Moment of Inertia of a Fly Wheel – Rankers Physics

Moment of Inertia of a Fly Wheel

A fly wheel rotating about fixed axis has a kinetic energy of $360 \text{ joule}$ when its angular speed is $30 \text{ rad/sec}$. The moment of inertia of the wheel about the axis of rotation is: (1990)

$0.6 \text{ kgm}^2$
$0.15 \text{ kgm}^2$
$0.8 \text{ kgm}^2$
$0.75 \text{ kgm}^2$

Solution:

The formula for rotational kinetic energy is $K = \frac{1}{2} I \omega^2$. Substituting the given values, $360 = \frac{1}{2} I (30)^2 = 450 I$. Solving for $I$ gives $I = \frac{360}{450} = 0.8 \text{ kgm}^2$.

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