## orbital velocityThe velocity of an object at a given point in its orbit. If the orbit is perfectly circular, the magnitude of the velocity is constant and given by V_{orb} = √[G(M + m)/r],
where G is the gravitational
constant, M is the mass of the primary gravitating body, m
is the mass of the orbiting object, and r is the radius of the orbit.
In this special case, orbital velocity is the same as circular
velocity. If the m is negligible compared with M, as it is, for
example, in the case of a spacecraft orbiting the Earth, then this equation
reduces to V_{orb} = √(GM/r).
An object moving faster than circular velocity will enter an elliptical orbit with a velocity at any point determined by Kepler's laws of planetary motion. If the object moves faster still, it will travel at escape velocity along a parabolic orbit or beyond escape velocity in a hyperbolic orbit. ## Related entry• orbital energy## Related category• CELESTIAL MECHANICS | |||||

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