The negative sign shows that the gravitational potential energy decreases with increase in distance.
Gravitational potential energy at height h from surface of earth
Uh = – GMm / R + h = mgR / 1 + h / R
Satellite
A heavenly object which revolves around a planet is called a satellite. Natural satellites are those heavenly objects which are not man made and revolve around the earth. Artificial satellites are those neaven objects which are man made and launched for some purposes revolve around the earth.
Time period of satellite
T = 2π √r 3 / GM
= 2π √( R + h) 3 / g [ g = GM / R 2