I work it out below, but the resulting ring is ~20% larger than earths orbit about the sun. Yeah, surprised me too (thinking I may be missing a decimal point...but I'm not seeing it...). I was guessing something large, but not quite that large. Say you want to do it in 60seconds, you're looking at only 900m radius. 6 seconds is about 9 meters.

The key factor: The really slow rotation rate. Bring that down, and you don't need a ring nearly so large. The derived equation to tell you the radius of a ring needed, given the time of rotation is: R = A*T^2/4pi^2 (A in this case being 1g, or 9.8m/s^2)

on a side note, I just worked out the centripetal force of a ring at geosynchronous orbit (i.e. what's the acceleration of a ring at geostationary orbit, rotating 1/day..the sci-fi holy grail of space docks...is only 0.18m/s^2)

Working out the details if you're interested:

Centripetal acceleration is A = v^2/R, and we want that to equal 9.8m/s^2, and you're asking for the radius required for it to require only on rotation in a day.

So V = Distance/Time, time in this case is 24 hrs = . So whats Distance? It's the circumference of a circle, so 2*(pi)*R.

so, plugging things in we get A=(2piR)^2/(T^2*R) = 4*pi^2*R^2/(T^2*R) = 4*pi^2*R/T^2

Rearranging so that R is solved for (not A) we get: R = A*T^2/4pi^2

A = 9.8 m/s^2

T = 24hrs = 86400 seconds --> T^2 = 7464960000s^2

4pi^2 = 39.4

A quick check to make sure the units come out right...R is in m, AT in m/s^2 * S^2 giving us M...so that works out (don't want a distance in seconds or velocity after all).

Plugging the numbers in...

39.4*R/7464960000 = 9.8

R=90*7464960000/39.4 = 1856766700 meters - 1856766 km...round out to significant figures (make it neat and tidy) and we get ~1,850,000 km radius

To make that number more meaningful, earth's radius is only ~6,000 km...so we're looking at a ring ~310,000 times the earths radius...

Still to big to really get your head around. An astronomical unit (distance between the earth and the sun) is ~150,000,000 km .... So this ring is just a bit larger than earths orbit....spinning at 1 revolution a day.

Looks like I was right, double checking turned up

this site that has an online calculator. Just turn 1/day into rotations per minute (1/(24hrs*60min)...or 0.00069 rpm and set the mass to 1kg. Mess with the radius until you get 9.8N of force (which is 1g acceleration on 1kg of mass)...which matches my huge radius.