Find the moment of inertia of this disk help

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Homework Help Overview

The discussion revolves around finding the moment of inertia of a flat uniform cylindrical disk with a circular hole drilled into it. The problem includes specific parameters such as the radius of the disk, the mass, and the distance of the hole's center from the disk's center, and it seeks to determine the moment of inertia when rotated about the center of the disk.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants discuss the approach of treating the disk as a solid and then subtracting the hole's contribution to the moment of inertia. There are hints about using the parallel-axis theorem, and some participants express confusion about the theorem itself.

Discussion Status

The discussion is ongoing, with participants exploring different interpretations of the problem and clarifying concepts. Some guidance has been offered regarding the approach to take, but there is no explicit consensus on the solution path yet.

Contextual Notes

There are indications of frustration regarding the timing of the homework submission and the purpose of the forum, with some participants questioning the relevance of seeking help after the assignment has been submitted.

Quartz
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Homework Statement



A curcial part of a piece of machinery starts as a flat uniform cylindrical disk of radius R0 and mass M. It then has a circular hole of radius R1 drilled into it. The hole's center is a distance h from the center of the disk. Find the moment of inertia of this disk (with off-center hole) when rotated about its center, C.

Hint: Consider a solid disk and subtract the hole; use parallel-axis theorem.

Homework Equations


L=IA


The Attempt at a Solution



I spent hours on paper with no end, google "chicken scratch" for proof.
 
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… one step at a time …

Quartz said:
Hint: Consider a solid disk and subtract the hole; use parallel-axis theorem.

Hi Quartz! :smile:

When you're confused, just go one step at a time …

First step … what is the parallel-axis theorem? :smile:
 
Thanks!

wow great help! this forum is the bestest!
so you mean I pretend it's a solid and then subtract the drilled hole?
then with the theorem and some substitution i can get the answer!?
wow great, thanks so much.
too bad i handed this homework in days ago.
but thank god you could explain it so nicely.
Borat: NOT.
my teacher showed it to me, but whatever.

you people, what's the point of this forum?
 
Quartz said:
too bad i handed this homework in days ago.

you people, what's the point of this forum?

The point of this forum is not to do your homework for you.

This is a cooperative forum … we help you to do the work yourself. :smile:

As rohanprabhu previously pointed out to you:
rohanprabhu said:
you need to show some efforts from your side in solving this problem before we can provide you any help with this question.

And if you handed in the work days ago, why did you ask us only 14 hours ago?
 
wans't my original post "04.10.08, 09:32"?
and I got help from my teacher so there.
 
Quartz said:
wans't my original post "04.10.08, 09:32"?

erm … no … your original post, #1 above, was "yesterday" (that's 04.12
08) at 08.45, London time (same day, 03.45 New York time).
 

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