Question

A pendulum swings through an angle of ${30}^o$ and describes an arc length of $11$ cm. Find the length of the pendulum.

Answer 1

Length of any arc is given by

$l=r\theta$

Given, $l=11cm$

and $\theta ={30}^{\circ }=\frac{\pi }{6}$

$⟹r=\frac{11}{22}\times 7\times 6[\because \pi =\frac{22}{7}]$

$=21cm$

Hence, the length of the pendulum is $21cm$.