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 the planet and the star is proportational to `R^(-5//2)`, then
(a) `T^(2)` is proportional to `R^(2)`
(b) `T^(2)` is proportional to `R^(7//2)`
(c) `T^(2)` is proportional to `R^(3//3)`
(d) `T^(2)` is proportional to `R^(3.75)`.

Explanation

Here, `F = k R^(-5//2) = mR ((2pi)/(T))^(2)`
or `T^(2) = (4 pi mR)/(k R^(-5//2)) = (4 pi^(2) m)/(k) R^(7//2)`.
Hence, `T^(2) prop R^(7//2)`