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A circular disc of radius R and thicknes...

A circular disc of radius R and thickness `R/6` has moment of inertia I about its axis. If it is melted and casted into a solid sphere then what will be its moment of inertia, about its diametric axis?

A

`I/5`

B

`(5I)/12`

C

`I/10`

D

`I`

Text Solution

Verified by Experts

The correct Answer is:
A
Moment of inertia of disc will be `I = (MR^2)/(2)`
Because disc is converted into sphere so radius of sphere will be R’
So, `4/3 pi R.^3 = pi R^2 xx R/6`
`R. = R/2`
So, moment of inertia of sphere will be `I_s = 2/5 M (R/2)^2 = (MR^2)/10`
So, `I_s = I/5`.
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