Moment of Inertia of a Quarter Disc

AI Thread Summary
The discussion focuses on calculating the Moment of Inertia of a quarter disc with mass M and radius R about an axis through the center and perpendicular to the plane. An initial attempt to find the Moment of Inertia by dividing the value for a full disc by four resulted in an incorrect answer. Participants clarified that while dividing by four is correct, the issue likely stemmed from using the wrong mass. After addressing the mass concern, the original poster confirmed they arrived at the correct solution. The exchange highlights the importance of accurately applying mass in physics calculations.
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1. Find the Moment of Inertia of a Quarter Disc which has mass M and radius R about the axis passing through the center (of original disc) and perpendicular to the plane.

2. The attempt at a solution
I found the Moment of Inertia (I) of a disc about the axis passing through the center, perpendicular to the plane and divided by 4. It gave the wrong answer.

So, please tell me that why dividing by 4 is giving me the wrong answer for the quarter disc.

Also, a hint of how should I start the problem.
 
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Dividing by 4 is correct. Did you use the correct mass? (I suspect that's the problem.)
 
Doc Al said:
Dividing by 4 is correct. Did you use the correct mass? (I suspect that's the problem.)

Yes, I got it correct now.


Thanks
 

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