The moment of inertia of a thin rod about an axis passing through its mid point and perpendicular to the rod is $2400 \mathrm{~g} \mathrm{~cm}^2$. The length of the 400 g rod is nearly:

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Aicharya · Accepted Answer

Moment of inertia of rod $=I=\frac{m \ell^2}{12}$ $\begin{aligned} & \Rightarrow \quad 2400=400 \frac{\ell^2}{12} \ & \Rightarrow \quad 72=\ell^2 \ & \Rightarrow \quad \ell=\sqrt{72}=8.48 \mathrm{~cm} \simeq 8.5 \mathrm{~cm}\end{aligned}$

The moment of inertia of a thin rod about an axis passing through its mid point and perpendicular to the rod…

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