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)`.

Options

A. `R^(3)`
B. `R^(7//2)`
C. `R^(3//2)`
D. `R^(3.75)`

Answer

B

Explanation

`T_(2)//T_(1) = (r_(2)//r_(1))^(3//2) = (6400//36000)^(3//2)`
`T_(2) = 24 xx (6400//36000)^(3//2) = 2` hr