1 求卫星角速度
ω = 2πn/t
2 地球质量
根据 GMm/(R+h)^2 = m(R+h)ω^2
得 M = (R+h)^3 ω^2 / G = 4π^2n^2 (R+h)^3 / (G*t^2)
3 地球密度
ρ = M/V = 4π^2n^2 (R+h)^3 / (G*t^2) / (4/3 π R^3)