It's been too long sense my last physics class. I've tried the math
and i think the answer to my question is dissapointing. Here goes...

I want a ring around the earth with the following properties.
The ring is around the earths equator. 
Any given point on the ring is always above the same spot on the equator.
standing on the inner surface of the ring provides enough acceleration
to overcome whatever the pull from earth exists at that altitude.
My ideal situation is  one where a person sitting on the inside of the
ring experiences 1g towards the stars but any force is better than
none.

I want to know a couple properties of the ring if it's possible. 
*Speed of a point on the ring relative to a (relatively:-) stationary observer.
*Radius of the ring.
*Calculations ignoring the moon/sun/planets are OK but i'de like to
know how significantly the moon would affect someone standing on the
inside of the ring.

Like i said i've done what math i know how to do and unless i have not
forseen some posibility i think that there is no magic radius that
provides those things.

Of course you can totally ignore tensile strength but knowing the
tensile strength would be super cool :-)

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Clarification of Question by egon_spangler-ga on 09 Jan 2006 19:44 PST

I hadn't thought about a ring that was MUCH bigger than earth's
significant gravitational field. I was really looking for something
inside the orbit of the moon where the forces are balanced against
eachother.

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Clarification of Question by egon_spangler-ga on 09 Jan 2006 19:44 PST

Ringworld was GREAT! The sequels were worth reading (I'm a big niven
fan) but not as great as the first.

The angular velocity (w) is 7.292 * 10^-5 rad/sec.

centripetal acceleration is equal to w^2*r.  (r is radius)

So, you want w^2*r = g, or r = g/w^2.    

g = 9.81 m/s^2, so r = 1845000000 m, or 1.85 million km.
(at that distance the gravitational attraction of the earth is
negligible compared to the centripetal acceleration, so it's ok that
we ignored it.)

That is about 5 times the radius of the moon's orbit about the earth.  

In order to calculate the required strength, you have to specify the
mass of the ring.

The radius of geosynchronous orbit is 42,000 km.  There would be a net
outward force on objects on any ring larger than this.  But the
outward acceleration only approaces 1 g for rings much larger than
this.

You will love Larry Niven's Nebula Award winner, "Ringworld." Don't
bother with any of the sequels.

I've got a question.... What are the equations for calculating
artificial gravity, mass, radius, required velocities, tensile
strengths, etc.?  For that matter, how do I use them?