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NEET 2024

Exam: NEET
Year: 2024
Subject: Physics
Chapter: Rotational Motion

NEET 2024 · Physics · Rotational Motion

The moment of inertia of a thin rod about an axis passing through...

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:

Options

A17.5 cm
B20.7 cm
C72.0 cm
D8.5 cm

Correct answer

D. 8.5 cm

Step-by-step solution

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}

$$

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