The moment of inertia of a solid cylinder of mass 2.5 kg and radius 10 cm about its axis is

The angular velocity of a body changes from $6 \mathrm{rad} \mathrm{s}^{-1}$ to $21 \mathrm{rad} \mathrm{s}^{-1}$ in a time of 1.5 s . If the moment of inertia of the body is $\mathrm{g} \mathrm{m}^2$, then the rate of change of angular momentum of the body is

A circular dise of diameter 0.8 m and mass 4 kg is rolling on a smooth horizontal plane. If 2.56 N m torque is acting on the disc, then its angular acceleration is

A solid sphere and a solid cylinder have same mass and same radius. The ratio of the moment of inertia of the solid sphere about its diameter and the moment of inertia of the solid cylinder about its axis is