Cable that holds the elevator got disconnected

[AnthreX]

say u r in a elevator, and suddenly the cable that holds the elevator got disconnected and u r falling to the ground while standing,and dropping really fast from 15th floor. you would die right ?

this is the question.. just before the elevator crashes on the surface
what if you jump ? would you get hurt ?

 

[Michael D. Sewell]

That would be an understatement; unless you can jump 60 miles per hour(at the right moment). You could scream for approximately 3 seconds or so. It probably wouldn't do any good, but you'd have nothing better to do anyway.

 

[LURCH]

Right idea, but human legs can't generate nearly enough power to keep you alive. However, you would hit the ground going slower than if you had not jumped; just not "slower enough".

 

[UltraPi1]

There is a possibility that the elevator could slow enough as it got closer to ground zero. This would depend of how quickly the air beneath it could escape. You could conceivably walk away from this kind of scenerio. The elevator would reach terminal velocity rather quickly. As it dropped the pressure beneath it would increase as it got closer to ground zero. Again this is entirely dependent on how quickly the air beneath the elevator can escape. Under the right conditions it could be like landing on a big pillow.

 

[Michael D. Sewell]

Interesting idea. I wouldn't recommend that you demonstrate it without changing the current design that is commonly used.

 

[Gara]

it is possible, but if the lift is falling at 60 mph, you then have to jump up at 60 mph. (like that other guy said)

but also, you'd proberly then smash your head on the roof.

 

[Michael D. Sewell]

It just goes to show you; if it's not one thing, it's another. I've spent a lot of years skydiving. Most people seem to prefer screaming; I certainly do. -Mike

 

[pallidin]

Next time you see me in an elevator with a matress, I guess you'll know why... if the cable snaps, maybe I will quickly lay spread eagle on the matress.

 

[UltraPi1]

I'm not sure I have ever read an article about an elevator cable snapping, and other safety features failing also, where the elevator actually does a full drop. The safety features must be pretty failsafe.
Back to the original question - Would you die?
I would much rather fall 15 stories in an elevator than a full gainer to street pavement. Would you die though in an elevator? Parameters would have to be set to answer that question. How big is the elevator? How much does it weigh? How well sealed is the shaft? How much space is there between the elevator exterior to the shaft walls? If you poop in your pants and have a heart attack - Does that count as an elevator fatality?

 

[Evo]

I was in an elevator "crash". They never would tell me exactly what the cause was.

When I stepped into the elevator, there was a muffled "explosion", the elevator started dropping and then the saftey mechanism must've kicked in which caused the elevater to stop with such a violent jolt that the suspended ceiling collapsed including the metal support beams. I got banged up and cut, but nothing serious.

Long story short, I was trapped for almost two hours between floors. Everytime I moved, the elevator would rock back and forth. They had to have a crew go to the roof, through the shaft and attach a cable to the elevator and manually pull the elevator up.

So, there is some kind of safety cable.

 

[chroot]

http://science.howstuffworks.com/elevator4.htm

- Warren

 

[Gara]

also there's meant to be springs and dampers at the bottom of the shaft.

 

[Michael D. Sewell]

I have seen skydiving and construction accidents that have caused horrific injuries. You may not die, but chances are that you will probably wish you had.

 

[ipx`vortex]

how can you jump at the right moment when you're on the ceiling?

you are lighter than the elevator so it'd be might hard to get to the elevator floor in ~10seconds

 

[aychamo]

Originally posted by Michael D. Sewell
I have seen skydiving and construction accidents that have caused horrific injuries. You may not die, but chances are that you will probably wish you had.

Skydiving accidencts such as hook turns? Those damned front risers turns, man they cause so much crap.

 

[Gara]

*kindly points out to ipx`vortex that just because something is heavyer, doesn't mean it falls faster, and that a 20 ton weight would fall at the same speed as an egg, and they would land at the same time*

 

[Integral]

No one has yet mentioned that, given there are no safety mechanisms in place and that the elevator is in a free fall condition, the occupants would also be in a free fall condition. Therefore the occupants are essentially weightless, how do you jump when you are falling? If you did manage to push off of the floor of elevator it would only effect when you stopped, not how fast you are going when the sudden stop occurs.

So, in summary, No jumping would not save you.

 

[cookiemonster]

Do you suppose the terminal velocity of the elevator would be the same or greater than the terminal velocity of the occupant in the elevator? I don't know--I've never seen an elevator fall.

cookiemonster

 

[Integral]

I doubt that the elevator would have time to reach terminal velocity unless the shaft were nearly air tight, then its fall would be considerable restricted. Since the occupants travel in a bubble of still air they would not be subject to forces which create a terminal velocity. Their rate of fall would be the same as the elevators. If the rate of fall of the elevator were restricted then the occupants could get a very good jump off the bottom as their "weight" would be be m(g-r) where r is the acceleration of the elevator.

The fact remains that the jump would only effect when they hit, not their velocity when they do hit.

 

[Michael D. Sewell]

aychamo,
Nobody else here knows about front riser turns, so we should probably skip it for now. Maybe you could start a skydiving thread in the lounge. DOOR! Blue skies, black death. -Mike USPA B-16564

To the rest of you,
M.I.T. and R.P.I. have both had skydiving teams, and have both produced many fine jumpers. I have jumped with many very bright students and grads. Some of them have gotten themselves in some pretty bad situations. It wasn't always a happy ending. You guys have some very interesting ideas, but I assure you, the screaming method seems to be very popular among people trained in physics. In some cases it is as productive as anything else. -Mike

P.S. I never jumped with an egg, but I jumped with a girl who weighed about 20 tons (more or less). She fell really fast!

 

[cookiemonster]

I'll never understand why people jump out of a perfectly good plane.

cookiemonster

 

[Michael D. Sewell]

Because the door is open.

 

[cookiemonster]

I don't get it.

cookiemonster

 

[Michael D. Sewell]

We're getting off subject(my fault). Life is like Indy,
250,000 spectators and 33 drivers. Enjoy your hot dog. -Mike

 

[russ_watters]

Originally posted by cookiemonster
I don't get it.

cookiemonster

FUN. The adrenaline shock so strong that after I landed from my 1 and only jump, I was shaking for like 15 minutes afterwards and had to sit down to avoid falling down. I've never had a rush anywhere close to it (never done drugs).

 

[burak_ilhan]

I assume that each floor is 2.5 meters high, then negleting the force of the air under the elevator(well, i don't known whether it is possible to neglect), you'll hit ground with a speed of 25 m/s.As far as I know human body can resist 25G downward. then if it takes longer then 0.11 seconds you'll probably survive.

 

[Michael D. Sewell]

Survived 3 malfuctions, the first one was a high speed total malfunction. The other 2 were slow rate of descent but much angular momentum. I dealt with each the same:
1.) screamed
2.) found Jesus(alternates are acceptable for other cultures)
3.) pulled appropriate rip-cords/untied 40 million knots(fast)

In the elevator, I doubt one would get any further then #2 before impact. -Mike

 

[Michael D. Sewell]

1.) Run the numbers again, you will find that mine are good given the information available.

2.) You demonstrate, I'll take side bets.

3.)I will use the money to put flowers on the graves of my former friends who fell to their deaths under malfunctions that were going slower than the elevator example.

Believe me, you do not want to hit the dirt going 60 MPH. It's really ugly. -Mike

 

[KingNothing]

Originally posted by chroot
http://science.howstuffworks.com/elevator4.htm

- Warren

Am I the only one annoyed when I read a scientific article use "Centrifugal Force"?

 

[Michael D. Sewell]

Nope.

 

[Gara]

Michael D. Sewell, even if she did way 20 tons, she'll fall just as fast as you. in fact, she'll proberly fall slower, due to less areodynamic ability.

and i forgot about the for ever action there's an equal and opersite reaction. so if the lift is falling at 60 mph you need to jump up at 120 mph.

 

[Michael D. Sewell]

Gara,
Maybe the 20 tons was a bit of an exageration. I have broad shoulders and a slender build, consequently my terminal velocity is about 10 MPH or so slower than most of the other jumpers. Most of the jumpers that have a similar build wear weights and very slick, tight jump suits. Heavy people generally have a ratio of weight/surface area that is greater than thin people, so they fall a lot faster. One time we had a bunch of weight lifters(obvious steroid cases) show up. Boy, they really had a high rate of fall! The jumpmasters had a difficult time keeping up with them. All of them "hammered in" on landing too.
A simple "rule of thumb" that we give students with respect to freefall times is: ten seconds for the first 1000 feet, five additional seconds for each remaining 1000 feet.
I hope this gives you a better understanding of weight, gravity and aerodynamic drag. -Mike

P.S. Hitting the ceiling of the elevator going 120 MPH doesn't strike me(pardon the pun) as being a viable alternative.

 

[AnthreX]

well the 20 ton metal and an egg would fall and hit the ground on the same time

but i don't think it would happen cause of the air resistance
if there wasnt they would probably land at the same time

 

[Gara]

aye that's what I am trying to tell him. yet he seems to believe heavyer things fall faster.

and yes, jumping up at 120 mph would stop you from dieing from the fall of the lift, but presents a new, head smoosh style, problem.

 

[Michael D. Sewell]

What one believes or does not believe has no effect on the laws of physics. If by metal you mean a sphere of solid steel, you are wrong. Steel has a density of 490 Pounds per cubic foot. The density of an egg is not much different than the density of water(62.4 pounds per cubic foot). You can easily check this by placing an egg in a pan of water. What you are missing here is we call in ballistics SECTIONAL DENSITY. I assure you that a block of steel has a much higher terminal velocity than an egg, and would go past it in free fall like a pay car by a tramp.

Acceleration as a function of time
a = g(e^-bt/m)

b = mg/terminal velocity

Integrate this and you will get instantaneous velocity.
Integrate again and you will get the displacement.
-Mike