Moment of inertia of a body about a given axis is $1.5\, kg\, m^2$ Initially the body is at rest. In order to produce a rotational kinetic energy of $1200\, J$, the angular acceleration of $20\, rad/s^2$ must be applied about the axis of rotation for a duration of ……… $\sec$.

A constant power is supplied to a rotating disc. Angular velocity $\left( \omega  \right)$ of disc varies with number of rotations $(n)$ made by the disc as

A smooth tube of certain mass closed at both ends is rotated in a gravity free space and released. The two balls shown in figure moves towards the ends of the tube and stay there. Then which statement is incorrect about this whole system

  A wheel is rotating with an angular speed of $20\,rad/sec$. It is stopped to rest by applying a constant torque in $4\ s$. If the moment of inertia of the wheel about its axis is $0.20\ kg-m^2$, then the work done by the torque in two seconds will be ………. $J$

Two discs of moment of inertia $I_1$ and $I_2$ and angular speeds ${\omega _1}\,{\rm{and }}{\omega _2}$ are rotating along collinear axes passing through their centre of mass and perpendicular to their plane. If the two are made to rotate together along the same axis the rotational $KE$ of system will be