Would it be possible.....

[djsy69]

With my very over-active imagination, i was thinking, Would it be possible to jump in a falling lift ( if you knew when the impact was going to be ie. a glass lift) just before the moment of impact to either be
1. not injured at all and land on your feet again,
or
2. enough to reduce your downward speed enough that your legs wouldnt shatter, or your head gets speared on your spine.
Leon.

[Mad Man Dan]

I s'pose jumping just before impact would certainly slow your speed down before impact, however, you would almost certainly still be severly injured, as you would still be carrying a lot of momentum.

Having said that, it would also depend on how high up the lift is when it falls, as if you have reached anything like terminal velocity I can't see a little jump helping you much?

:)

[Ant]

I've stood in a lift and thought about this exact theory - I don't know the answer tho :confused:

[AndyT]

You can't jump any higher in a moving lift than from the floor, can't see it helping much. You still hit the bottom with the same force. If you could jump before the lift moved then the lift would move away and you'd just accelerate till you hit the bottom.:(

[Psycosis]

i asked this question a while back to a few of my mates.
I think you need to have the same speed going upwards to counteract the downward speed.
It was a long time ago so i might have got some of that wrong :)

[andyf]

From pissing about in the lift at work, wouldn't you push the lift ever so slightly faster downwards when you jump as it's not secured and you wouldn't lose any speed at all

[djsy69]

ok then, so say if i was unlucky enough to be on one of the twin towers, from pics on the news part of the spire was still intact, so what would happen to me if i was stood there at that moment in time and also the jumping bit, i doubt i'd make it accelerate faster towards the ground as its too much of a mass for me to move???:( , i know this is a weird topic, although interesting, but i am very morbid, over the last 12-18 months i constantly think about my death, usually 5+ times a day i dont know why, but in this time i have become terrified of it, but before hand i wouldnt give it a second thought:(

[TomM]

Originally posted by djsy69
With my very over-active imagination, i was thinking, Would it be possible to jump in a falling lift ( if you knew when the impact was going to be ie. a glass lift) just before the moment of impact to either be
1. not injured at all and land on your feet again,
or
2. enough to reduce your downward speed enough that your legs wouldnt shatter, or your head gets speared on your spine.
Leon.

If you're in a lift that's falling at (for the sake of argument) 50mph towards the ground, you're also travelling 50mph. Being in a lift doesn't make a difference (as long as the floor doesn't hold miraculous shock-absorption properties) to how it would be falling at 50mph in mid-air, except that there's a floor to potentially jump up from.

Unless:
a) you can jump upwards at said 50+ mph...
b) the lift is actually travelling slow enough for the speed you can jump to counteract your overall falling speed...

...making a little jump will make b*gger all difference!

Of course, if b) is the case, then the lift is falling so slowly it'd make the ones in my residence seem slow, and your ankles would not really be in danger, anyways! :)

And if you did posess Spider-man-esque leg muscles, if you mistimed your jump fractionally, you'd get severely tw@tted by the roof of the lift, travelling towards you at 50mph!

[Still_looking]

No, its all to do with relativity.

If you are sat in the front of a car going 50mph and you throw a ball in the air, the ball does not accelerate to the back of the car does it? Why, cos' its going the sane speed as the car and there is no outside force (Wind) acting on it. Same for a lift.

The lift is dropping at 30mph, you are also travelling at the same speed, if you jump, say at 3 mph (your speed drops to 27mph while you are going up) you are still going to be going down at the same speed as the life when the energy from the jump expires - you speed is relevant to the lift. You'll still be pulped when it hits the ground.

How ever, if the lift had mesh on the top and bottom and air was rushing through it..

[Nick_Walczak]

I'd say it is (assuming the lift doesn't pancake :) ). The shock would be transferred into the lift floor and throughout it's structure. It's different to freefalling in that the air around you moving at the same speed as the lift. There would be some shock transferred to the air but this would be very mild. Just a loud noise really.

[Phil L]

ditto Still_Looking.

[Vipers]

we done this in our physics class a year ago cuz we thought the same.

the lift is say 50 metres high, the cable snaps.

the lift acclereates downwards @ 9.81 ms-²
you accelerate downwards @ the same rate because you can ignore weight becasue the acceleration due to gravity is the same for a body of any mass. weight doesn't make any difference.

since you are falling your feet may or maynot be touching the floor depends if you tried to jump just as it started to fall ( altho i suppose you could raise your legs as it were and they would no longer be touching the floor) this is all assuming that the lift is free falling and by this i mean there are no frictional forces acting upon it other than air risistance. like it rubbing agaistnt the sides of the shaft

but basically you can't really save your self you'll always break some bones but if you keep you leghs ready to bend while you feet are still touching the floor you'll increase you chances.

i think the equation you'll need if you wanted to work out your speed/ velocity just before you hit the ground is

v = final velocity

u = starting velocity

a = acceleration

s= displacement or distance

since gravity = acceleration i'll put g in there

and since the lift would be at rest before comencing its descent starting velocity = 0

v² = u² + 2as

v² = 0 + 2 x g x distance traveled

v² = 0 + 2 x 9.81 ms-² x 50 (using example above in metres)

v²= 2 x 9.81 x 50
v²= 119.62
v = square root of 119.62
v = 10.94 ms-¹

round it upto 11 metres per second

so in mph it will be 24.6 mph if i converted it correctly

[Martin T]

If the lift wa only travelling at 25MPH, then jumping at the right time could make the difference between brocken legs and not brocken legs in that example.

[davidra]

I think you're best off putting some padding under your head and lying on your back on the floor, perhaps braced against the walls. That way your body isnt going to be hitting other parts of your body, wrenched, strained etc it'll just be the sharp deceleration on all parts of your body simultaneously.

[mook]

*lol* @ davidra > sounds good to me.

Reminds me of the old story about NASA spending a fortune developing a pen that could write in zero gravity. The Ruskies, on the other hand, used a pencil :D

[TAS]

This has just triggered something...

how about this...

You are on a train and you are going 60mph.. you lean out facing the opposite way and throw a stone at 60mph...
A person is standing exaclty where you threw the stone...

Question time: what happens to the stone?


Answers on a post card...:rolleyes:

[davidra]

Is the stone going 60mph relative to you or the observer?

[Nick_Walczak]

I don't agree about the lift. If you aren't in contact with the lift floor when you hit, no shock will transfer to you. This is not the same as freefalling and hitting the ground because the air you are in is not moving relative to you so what is it that hits you?

[JonnyBoy]

Ive often (well ok, not that often) wondered what would happen to a fly in your car with the windows open. If it was flying full belt forwards and you were going at the same speed would it stay still?

[davidra]

Even if you are not in contact with the lift floor when the lift floor hits, you will be a few seconds later - even if you manage to reduce the impact slightly by jumping! When you hit the lift floor I think you would be less damaged than by a standing impact - damage would be caused by your feet stopping relative to your ankles, damaging your ankles; your ankles then stop(/slow down) relative to your knees, damaging your knees & so on up your body (I know this is a simplification but you get the idea - that differential deceleration over your body would be harmful?).

[Nick_Walczak]

Actually, you are right. :D Thinking about what happens to a fly inside your car helps. If you brake hard, the fly is thrown forwards even though it's surrounded by air that is not moving relative to it - the force of deceleration still applies.

[Phil L]

I think Tim was asking something like this...(taken from howstuffworks)


You may have heard of Newton's first law:

"Every body persists in its state of rest or of uniform motion in a straight line unless it is compelled to change that state by forces impressed on it."

We could rephrase this a little and say that a body in motion tends to stay in motion and a body at rest tends to stay at rest unless acted on by an external force.

Imagine you are on a perfectly smooth speeding train, moving at a uniform speed (not accelerating or turning), in a car with no windows. You would have no way of knowing how fast you are going (or if you were moving at all). If you throw a ball straight up in the air, it will come straight back down whether the train is sitting still or going 1,000 mph. Since you and the ball are already moving at the same speed as the train, the only forces acting on the ball are your hand and gravity. So the ball behaves exactly as it would if you were standing on the ground and not moving.

So what does this mean for our gun? If the gun shoots bullets at 1,000 mph, then the bullet will always move away from the gun at 1,000 mph. If you go to the front of a train that is moving at 1,000 mph and shoot the gun forward, the bullet will move away from you and the train at 1,000 mph, just as it would if the train were stopped. But, relative to the ground, the bullet will travel at 2,000 mph, the speed of the bullet plus the speed of the train. So if the bullet hits something on the ground, it will hit it going 2,000 mph.

If you shoot the bullet off the back of the train, the bullet will still be moving away from you and the gun at 1,000 mph, but now the speed of the train will subtract from the speed of the bullet. Relative to the ground, the bullet will not be moving at all, and it will drop straight to the ground.


In answer to JonnyBoy question, from the above it would seem the fly would hit your windscreen if it flew forwards. The fly would be travelling at the same speed of the car, plus its own speed. The window being open or not wouldn't make much difference because the fly is inside the moving car.
If the fly went outside the window, then it would only seem to stop moving if it managed to match the speed of your car, in that split second when it left the inside to outside.

phew, I need a rest now...

[Vipers]

if windows are open i'd say the bug would either splatter where it is as in explode/implode which ever applies

ort it woould get sucked out of the window

reason being is bernoullis pressure rule.(can't rmeber what it is actually called just remeber he thought of it and is the reason why things fly)

fast moving air has less pressure than slow moving air. therefore
imagine an airplanes wing on a cross section view

air flowing over the top has more distance to travel than the air flowing beneath. for soemreason that i have forgotten the air that travels upto the front of the wing then splits in 2 1 going over top and 1 beneath these two airflows must meet up at the other endthewrefore top side airflow must treavel faster

and because its travelling faster means that it has less pressure than the bottom and its this diffewrtence in pressure that cause the wing to lift and there fore the plane ( also effecting the wing is the angle of attack which is a law of momentum but wont go into that cuz doesn't apply)

so basically the air out side the car is travelling faster than the air inside so there is pressure in the car than outside ( one reason why your ears pop when driving fast) so when the window is opened the difference in pressure cause the air from within the car to be sucked out like when *****ing a baloon

and is also the reason why you hear a funny noise when doing around 80+ with windows open its the air being sucked out of the car

[davidra]

so when the window is opened the difference in pressure cause the air from within the car to be sucked out like when *****ing a baloon

Which is why on the S13 the frameless windows sometimes open a bit at the top at speed unless you adjust them to press quite tightly against the rubber door-pillar/roof bits...

[Jon]

Djsy69:

Perform the experiment and post photo evidence. Or get your next-of-kin to do it.


My wallpaper at work is now "chameleon on mirror"

[djsy69]

Originally posted by Jon
Djsy69:

Perform the experiment and post photo evidence. Or get your next-of-kin to do it.


My wallpaper at work is now "chameleon on mirror"

LOL :D :D :D :D


heres another pic then.

[djsy69]

and another

[Leon]

BUMP

Too many newbies who haven't yet seen the SXOC wisdom