Q. A clock which keeps correct time at 20$℃$, is subjected to 40$℃$. If coefficient of linear expansion of the pendulum is $12 \times 10^{- 6}℃^{- 1}$. How much will it gain or lose time?

A) $10.3\ s\ {day}^{- 1}$
B) ${20.6\ s\ day}^{- 1}$
C) ${5\ s\ day}^{- 1}$
D) ${20\min{day}}^{- 1}$
Explanation

(a) Time period, $T = 2\pi\sqrt{\frac{1}{g}}$
$\frac{\mathrm{\Delta}T}{T} = \frac{1}{2}\ \frac{\mathrm{\Delta}l}{l} = \frac{1}{2}\alpha\mathrm{\Delta}\theta$
=$\frac{1}{2} \times 12 \times 10^{- 6}(40 - 20) = 12 \times 10^{- 5}$
$\mathrm{\Delta}T = T \times 12 \times 10^{- 5}$
= $24 \times 60 \times 60 \times 12 \times 10^{- 5}$
= 10.3 s ${day}^{- 1}$

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.