Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Cable that holds the elevator got disconnected

  1. Mar 13, 2004 #1
    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 ?
  2. jcsd
  3. Mar 13, 2004 #2
    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.
    Last edited by a moderator: Mar 13, 2004
  4. Mar 13, 2004 #3


    User Avatar
    Science Advisor

    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".
  5. Mar 13, 2004 #4
    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.
  6. Mar 13, 2004 #5
    Interesting idea. I wouldn't recommend that you demonstrate it without changing the current design that is commonly used.
    Last edited by a moderator: Mar 13, 2004
  7. Mar 13, 2004 #6
    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.
  8. Mar 13, 2004 #7
    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
    Last edited by a moderator: Mar 13, 2004
  9. Mar 13, 2004 #8
    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.
  10. Mar 13, 2004 #9
    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?
  11. Mar 13, 2004 #10


    User Avatar

    Staff: Mentor

    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.
  12. Mar 13, 2004 #11


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

  13. Mar 14, 2004 #12
    also theres meant to be springs and dampers at the bottom of the shaft.
  14. Mar 15, 2004 #13
    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.
  15. Mar 15, 2004 #14
    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
  16. Mar 16, 2004 #15
    Skydiving accidencts such as hook turns? Those damned front risers turns, man they cause so much crap.
  17. Mar 16, 2004 #16
    *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*
  18. Mar 16, 2004 #17


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    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.
  19. Mar 16, 2004 #18
    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.

  20. Mar 16, 2004 #19


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    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.
  21. Mar 16, 2004 #20
    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!
    Last edited by a moderator: Mar 16, 2004
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook