The distance of two satellites from the surface of the earth `R` and `7R`. There time periods of rotation are in the ratio

Options

A. `1:7`
B. `1:8`
C. `1:49`
D. `1:7^(3//2)`

Answer

B

Explanation

As ` T^2 prop r^3`
Where r = distance from the centre of the earth
` therefore T_1/T_2 = (r_1/r_2)^(3//2)`
Here `r_1 = 2R , r_2 = 8R`
` therefore T_1/T_2 = ((2R)/(8R))^(3//2) = (1)/(4^(3//2)) = 1/8`