- #1

- 565

- 2

## Main Question or Discussion Point

If two bodies are moving about a common point, with one orbiting the other, in a completely circular orbit, from knowing just their periods (which are equal) and the graviational constants of each body times mass, how would you determine the radius of each of their circular orbits?

You can get the velocity as a function of the period and radius.

And for circular orbits vo=sqrt(GM^2/ro)

But since the inner body's position is constantly changing you can't straight forwardly apply the above equation to the outer body can you?

And for the inner body it would be in circular rotation about a point below its surface, so I'm not sure how you would apply the equation in that situation.

You can get the velocity as a function of the period and radius.

And for circular orbits vo=sqrt(GM^2/ro)

But since the inner body's position is constantly changing you can't straight forwardly apply the above equation to the outer body can you?

And for the inner body it would be in circular rotation about a point below its surface, so I'm not sure how you would apply the equation in that situation.

Last edited: