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Two discs A and B of same mass M and rad...

Two discs A and B of same mass M and radius R are connected to one another to form single rigid body . Moment of inertia of this attachment about an axis normal to the plane of disc A and passing through its centre is

A

`2MR^2`

B

`3MR^2`

C

`3/2MR^2`

D

`5MR^2`

Text Solution

Verified by Experts

The correct Answer is:
D
Here `I_A=(MR^2)/2`
`I_(AB) =I_(A) +M(2R)^2` from theorem of parallel axis
`I_(AB)=(MR^2)/2+M4R^2=9/2MR^2`
Then `I=I_A+I_(AB)=(MR^2)/2+(9MR^2)/2=5MR^2`
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