- #1

TA1068

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## Homework Statement

A 13cm diameter CD has a mass of 25 g.

What is the CD's moment of inertia for rotation about a perpendicular axis through its center?

## Homework Equations

[tex]I = \int r^2 dm[/tex]

and possibly...

Moment of inertia of cylinder or disk, about center = [tex]\frac{1}{2}MR^2[/tex]

## The Attempt at a Solution

I'm given certain values. The mass of the CD is .025 kg and it's radius is .065 m. Other than this, I am very confused. I tried just plugging in (.025)(.065)^2, but that didn't work.

Now I've checked through other threads regarding moment of inertia, but it's not exactly helpful unless I know the very basics. In all honesty, I've never even done integrals before; my calculus class is supposed to parallel what we are doing in physics, but they are doing a very poor job at it. I think I might have the hang of them from looking it up quickly online, though (I'm just a pain, huh?).

I know with such a very limited amount to work with here it can be difficult, but I catch on really quickly (I swear!), but for some reason this is a little tricky. Any pointers in the right direction would be greatly appreciated!