Moment of inertia of a disc about an axis which is tangent and parallel to its plane is I . Then the moment of inertia of disc about a tangent, but perpendicular to its plane will be

Options

A. `(3l)/(4)`
B. `(5l)/(6)`
C. `(3l)/(2)`
D. `(6l)/(5)`

Answer

D

Explanation

The moment of inertia of the disc about an axis parallel to its plane is, `l_(t)=l_(d)+MR^(2)`

`rArr" "l=(1)/(4)MR^(2)+MR^(2)`
`=(5)/(4)MR^(2) or MR^(2)=(4l)/(5)`
Now, moment of inertia about a tangent perpendicular to its plane is `l'=(3)/(2)MR^(2)=(3)/(2)xx(4)/(5)l=(6)/(5)l`