# Circular Orbit Velocity using r only

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V_"cs" =
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vCalc.Circular Orbit Velocity using r only
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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.

This equation, Circular Orbit Velocity using r only, is listed in 1 Collection.