Question

A flywheel rotating about a fixed axis has a kinetic energy of $360$ $J$ when its angular speed is $30rad{s}^{-1}$. The moment of inertia of the wheel about the axis rotation is:

• A. $0.6kg$$m^2$
• B. $0.15kg$$m^2$
• C. $0.8kg$$m^2$
• D. $0.75kg$$m^2$

Answer 1

The correct option is C $0.8kg$$m^2$

Given : Angular speed of the flywheel $w=30$ $rad/s$

Rotational kinetic energy $E=360J$

Let the moment of inertia of the fly wheel be $I$

Rotational kinetic energy $E=\frac{1}{2}I{w}^2$

$\therefore$ $360=\frac{1}{2}I\times {30}^2$ $⟹I=0.8$ $kg{m}^2$