Find the moment of inertia of this disk

1. Apr 12, 2008

Quartz

1. The problem statement, all variables and given/known data

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.

2. Relevant equations
L=IA

3. The attempt at a solution

I spent hours on paper with no end, google "chicken scratch" for proof.

2. Apr 12, 2008

tiny-tim

… one step at a time …

Hi Quartz!

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

First step … what is the parallel-axis theorem?

3. Apr 12, 2008

Quartz

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?

4. Apr 12, 2008

tiny-tim

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.

As rohanprabhu previously pointed out to you:
And if you handed in the work days ago, why did you ask us only 14 hours ago?

5. Apr 12, 2008

Quartz

wans't my original post "04.10.08, 09:32"?
and I got help from my teacher so there.

6. Apr 13, 2008

tiny-tim

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).