# Odd Question, kind of physics related

Mexico
Posers and Puzzles 02 Feb '08 07:09
1. Mexico
Quis custodiet
02 Feb '08 07:09
Firstly I know the practicalities of this are ridiculous. But I asked my physics teacher in school and Never got a satisfactory answer. Then I forgot to ask one of my physics lecturers in college, and then dropped physics for geology anyway.

If one was to build a ring shaped object with a diameter 1 meter longer than the Earths Diameter (Taken as a constant which it isn't) would it hover above the surface? and if so at what height, I know the second part is simple to work out but I'm not even sure about the hovering in the first place, It seems like such a weird Idea in the first place.
2. coquette
02 Feb '08 07:47
it would hover at the same height that a ring around 1 point would hover.

Circumference = pi X diameter (Radius X 2)

Radius = 1 Meter/2 X pi (3.14 feet)

very approximate

(I'm not a mathematician, so a correction would be appreciated)
3. Mexico
Quis custodiet
02 Feb '08 08:16
I know it can be worked out relatively simply, however will it hover is the real question. Theres little reason why it shouldn't around a perfect sphere with uniform gravity, however the Earth is neither....
I am however assuming you can find a circumference around earth which has uniform-ish topography. Which doesn't exist. So although the question is kind of pointless in an real sense being able to generate a hovering ring around the earth does have some interesting ramifications......
4. 02 Feb '08 09:19
This is how I would answer the question in hand ... by making a parallell:

Is it possible to make a pole with a point sharp ending stand vertically without falling? The answer is: Yes, if you put it there in an exact position. Is it practcally possible to do that? No, only in theory. In practice it will fall down eventually.

What do we mean with exact position? It means that you put it there in an angle of 90.0000... (infinit number of zeroes) degrees compared from the horizontal gorund. And with any impurity in symmetry, other forces, or anything else there will be 89.nnnnn... (infinit number of decimals) degrees. Now, the exact angle is not possible to evaluate until the last decimal, therefore it will fall eventually. But if you could, then the pole will stand there forever. But you cannot.

The same thing with the thorus around the globe. If you place it there in an theoretical exact position, with regards of gravitaional asymmetries, inhomogenous material, and other factors you know or don't know about, then it will hoover over the ground eternally. In practice you cannot.

5. wolfgang59
02 Feb '08 13:41
Originally posted by FabianFnas
This is how I would answer the question in hand ... by making a parallell:

Is it possible to make a pole with a point sharp ending stand vertically without falling? The answer is: Yes, if you put it there in an exact position. Is it practcally possible to do that? No, only in theory. In practice it will fall down eventually.

What do we mean with exa ...[text shortened]... n it will hoover over the ground eternally. In practice you cannot.

Good analogy but is it true?

If the ring slipped from its hovering position so that one part touched the Earth would it be stable there? I think not. My instinct is to think that it would oscillate and therefore the pointy pole analogy is not a good one.

Anyone brave enough to do the math?
6. 02 Feb '08 14:12
Originally posted by wolfgang59
Good analogy but is it true?

If the ring slipped from its hovering position so that one part touched the Earth would it be stable there? I think not. My instinct is to think that it would oscillate and therefore the pointy pole analogy is not a good one.

Anyone brave enough to do the math?
Well, true or not, it will not finding a stable point hoovering above the surface at every location around the ring.

I think it will find its minimal energy position eventually (perhaps after an occilation, or not), and that one is not in a hoovering state.

I say that any math done has to rely of simplifications so the solution is not worth very much in the practical world, and therefore meaningless.
7. wolfgang59
02 Feb '08 14:19
Originally posted by FabianFnas
Well, true or not, it will not finding a stable point hoovering above the surface at every location around the ring.

I think it will find its minimal energy position eventually (perhaps after an occilation, or not), and that one is not in a hoovering state.

I say that any math done has to rely of simplifications so the solution is not worth very much in the practical world, and therefore meaningless.
Theoretical problems often have practical implications. Someday in the future huge rings may be built surrounding moons and planets!
8. 02 Feb '08 14:21
Originally posted by wolfgang59
Theoretical problems often have practical implications. Someday in the future huge rings may be built surrounding moons and planets!
I don't think so. Unless theyhave a expensive orbit correction devise at the same time. And what is the point of having such a ring?
9. wolfgang59
02 Feb '08 14:40
Originally posted by FabianFnas
I don't think so. Unless theyhave a expensive orbit correction devise at the same time. And what is the point of having such a ring?
I have no idea ... but then the Victorians would have had no use for a microchip and a caveman no use for a steam engine!

10. 02 Feb '08 14:51
Originally posted by wolfgang59
I have no idea ... but then the Victorians would have had no use for a microchip and a caveman no use for a steam engine!

Yes, I see what you mean, but is there not any use for a thorus satellite around the globe, then what's the point in constructing such an expensive thing?

Well, Garlic Icecream is also a possibility. But only because we can do it, does that really imply that we also have to do it? No, I don't think I am narrow minded.

Only a need for constructing a new thing is the motivation for doing so. Microchip? Yes. Steam machine? Yes. Garlic ice cream? No.
11. wolfgang59
02 Feb '08 15:39
Originally posted by FabianFnas
Yes, I see what you mean, but is there not any use for a thorus satellite around the globe, then what's the point in constructing such an expensive thing?

Well, Garlic Icecream is also a possibility. But only because we can do it, does that really imply that we also have to do it? No, I don't think I am narrow minded.

Only a need for constructing a ...[text shortened]... hing is the motivation for doing so. Microchip? Yes. Steam machine? Yes. Garlic ice cream? No.
What need did the caveman have to construct a steam engine? My whole point is that just because we do not have the need now, nor the imagination to conceive of that need, does not mean it will not arise in the future!!

AND DON'T KNOCK GARLIC ICE-CREAM UNTIL YOU'VE TRIED IT!!
(Chilli ice-cream is good too)
12. 02 Feb '08 15:451 edit
Originally posted by wolfgang59
What need did the caveman have to construct a steam engine? My whole point is that just because we do not have the need now, nor the imagination to conceive of that need, does not mean it will not arise in the future!!

AND DON'T KNOCK GARLIC ICE-CREAM UNTIL YOU'VE TRIED IT!!
(Chilli ice-cream is good too)
They have no need for a steam machine. If they did have a need, they'd buld one.

Who will finance a thorus around the globe if there is no need for it? But if there really is a need for it, then it will be constructed, I'm sure.

There is a need for a manned moon station, but there is no financiers, therefore, a manned moon station is not constructed. Yet.

(I don't think really there is a market for a garlic ice cream.)
13. wolfgang59
02 Feb '08 16:24
Originally posted by FabianFnas
They have no need for a steam machine. If they did have a need, they'd buld one.

Who will finance a thorus around the globe if there is no need for it? But if there really is a need for it, then it will be constructed, I'm sure.

There is a need for a manned moon station, but there is no financiers, therefore, a manned moon station is not constructed. Yet.

(I don't think really there is a market for a garlic ice cream.)
http://www.garlicworld.com/icecream.html
14. 02 Feb '08 17:30
Originally posted by wolfgang59
http://www.garlicworld.com/icecream.html
ðŸ˜›
15. AThousandYoung
All My Soldiers...
02 Feb '08 18:31
Originally posted by FabianFnas
They have no need for a steam machine. If they did have a need, they'd buld one.

Who will finance a thorus around the globe if there is no need for it? But if there really is a need for it, then it will be constructed, I'm sure.

There is a need for a manned moon station, but there is no financiers, therefore, a manned moon station is not constructed. Yet.

(I don't think really there is a market for a garlic ice cream.)
All you have to do is point out that garlic is thought to give resistance to disease...