3 - Oscillating Rings

Take two ferromagnetic rings of different radii and tie them by a string. Connect another string to the larger ring in the same point. Now holding the whole construction by the second string, you can suspend it in the air by a magnet placed above (see linked video). Being held only by these vertical strings, the rings are free to rotate around the vertical axis. Investigate their rotational motion based on the parameters of the system (permeability of the rings, moments of inertia, positions, thickness, etc. ). What happens if you replace the central ring with a disk?