The period of revolution of a planet around the sun is 8 times that of the earth. If the mean distance of that planet from the sun is r, then mean distance of earth from the sun is

Options

A. `r//2`
B. `2r`
C. `r//4`
D. `4r`

Answer

c

Explanation

`t_(2)=8, r_(2)=r, r_(1)?`
`(T_(2))/(T_(1))=((r_(2))/(r_(1)))^(3//2)`
`(8)^(2//3)=(r_(2))/(r_(1))`
`4=(r_(2))/(r_(1))" "therefore" "r_(1)=(r)/(4).`