Question

A uniform metallic rod rotates about its perpendicular bisector with constant angular speed. If it is heated uniformly to raise its temperature slightly, then

• A. its speed of rotation increases
• B. its speed of rotation decreases
• C. its speed of rotation remains same
• D. its speed increases because its moment of inertia Increases

Answer 1

Answer: (B)

its speed of rotation decreases

Answer 2

When a metallic rod is heated it expands. Its moment of inertia $(I)$ about a perpendicular bisector increases. According to law of conservation of angular momentum, its angular speed $(\omega )$ decreases, since $\omega \times \frac{1}{l}$ (according to law of conservation of angular momentum).