MCQ
A uniform metallic rod rotates about its perpendicular bisector with constant angular speed. If it is heated uniformly to raise its temperature slightly:
  • A
    Its speed of rotation increases.
  • Its speed of rotation decreases.
  • C
    Its speed of rotation remains same.
  • D
    Its speed increases because its moment of inertia increases.

Answer

Correct option: B.
Its speed of rotation decreases.
On heating a uniform metallic rod its length will increase so moment of inertia of rod increased from $I_1$ to
$I_2 ($i.e., $I_1 \text{I}_1\omega_1=\text{I}_2\omega_2)$
$\because\ \text{I}_1<\text{I}_2\Rightarrow\omega_1>\omega_2,$
so angular speed decreases.

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