If one was to jump out of a high building onto a hard surface , one would go splat big time. This is because you have gained kinetic energy due to
gravity.
Now imagine this scenario. You are in a heavy lift and the cable snaps. As the lift falls downwards, half a second before it hits the ground you
jump up. When you push off the floor of the lift, it is heavy enough not to be pushed down, so you have decreased the speed at whcih you are
travelling. You have lost enough kinetic energy so you land gently on the lift floor.
Will you be able to push upwards hard enough to be able to survive?
Whether the "physics" says you can or not, my money is on you not surviving
If the lift is traveling at 50 MPH when it hits and you have just jupmed up at 10 MPH then you "only" hit the ground at 40 MPH. This is assuming the lift doesn't bounce at the bottom.
quote:
Originally posted by 02GF74
If one was to jump out of a high building onto a hard surface , one would go splat big time. This is because you have gained kinetic energy due to gravity.
Now imagine this scenario. You are in a heavy lift and the cable snaps. As the lift falls downwards, half a second before it hits the ground you jump up. When you push off the floor of the lift, it is heavy enough not to be pushed down, so you have decreased the speed at whcih you are travelling. You have lost enough kinetic energy so you land gently on the lift floor.
Will you be able to push upwards hard enough to be able to survive?
quote:
Originally posted by bartonp
Only if you can jump up nearly as high as the lift came down from when the cable broke (ignoring windage).
Phil.
This was tested on a show called Mythbusters.
http://www.youtube.com/watch?v=3biD18ceNuE
quote:
Originally posted by Tralfaz
This was tested on a show called Mythbusters.
Lift falling at 53 mph. crash test dummy jump was 2mph (and hit roof) and in many pieces.
Hit the ground at 50mph...
You could also try stepping out the lift just before it hits the ground...I saw this on Tom and Jerry once, worked a treat.
You would need to jump up at the same speed the lift is falling, but as 'every action has an equal and opposite reaction' (quote I.Newton)
this may only increase the speed of the lift, eg you cannot win!
The way I understand it, your only hope is to increase the time taken to absorb the impact, ie from the time the lift makes contact with the ground
until your body comes to a standstill. A car crashing into a brick wall at 60mph is far more lethal than a car crashing into a pillow factory at
60mph! They both have the same kinetic energy but the 2nd car takes longer to absorb impact.
Not sure how you would apply this in a lift though! 
Iain
[Edited on 17/1/07 by IainB]
Macnab 
I was about to quote the bugs bunny one, but felt it lacked relevance due to Bugs surviving purely becasue the plane ran out of fuel moments before
the impact and therefore stopped in midair (obviously) quality trick!!!
not sure about the lift and it running out of momentum though......
Steve.
Its works!! I saw it on the telly -
Bugs Bunny also saved himself from a plane crash by stepping out the door just as it smash into the ground...
He has actually been nearly killed in 2 plane acidents...
Lucky bunny.
Also apparently you only fall off a cliff when you notice your running in the air, as proved by wile Coyote…
[Edited on 17/1/07 by macnab]
Rescued attachment coyote.jpg
Based on your scenerio next time I am on the point of driving into a stationary car at speed (never tried it, hopefully never will) all I have to do
is quickly slide the seat back on the runners.
- Alan
Blast! just remembered the Locost seat is fixed 
Fortunately lifts can't plummet anymore due to safety brakes, momentum activated. I think I,m right in saying there has only been one plummeting
lift accident since about 1930-odd, when a plane crashed into the Empire State building? I do remember as a kid in Lewis's department store in
Birmingham, the trellis gates of the lifts revealed a giant coil spring at the bottom of each lift shaft. Ever optimistic!
ATB
Phil
Rescued attachment CoyoteGenius.gif
As studied in year 1 Mechanical engineering in Cardiff University!!! If the lift drops at that velocity - you hit the roof at the same velocity, so the chance of you "standing" on the floor is minimal - you will be pushed very hard against the ceiling, and then catapulted into the floor at a very high speed when the lift stops! This usually causes a whole load of horrible death in both instances! Who says students don't learn anything!!!
I've been thinking more about this - donlt think its' gonna work becasue after you jumped up, you will come down due to gravity so you speed
of impace may be even higher.
"Pushed into the ceiling", surely not.
You will fall at the same speed as the lift and accelarate the the same speed as the lift. You will effectivly be weightless in relation to the lift
environment. Any attempt to "jump" will be pretty hard.
Try jumping in mid swimming pool.
If you were in contact with the lift floor and you tried to jump
half the enrgy would be transfered into downward movement of the lift.
You would bash you head on the roof. Not ideal.
Best hope is too attach your braces to the light fitting in the lift as it falls ( you will be weightless) and open your jacket as wide as poss. when
the lift hits the deck the combined wind resistance as you continue to fall and the extention of the elastic in the braces will result in a gentle
touchdown onto the lift floor.
Rlease braces, press door open button and exit.
Simple
Always make sure there's a fat man in the lift before you get in, then you can always stand on him in case of emergencies, soften the blow (for
you at least) 
sometimes you are best off bracing yourself against the front of a falling/crashing object. Imagine, for example, being in a bus as it run into a
wall. If you are unsupported, you fall forwards with an initial velocity the same as the bus'. You then hit something stationary a few moments
later when the bus is at a complete halt. Splat. However, if you brace yourself against something, you will deaccelerate at the same rate as the rest
of the bus, which will then let you take advantage of any crumple zones the bus may have.
I still prefer the fat man approach! Or grab a large breasted woman! Advisable in a near death situation, as it may cause trouble on the street!
quote:
Originally posted by smart51
If the lift is traveling at 50 MPH when it hits and you have just jupmed up at 10 MPH then you "only" hit the ground at 40 MPH. This is assuming the lift doesn't bounce at the bottom.
quote:
Originally posted by Colnago_Man
.... equal and opposite reaction' (quote I.Newton) this may only increase the speed of the lift, eg you cannot win!
quote:
Originally posted by Donkeymatt
As studied in year 1 Mechanical engineering in Cardiff University!!! If the lift drops at that velocity - you hit the roof at the same velocity, so the chance of you "standing" on the floor is minimal - you will be pushed very hard against the ceiling, and then catapulted into the floor at a very high speed when the lift stops! This usually causes a whole load of horrible death in both instances! Who says students don't learn anything!!!
quote:
Originally posted by JoelP
However, if you brace yourself against something, you will deaccelerate at the same rate as the rest of the bus, which will then let you take advantage of any crumple zones the bus may have.
i doubt lifts have crumple zones, but i think they have piston/dampers at the bottom of the shaft so if the lift does somehow manage to fall all the way it will absorb the impact enough so the peeps inside should survive.
Apparently lifts have very big spring loaded brakes that are kept off only by the pull of the cable, so if the cable is cut the brakes jam into the
walls with so the lift can fall a few feet at most. Apparently.
Volunteers?
yep i have heard that too, i beleve lifts have to have at least 8 seperate cables all capable of supporting the lift on thier own, then they have mechanical automatic brakes and if those all fail their are still those dampers/impact absorbers to hopefully allow anyone inside to survive if the lift does fall