# A pendulum made of a uniform wire of cross sectional area A has time period T.

Question:

A pendulum made of a uniform wire of cross sectional area A has time period T. When an additional mass $\mathrm{M}$ is added to its bob, the time period changes to $\mathrm{T}_{\mathrm{M}}$. If the Young's modulus of the material

expansion $(\alpha)$ of the metal of the pendulum shaft are respectively :-

1. $55^{\circ} \mathrm{C} ; \alpha=1.85 \times 10^{-2} /{ }^{\circ} \mathrm{C}$

2. $25^{\circ} \mathrm{C} ; \alpha=1.85 \times 10^{-5} /{ }^{\circ} \mathrm{C}$

3. $60^{\circ} \mathrm{C} ; \alpha=1.85 \times 10^{-4} /{ }^{\circ} \mathrm{C}$

4. $30^{\circ} \mathrm{C} ; \alpha=1.85 \times 10^{-3} /{ }^{\circ} \mathrm{C}$

Correct Option: , 4

Solution: