Two speres of radii r and 2r touching each other the force of attraction betweeen them is proportional

Options

A. `R^(2)`
B. `R^(3)`
C. `R^(-3)`
D. `R^(4)`

Answer

D

Explanation

`F=(Gm_(1)m_(2))/(d^(2))=(G.(4)/(3)pi R^(3)rho)/((3R)^(2))xx(4)/(3)pi (2R)^(3)xx rho`
`therefore F prop R^(4)`