Average
velocity = Zero.
- if you're using Earth as the frame of reference.
Its
speed can be calculated if the orbit height is known.
P= 2 Pi (a^3/u)^1/2
P: orbital period
a: the semi-major axis of the orbit (same as the radius of the circle for a circular orbit!)
u: gravitational parameter ( ~398601 km3 / Sec2 for Earth)
dist = 2 PIE r
r: orbit radius = orbit height + Earth's own radius
speed = dist / time = 2 PIE r / P
A shortcut:
For near Earth orbits, if distances are measured in Earth radii, the circular orbital speed is
Speed= 7.907 A^-½ km/s
A = units of Earth radii
This is because the speed inversely to the square of the orbit radius. At the Earth's surface orbital speed is 7.907 km/s
Edited because I can't spell 'Pi'.
Just discovered my g/f can though.
That's what I get for posting before lunch...