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