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## Homework Statement

Ringworld is an artificial world constructed in the shape of a giant ring that rotates around a star similar to our sun. The radius of the ring is 1.53x10^11m (from the sun to the ring). The mass of ringworld is 2.1x10^27kg and its simulated gravitational acceleration is 9.73m/s^2. Determine how fast the inner surface of the ringworld is moving to experience a "gravitational" (no idea why this is put in quotations in the question) acceleration of 9.73 m/s^2.

Gravitational constant=6.67x10^-11

## Homework Equations

V

_{centripetal}=2πr/T

A

_{centripetal}=v^2/r or =4π^2(r)/T^2

F=Gm

_{1}m

_{2}/r^2

g=Gm/r^2

T

_{1}^2/R

_{1}^3=T

_{2}^2/R

_{2}^3

Any combination of the above also work.

## The Attempt at a Solution

How do you find the mass of the central body and the orbital period? It seems impossible to do anything without knowing one or the another. I don't know where to start.

Any help is appreciated. Thanks.