Two discs have same mass and thickness. Their materials are of densities `pi` and `pi_(2)`. The ratio of their moment of inertia about central axis will be

Options

A. `pi_(1):pi_(2)`
B. `pi_(1)pi_(2):1`
C. `1:pi_(1)pi_(2)`
D. `pi_(2):pi_(1)`

Answer

D

Explanation

`M=piR^(2)rho, M` and `t` same `R^(2)rho=`constant
or `R^(2)prop1//rho`
Again `I=l1/2MR^(2)` or `IpropR^(2)` or `lprop1/(rho)` or `I prop1/(rho)`
`:. (I_(1))/(I_(2))=(P_(2))/(P_(1))`