If a disc of mass $M$ and radius $R$ rotates with an angular acceleration $a$, the torque acting on the disc is

$A$ solid disc has a diameter of $0.5 \ m$ and a mass of $16 \ kg$. What torque must be applied to increase its angular velocity from $0$ to $120 \ rpm$ in $8 \ s$?

$A$ hollow sphere of mass $1 \,kg$ and radius $10 \,cm$ is free to rotate about its diameter. If a force of $30 \,N$ is applied tangentially to it,its angular acceleration is (in $rad/s^2$):

$A$ solid cylinder of mass $50\, kg$ and radius $0.5\, m$ is free to rotate about a horizontal axis. $A$ massless string is wound around the cylinder with one end attached to it and the other hanging freely. The tension in the string required to produce an angular acceleration of $2\, \text{revolutions } s^{-2}$ is ...... $N$.

To maintain a rotor at a uniform angular speed of $100\, rad\, s^{-1}$,an engine needs to transmit a torque of $100\, Nm$. The power of the engine is

$A$ light rope is wound around a hollow cylinder of mass $5\,kg$ and radius $70\,cm$. The rope is pulled with a force of $52.5\,N$. The angular acceleration of the cylinder will be.....$rad\,s^{-2}$.