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Physics · Rotational Dynamics

NEET (UG) 2024 — Question 14

The moment of inertia of a thin rod about an axis passing through its mid point and perpendicular to the rod is 2400 g cm22400 \mathrm{~g} \mathrm{~cm}^{2}. The length of the 400 g rod is nearly:

  1. Option A:

    8.5 cm

    Correct
  2. Option B:

    17.5 cm

  3. Option C:

    20.7 cm

  4. Option D:

    72.0 cm

Answer: A

Step-by-step solution

Moment of inertia of rod⁡=I=mℓ212\operatorname{rod}=I=\frac{m \ell^{2}}{12}

⇒2400=400ℓ212 \Rightarrow \quad 2400=400 \frac{\ell^{2}}{12}

⇒72=ℓ2\Rightarrow \quad 72=\ell^{2}

⇒ℓ=72=8.48 cm≃8.5 cm\Rightarrow \quad \ell=\sqrt{72}=8.48 \mathrm{~cm} \simeq 8.5 \mathrm{~cm}

Answer key and solution verified before publishing.

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Exam
NEET (UG) 2024
Paper
2024 paper
Subject
Physics
Chapter
Rotational Dynamics
Topic
Moment of Inertia

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