Q1: M.I. of solid sphere, is

ANS:C - Mr²

The term Mr^2 represents the moment of inertia of a point mass m located at a distance r from an axis of rotation. This formula is specifically applicable for a point mass rotating about a fixed axis at a distance �r from the axis. When you have a solid sphere rotating about an axis passing through its center of mass and perpendicular to the surface (its diameter), the mass of the sphere can be considered as a collection of infinitesimally small point masses. The moment of inertia of each of these point masses about the axis of rotation would be mr^2, where m is the mass of the point and r is the perpendicular distance of the point from the axis. For a solid sphere, we integrate this expression over the entire volume of the sphere to find the total moment of inertia. The integral takes into account the contribution of each infinitesimal mass element to the total moment of inertia. The moment of inertia I of a solid sphere about its diameter, obtained through integration, is found to be: I=2/5 ​mr^2