Four point masses m, 2m, 3m and 4m are kept at the corners A, B, C and D respectively of a square ABCD of side '$b$'. The moment of inertia of the system about an axis perpendicular to the plane of the square and passing through the point D is

A system of five solid spheres each of mass '$m$' and radius '$r$' are rotating about an axis AA' as shown in figure. Hence the moment of inertia of the system about the axis of rotation AA' is

Two bodies A and B have moment of inertia $I_A$ and $I_B$, and angular momenta $L_A$ and $L_B$ respectively. Both of them have same kinetic energy of rotation. So the ratio $L_A$ to $L_B$ is

The speed with which the earth would have to rotate about its axis so that a person on the equator would weigh $\dfrac{3}{5}$th as much as at present is ($g$ = gravitational acceleration, $R$ = equatorial radius of the earth.)