Question

A simple pendulum is oscillating at 3/4th of a second, where g = 980 cm $se{c}^{-2}$, the length of the pendulum is

• A. 55.85 cm
• B. 48.5 cm
• C. 13.96 cm
• D. 42.2 cm

Answer 1

The correct option is C 13.96 cm

We know,

$T=2\pi \sqrt{\frac{l}{g}}$

$\frac{3}{4}=2\pi \sqrt{\frac{l}{980}}$

$\frac{9}{64{\pi }^2}=\frac{l}{980}$

$l=\frac{980\times 9}{64\times {\pi }^2}$

$l=13.96cm$

Option $\text{C}$ is the correct answer.