Introduction + Point Mass + Ring
There are two particles of mass m and 2m that are connected by a rigid, thin, massless rod AB of length L. There is another thin, massless rod CD of length 2L, that connects two other particles of mass 2m and 3m. The two rods are welded together at a point O, to form a single rigid body. The point O is chosen such that , and . Let the moment of inertia of the system about an axis passing through O, and perpendicular to the plane of the two rods be I, find I.
Two particles of mass m and 2m are connected by a thin, rigid massless rod AB of length 2l. There is another right-angled, L-shaped rod CD that connects two other particles of mass m and 2m. Each arm of the L-shaped rod has a length l. As shown in the figure, the two arms of the L-shaped rod is placed perpendicular to AB and welded together with it at its mid-point O to form a rigid body. This rigid body is kept in position such that rod AB is horizontal and the two arms of the L-shaped rod each make an angle of 45o with the vertical. If the moment of inertia of the system about the vertical axis passing through O is I, find I.