GmM/R^2=mg
有：GM=g*R^2
F=GmM/(R+h)^2=mg*(R/(R+h))^2
V=√(GM/(R+h))=√{(g*R^2)/(R+h)}
T=2π√{(R+h)^3/GM}=2π√{(R+h)^3/(g*R^2)}