[填空题]
1.State Newton's law of Gravitation.
2.A geostationary orbit is a special orbit in which satellites follow a circular path and remain above a fixed point above the Earth's surface. A satellite orbits in geostationary orbit at a constant speed of v and orbital radius of R. The mass of the Earth is M.
(1)Show that $\sqrt{\frac{GM}{R}}$
(2)The radius of the satellite's orbit is $4.23 \times10^7\,m$. Use this information to estimate mass of the Earth. M = $\times10^{24}\,kg$
