For our purposes, we will not be concerned with all the problems of
launching a synchronous satellite into its proper orbit. But you may be
curious why we know that this orbit must be 22,300 miles high. It can be
calculated by using two basic formulas from elementary physics.
From Newton’s Law of Gravitation we know that the velocity, _v_, of a
satellite moving in a circular orbit[5] will be
_v_ = √((_gR_²)/(_r_)),
where _R_ is the radius of the earth, _r_ is the distance from the
center of the earth to the satellite, and _g_ is the acceleration due to
gravity (_see diagram above_).