13.2.3—Circular orbits in gravitational fields by relating the gravitational force

For a circular orbit, gravitational attraction provides F=mv²/r, so the orbital speed satisfies GMm/r²=mv²/r.

Use the distance r from the attracting body’s centre and remember that gravity is inward while velocity is tangential.

A lower circular orbit has greater speed because v=√(GM/r) increases as r decreases.

Gravity is not absent in orbit; an orbiting object is continuously falling while its tangential motion carries it around.