The Circular Orbit Velocity using Radius calculator compute the approximate orbit velocity based on the radius of the orbit.

INSTRUCTIONS: Choose the preferred units and enter the following:

• (r)  This is the radius of the orbit.

Orbit Velocity (v): The calculator returns the velocity in meters per second.  However this can be automatically converted to other velocity units via the pull-down menu.

General Information

This equation computes the velocity, `V_"cs"` for a satellite in a circular orbit given the orbit radius, r.

This equation assumes a spherical Earth model and uses the fact that for a circular orbit the semi-major axis equals the radius of the orbit, which is constant.

`V_"cs"`= 631.3481 `r^(1/2)`, where `V_"cs"` is in km/sec.

Notes

For many analyses the spherical Earth approximation is adequate.  See the WGS-84 constants to see some of the the variations in Earth models.

Note that the orbit's radius, r, must be greater than the radius of the Earth `R_e` or else we would be hearing a very strange rumbling beneath or feet.