The radius of gyration of a solid sphere of radius $R$ and mass $M$ about its diameter is $K_d$ and that about a tangent of a solid sphere is $K_t$. The ratio of $K_d$ to $K_t$ is

$A$ wheel (rim) of mass $6 \ kg$ and radius $40 \ cm$ is rotating at a rate of $300 \ rpm$. Its moment of inertia is ....... $kg \cdot m^2$.

If $I_1$,$I_2$,and $I_3$ are the moments of inertia of a solid sphere,a hollow cylinder,and a ring,respectively,all having the same mass and radius,which of the following statements is correct?

$A$ uniform thin bar of mass $6 \,kg$ and length $2.4 \,m$ is bent to make an equilateral hexagon. The moment of inertia about an axis passing through the centre of mass and perpendicular to the plane of the hexagon is ...... $\times 10^{-1} \,kg \cdot m^2$.

Four equal masses,$m$ each,are placed at the corners of a square of side length $l$ as shown in the figure. The moment of inertia of the system about an axis passing through $A$ and parallel to $DB$ would be:

$A$ flywheel is constructed such that its entire mass is concentrated at its rim,because......