Question

A flywheel rotating about a fixed axis has a kinetic energy of $360J$. When its angular speed is $30rad$ $s^{-1}$. The moment of inertia of the wheel about the axis of 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 $0.8kg$ $m^{-2}$

Rotational K.E, $E=\frac{1}{2}I{w}^2$

$360=\frac{1}{2}I(30{)}^2$

$⟹I=.8kg{m}^2$