Need help generating gravity

[Sayonara]

There would be no gravity on the inside of the ring. Assuming a uniform mass distribution' date=' gravity depends on the mass inside of your radius. This is from Gauss's law (used also in electrostatics - if the ring were charged there would be no electric field inside, either)

 

Whatever pull there is from the mass below your feet, it is counterbalanced by all the mass elsewhere in the ring. The sideways pull cancels from symmetry, but the up/down cancels, too. Even though a lot of the ring is far away, there's a lot of it compared to what's below you.[/quote']

A Halo is only any use if the living area assumes the same position in space as the average position of the surface of a planet that would be able to support life. IE - the ring needs to be approximately the same size and shape (although probably less of an elipse) as an "M-class" planet's orbit.

 

The assumption with these things (unlike the Dyson sphere, which requires technological workarounds nobody has explained yet) is that the ring rotates like an enormous bicycle wheel.

 

Would it ever get fast enough to keep people "pinned" to it, or would people eventually end up drifting into the sun?

[ski_power]

Would it ever get fast enough to keep people "pinned" to it, or would people eventually end up drifting into the sun?

 

Now that's a good thought. It sounds serious, but after a second look it sounds funny too.

I guess it should "spin" fast enough to keep the people from drifting away.

7919.59594928933 m/s should be the approximate velocity it should travel to give earth like gravity(assuming that it's inner radius is the same as that of the earth, and using a=(v^2)/r). Does Earth spin that fast?

[swansont]

But wouldn't Centripetal Acceleration give us gravity on the inside part of the ring? Assuming it is rotating along it's principal axis, ie perpendicular to the plane through the centre

 

Technically, no. But it would give an acceleration indistiguishable from gravity. You'd have "I can't believe it's not gravity!"

[swansont]

Now that's a good thought. It sounds serious' date=' but after a second look it sounds funny too.

I guess it should "spin" fast enough to keep the people from drifting away.

7919.59594928933 m/s should be the approximate velocity it should travel to give earth like gravity(assuming that it's inner radius is the same as that of the earth, and using a=(v^2)/r). Does Earth spin that fast?[/quote']

 

If the earth spun so fast as to make the centripetal acceleration equal to g, we'd feel weightless (think astronauts in orbit) - so the answer has to be no. The earth spins at about v=40,000 km/86400 sec = 463 m/s at the equator.

[ski_power]

But that gives a CPA of hardly 0.03349515625 m/s^2, then how is it able to produce g(other than the Principle of Attracting bodies).

What if we lived in the inner part of the ring, then how much CPA would be needed to simulate near-earth gravity, assuming all identical earth properties.

And also, how come in the Astronaut Centrifuge, they are able to produce higher g that too with help of acceleration,

[swansont]

But that gives a CPA of hardly 0.03349515625 m/s^2' date=' then how is it able to produce g(other than the Principle of Attracting bodies).

What if we lived in the inner part of the ring, then how much CPA would be needed to simulate near-earth gravity, assuming all identical earth properties.

And also, how come in the Astronaut Centrifuge, they are able to produce higher g that too with help of acceleration,[/quote']

 

I'm not sure I understand the question - the value of ~8000 m/s would give ~1g for someone on the inside of the ring. That the earth rotates more slowly than this means we stick to the earth, rather than have a really low orbit around it. (ignoring the strong possibility that the earth wouldn't hold together at 8000 m/s)

 

We feel 1g on the earth because of the earth's mass and radius. The rotation actually decreases what we measure as our weight, by a fraction of a percent. But, as your numbers show, we can ignore the rotation for general discussions, since it's a small effect. To simulate earth's gravity, we'd need just under 8000 m/s, and be on the inside of the ring.

[ski_power]

Hey swansont, if the earth rotated at 8000m/s then it would act like a HUGE centrifuge. And then after a few million years, wouldn't earth become a torus?

[swansont]

Hey swansont, if the earth rotated at 8000m/s then it would act like a HUGE centrifuge. And then after a few million years, wouldn't earth become a torus?

 

No. Gravity at a radius R is dependent on the mass inside of R (for a uniform distribution). A torus has no mass inside, thus no gravity to hold it together. You might end up with a smaller planet that has rings, but that would depend on a lot of things.

[YT2095]

that effect is precluded by Gravity, however there is a very slight distortion, making the Earth not exactly a perfect sphere

[ski_power]

Hey wait, just for confirmation isn't torus a doughnut, with a hole in the centre?

This one

According to common sense, if the earth is flattened at the poles, due to spinning at the equator, shouldn't the same force assist further flattening of the planet?

[swansont]

Hey wait' date=' just for confirmation isn't torus a doughnut, with a hole in the centre?

 

According to common sense, if the earth is flattened at the poles, due to spinning at the equator, shouldn't the same force assist further flattening of the planet?[/quote']

 

Mmmmmm...donut

 

Flattening the earth is not the same thing as forming a torus. A disk still has mass in the center, but a torus does not.