Find the moment of inertia of this disk help

In summary, the conversation discusses finding the moment of inertia of a disk with a drilled circular hole using the parallel-axis theorem. The forum users advise the original poster to work on the problem themselves and explain the purpose of the forum. The original poster reveals they have already handed in the homework and received help from their teacher.
  • #1
Quartz
5
0

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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  • #2
… 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:
 
  • #3
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
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?
 
  • #5
wans't my original post "04.10.08, 09:32"?
and I got help from my teacher so there.
 
  • #6
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).
 

1. What is the moment of inertia of a disk?

The moment of inertia of a disk is a measure of its resistance to changes in rotational motion. It is a property of the disk that depends on its mass distribution and the axis of rotation.

2. How do you calculate the moment of inertia of a disk?

The moment of inertia of a disk can be calculated using the formula I = 1/2 * m * r^2, where m is the mass of the disk and r is the radius of the disk. This formula assumes that the mass is evenly distributed throughout the disk and the axis of rotation is perpendicular to the disk's surface.

3. What is the unit of measurement for moment of inertia?

The unit of measurement for moment of inertia is kg * m^2. This unit is derived from the formula I = m * r^2, where m is in kilograms and r is in meters.

4. How does the moment of inertia of a disk affect its rotational motion?

The greater the moment of inertia of a disk, the more resistance it has to changes in rotational motion. This means it will be harder to start or stop spinning, and it will also take more energy to change its rotational speed.

5. How can I use the moment of inertia of a disk in real-world applications?

The moment of inertia of a disk is an important factor in designing and analyzing rotating systems, such as engines, turbines, and flywheels. It can also be used to calculate the rotational kinetic energy of a disk and determine its stability in different rotational motions.

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