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
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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