your best bet for survival would be standing up... I'd guess you'd want your legs slightly bent and your muscles clenched as tightly as you can.. then, hopefully your legs would act as a crumple zone, allowing your vital organs and brain to decelerate at a rate they can survive.

Here's an idea to test my hypothesis though. I'll jump from 5 feet up and land on my legs. The person who think that lying flat is best can be raised 5 feet above the ground and dropped flat on his back. Then we go to 10 feet up, and so on until one of us gives up.

 

[jagec]

Originally posted by: mordantmonkey
i thought elevators were required to have a braking mechanism at the basement level in case of an equipment failure.

usually the braking mechanism is on the car itself, and there's also a spring at the bottom. However, in any decent high-rise, if the braking mechanism on the car fails, you're screwed.

 

[dkozloski]

The secret to the success of the Otis Elevator Company was the automatic braking system that catches the car with a ratchet mechanism if the cable or lifting equipment fails. There has never been a free fall of an Otis elevator and they've been in business over 150 years.

 

[mordantmonkey]

Originally posted by: DrPizza
Your best bet for survival would be standing up... I'd guess you'd want your legs slightly bent and your muscles clenched as tightly as you can.. then, hopefully your legs would act as a crumple zone, allowing your vital organs and brain to decelerate at a rate they can survive.

actually you can much better survive a force perpendicular to your spine... that's why seat belts work so well.

that's also one reason that in a crash landing they tell you to lean forward all the way, if you were sitting up straight you would crush you spine pretty easy. it's the downward motion not the forward motion that is so dangerous. I don't know that exact numbers but the spine handles FAR less compression force.

edit: of course i guess crushing your ankles and breaking your tibia(s) would probably absorb alot of shock too.

 

[onix]

Originally posted by: unipidity
Yes. But 17m/s I would have thought is easily survivable. Terminal velocity is over 50m/s, and there are recoded cases of people surviving terminal velicty falls from silly heights (thousands of feet, though it makes no difference), when they landed on sand or snow. I dont know how deformable or think the bottom bit of an elevator is, but if there is a 'crumple' zone of some kind, by design or accident, I reckon it would be survivable. Lying on top of a companion sounds like a great idea though.

Since we're being technical here, terminal velocity depends on the density, and outside surface shape. Note that the Space Shuttle gets pretty hot under orbit re-entry -- true this isn't exactly terminal velocity at fixed air pressure, but you get the drift.

 

[JonB]

Also FWIW, the flight deck elevator on an aircraft carrier moves so quickly that if you jump on to the platform after it starts down, you won't catch up to it until it stops.

I spent a lot of quality time on the USS Enterprise and just can't support this statement. Yes, it is fast, but nowhere near that fast. I suppose if it were 30% down when you jumped, you might not catch it before the bottom, but there is no good reason to put excessive G forces on airplane ordinance. It takes time to get a plane onto and off of the platform, so saving 3 seconds isn't of any value.

 

[RichPLS]

The elevators should be designed with a rubber o-ring type gasget so in free fall, the air pressure would keep it from attaining lethal speeds.

 

[Farmer]

All elevators should using have a solid fuel rocket on them, so that, in case of a cable failure, the passengers are rocketed into orbit.

 

[dethman]

Originally posted by: JonB

Also FWIW, the flight deck elevator on an aircraft carrier moves so quickly that if you jump on to the platform after it starts down, you won't catch up to it until it stops.

I spent a lot of quality time on the USS Enterprise and just can't support this statement. Yes, it is fast, but nowhere near that fast. I suppose if it were 30% down when you jumped, you might not catch it before the bottom, but there is no good reason to put excessive G forces on airplane ordinance. It takes time to get a plane onto and off of the platform, so saving 3 seconds isn't of any value.

for a second there i was thinking star trek.