$A$ solid sphere of mass $M$ and a disc of mass $M/2$ have the same radius $R$. The ratio of the moment of inertia of the disc about a tangent in its plane to the moment of inertia of the sphere about its tangent is:

Two identical solid spheres each of mass $2\,kg$ and radii $10\,cm$ are fixed at the ends of a light rod. The separation between the centres of the spheres is $40\,cm$. The moment of inertia of the system about an axis perpendicular to the rod passing through its middle point is $........... \times 10^{-3}\,kg\,m^2$.

Three rings each of mass $M$ and radius $R$ are arranged as shown in the figure. The moment of inertia of the system about the axis $YY'$ will be

The moment of inertia of a square loop made of four uniform solid cylinders, each having radius $R$ and length $L$ $(R < L)$, about an axis passing through the midpoints of opposite sides, is (Take the mass of the entire loop as $M$):

Four spheres of diameter $2a$ and mass $M$ are placed with their centres on the four corners of a square of side $b$. The moment of inertia of the system about an axis passing through one of the sides of the square is ..........

The $X$ and $Z$ axes are mutually perpendicular in the plane of a disc,and the $Y$ axis is perpendicular to the plane of the disc. If the moments of inertia of the object about the $X$ and $Y$ axes are $30 \ kg \ m^2$ and $40 \ kg \ m^2$ respectively,then the moment of inertia about the $Z$ axis will be ....... $kg \ m^2$.