A planet is 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 proportional to `r^(-n),` then `T^(2)` is proportional to

Options

A. `R^(3)`
B. `R^(-3//2)`
C. `R^(-7//2)`
D. `R^(5//2)`

Answer

b

Explanation

`T^(2) prop T^(-n+1) prop R^(1-5//2)`
`T^(2) prop R^(-3//2)`.