The ratio of moments of inertia of two solid spheres of same mass but densities in the ratio `1:8` is

Options

A. `1:4`
B. `4:1`
C. `2:1`
D. `8:1`

Answer

B

Explanation

`M_(1) = M_(2)`
` rho_(1) xx 4/3 piR_(1)^(3) = rho_(2) xx 4/3 piR_(2)^(3)`
`1 xx R_(1)^(3) = 2^(3) xx R_(2)^(3)`
` 1 xx R_(1)^(3) = 2^(3) xxR_(2)^(3)`
`rArr (R_(1))/(R_(2)) = 2 `
` :. (I_(1))/(I_(2)) = 4 `