My theory.

[Axle]

Okay I've had this theory a while and wanted to know if you would think it'd work.

If you got a helicopter and lots of petrol and flew up and stopped.

Would you travel acrossthe world in one day?

Because the earth rotates or would you stay in that spot?

[SirNadroj]

Okay I've had this theory a while and wanted to know if you would think it'd work.

If you got a helicopter and lots of petrol and flew up and stopped.

Would you travel acrossthe world in one day?

Because the earth rotates or would you stay in that spot?

What about the wind? :-P

I doubt it. ;-)

[Starwars4J]

Well, think of it this way, Axle. When you jump up, does the ground move under your feet? The Earth rotates, and fast too! So you'd expect if you jumped, that you'd slam into the nearest wall!

The answer is that it isn't the wind (:-P) but rather that you're in the atmosphere. It's the same as the Earth, meaning that the whole thing rotates. Anything in the atmosphere will rotate at the same speed as the Earth, and therefore, would not move with respect to the ground.

This would work, however, if you escaped the atmosphere, like the space station does (I'm sure you've heard of satellites passing overhead and whatnot). Hope this answered your question!

You still have something in your eye, SN? :-D

[SirNadroj]

The answer is that it isn't the wind (:-P) You still have something in your eye, SN? :-D

I think the wind blew a helicopter into it, but I can't get it out! ;-)

;-)

;-)

;-)

:'-(

[natelite]

not quite. you see, newton's law: a body in motion tends to stay in motion. it's the momentum rule. when you are on the earth, you are rotating with it. when you jump you exert an upward force which propels you upwards. but you still have that rotating momentum from earlier, so when gravity pulls you down later, you land in exactly the same spot because you were rotating at the same time as the earth.

so for a helicopter to stay up in space, in a counter rotational direction, it needs to overcome its momentum, then it needs to overcome the atmosphere's momentum immediately surrounding it. so to truly stay "stationary" in space ( i use that term loosely since space and time is relative, not absolute) the helicopter actually needs to move counter rotation to the earth. so if it only exerts a vertical force, it will still rotate with the earth therefore will not actually circle the earth at all.

now if you assume a helicopter stays high up in the statosphere where there is no friction, no air resistance, well... that's an impossible situation. a helicopter can't stay up without any air. :-/ it's the forced compression of air that exerts a downward force which allows it to stay "afloat."

to stay in "space" forever you actually need to stay at a trajectory tangent to the earth and at just the right speed. the gravitational force will pull you towards earth, pulling you from your initial trajectory away from the earth. if this relationship maintains, you should stay up above the earth in a "constant spot" as viewed from the earth below. :-P

[Starwars4J]

Well that's more or less what I said, the atmosphere rotates with the Earth, in effect making it one entity. However the force you exert back on the Earth doesn't have anything to do with this. When you jump, the momentum you have, as well of that of the atmosphere, keeps you going at the same rate as the Earth. If the atmosphere were to somehow cease it's relationship with the Earth, you'd actually be moved back a bit due to air resistance.

For a heli to remain stationary you'd have to travel in a counter-rotational direction at the exact same speed as the Earth rotates. Not only that, to remain stationary in space, you'd quickly leave Earth's atmosphere entirely, due to it's revolution...but that's not what he was talking about, was it? :-P

to stay in "space" forever you actually need to stay at a trajectory tangent to the earth and at just the right speed.

Well, you'd need to be tangent to the Earth's rotation, not just the Earth, as you could go with the rotation as well...or perpendicular to it ;-) But that just gets back to what I said earlier about the counter-rotational speed...

[Opproperaar]

We actually saw this this week in geography. The cool thing is, seeing as the Earth rotates around the poles (with the poles being the one place where you don't move at all and the equator being the one where you move fastest) we were able to calculate the speed at which you move when you're standing at the equator.

1,666 km an hour.

Fast no?

Edited November 9, 2007 by Hairy Ruben

[Lord Of Pies]

1,666 km an hour.

Fast no?

Gah, sign of the devil, 666!! :-D

I think that Starwars4J and Natelite have summed it up pretty well. *y*

[Norro]

What always interested me more is that when you jump, due to gravitational attraction and counting the earth as a point mass rather than having atmosphere, the earth moves negligibly towards you as you move significantly towards it. The only reason it seems stable is it's far greater mass. So if a lot of people jumped... X-D

God Bless,

Nathan

[Shadows]

Speaking of crazy theories, I've got one I was never able to quantify.

You're riding in an elevator going down. 78th floor. As the floors pass, it gets faster and faster until you realise you're in freefall.

This isn't your ordinary elevator, it's open to the elements on the outside wall (yes, I know, just humour me).

Riding the elevator to the ground will kill you, obviously. Can you jump off at some point near the ground and actually minimize some of the damage, or ...

Remember the thread about good posting where I said I abort 1/3 of my messages? This should have been one of them. :-|

Crazy On! X-D

[Stauder]

Hmmm... Theoretically? Maybe... *Phones up mythbusters* Uhuh.. Hmm? Yes... Mhm... Ok...

They asked if you took your medication this morning... :-P

[Shadows]

Hmmm... Theoretically? Maybe... *Phones up mythbusters* Uhuh.. Hmm? Yes... Mhm... Ok...

They asked if you took your medication this morning... :-P

I can bust that myth for them myself. Not all of us crazy people even have medication to take! HA! :-P

[Norro]

Speaking of crazy theories, I've got one I was never able to quantify.

You're riding in an elevator going down. 78th floor. As the floors pass, it gets faster and faster until you realise you're in freefall.

This isn't your ordinary elevator, it's open to the elements on the outside wall (yes, I know, just humour me).

Riding the elevator to the ground will kill you, obviously. Can you jump off at some point near the ground and actually minimize some of the damage, or ...

Remember the thread about good posting where I said I abort 1/3 of my messages? This should have been one of them. :-|

Crazy On! X-D

Depends on the volume of the elevator ;-)

As I understand your theory you're comparing the critical velocities of you and the elevator, so the only real varying factor is the mass to air resistance ratio...

God Bless,

Nathan

[snefroe]

Depends on the volume of the elevator ;-)

As I understand your theory you're comparing the critical velocities of you and the elevator, so the only real varying factor is the mass to air resistance ratio...

God Bless,

Nathan

i'm only a simple historian, so don't shoot me if i'm not making any sense...

Wouldn't you, as a human being, just crash against the ceiling of the elevator?

[Axle]

*y* Good point!

Lol.

[Shadows]

i'm only a simple historian, so don't shoot me if i'm not making any sense...

Wouldn't you, as a human being, just crash against the ceiling of the elevator?

You're forgetting that there's an entire open wall in this fictional elevator X-D

But you bring up a good point!

If, in fact, you did sort of achieve a temporary weightlessness, could you open the hatch at the top of the elevator, climb up, and then jump just before it hits?

I know better, but my mind just wants to believe in this, no matter how wrong it is. *wacko*

Watch, they'll pull this stunt in a Bond movie and I won't even get credit. Of course he'll have a grappling hook in his Rolex (how exactly does that not snap his wrist when it's pulling him up?). Wait, who am I to be doubting that when I've got a crazy elevator theory... :-$

[oo7]

Ah yes, one does in fact obtain a weightless state when moving at high velocity towards an extremely large concentration of mass such as freefalling in an elevator towards or below Earth's surface for a sustained period of time (this concept is the same reason why one is weightless in outer space). However, this period is even still very brief regardless of how sustained it would have to be so I'd think one has very little chance of opening a hatch at the top or managing to jump out expecting to carry out a safe landing.

[Starwars4J]

They actually did do this with mythbusters once...

Basically you'd need to jump up with the same (or greater) velocity than the elevator is falling. Even though you're jumping up at say, 1 m/s, the elevator is still going down at 80 m/s, therefore you're still falling at 79 m/s.