GMm/r^2=mr(2pai/T)^2得
M=4pai^2r^3/GT^2
GMm/R^2=mg
g=GM/R^2=4pai^2r^3/T^2R^2
GMm/R^2=mv^2/R
v=(GM/R)^(1/2)=(4pai^2r^3/RT^2)^(1/2)
GMm/r^2=mr(2pai/T)^2得
M=4pai^2r^3/GT^2
GMm/R^2=mg
g=GM/R^2=4pai^2r^3/T^2R^2
GMm/R^2=mv^2/R
v=(GM/R)^(1/2)=(4pai^2r^3/RT^2)^(1/2)