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## Homework Statement

We have 3 discs, arranged as the sketch below shows. Find the moment of inertia of the whole system around the axis, passing horizontally through center of the bigger disk:

1. Two smaller disks are fixed and cannot rotate around their axes.

2. Two smaller disks can rotate freely around their axes.

R is the radius of big circle

r is the radius of 2 smaller disks

L is the distance between COM and axes of smaller disks.

M is the mass of bigger disk

m is the mass of 2 smaller disks

[PLAIN]http://www.shrani.si/f/3L/Os/9CLgTJj/rotacija.jpg [Broken]

## Homework Equations

I = (1/2)*m*R^2 ---> moment of inertia for disk

Parallel axis theorem

## The Attempt at a Solution

For the 1st point, my solution would be:

I = (0.5)*M*R^2 + 2*((0.5)*m*r^2 + m*L^2)

However I am not sure about the 2nd one, any hints? Thanks in advcance

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