For a given density of planet the orbital period of a satellite near the surface of planet of radius R is proportional to
R1/2
R3/2
R-1/2
R0
T=2πr32√GM
For r≈R
and M=43πR3ρ (ρ = density of planet)
We see that T=√3πρG
i.e., T is independent of R.
Imagine a light planet revolving around a very massive star in a circular orbit of radius R with a period of revolution T. If the gravitational force of attraction between planet and star is proportional to R−52, then T2 is proportional to