$A$ solid cylinder of mass $20 \ kg$ has length $1 \ m$ and radius $0.2 \ m$. Then its moment of inertia (in $kg \cdot m^2$) about its geometrical axis is

The moments of inertia of a non-uniform circular disc (of mass $M$ and radius $R$) about four mutually perpendicular tangents $AB, BC, CD, DA$ are $I_1, I_2, I_3$ and $I_4$,respectively (the square $ABCD$ circumscribes the circle). The distance of the centre of mass of the disc from its geometrical centre is given by

Four particles,each of mass $m$,are placed at the corners of a square of side $l$. The radius of gyration of the system about an axis passing through the center of the square and perpendicular to its plane is:

The ratio of masses and radii of two circular rings are $1 : 2$ and $2 : 1$ respectively. What is the ratio of their moments of inertia about their central axes?

$A$ thin wire of length $l$ and mass $M$ is bent in the form of a semi-circle. What is its moment of inertia about an axis passing through the ends of the wire?

Four masses are fixed on a massless rod as shown in the figure. The moment of inertia about the axis $PQ$ is about ..... $kg-m^2$.