Find the orbital speed of a satellite in a circular orbit 2640 km above the surface of the Earth. km/s?

Question

Find the orbital speed of a satellite in a circular orbit 2640 km above the surface of the Earth.
km/s

Answer 1

There's a simple formula for circular orbits:

Take the orbital radius = a =orbital altitude+ radius of earth, and divide it by the radius of earth;

q = a/Re = (2640 + 6378)/6378 = 1.3918

The speed is found by

v = 7.905 km/s*sqrt(1/q) = 7.905 km/s * 0.8476 = 6.7 km/s