Question

A pendulum swings through an angle of 30° and describes an arc 8.8 cm in length. Find the length of the pendulum.

Answer 1

Given:
Length of the arc = 8.8 cm
And,
$\theta ={30}^{\circ }$

Now,
Length of the arc =$\frac{2\mathrm{\pi r\theta }}{360}$
$$\begin{gathered} \Rightarrow 8.8=\frac{2\times {\displaystyle \frac{22}{7}}\times r\times 30}{360} \\ \Rightarrow r=\frac{8.8\times 360\times 7}{44\times 30} \\ \Rightarrow r=16.8\mathrm{cm} \end{gathered}$$

∴ Length of the pendulum = 16.8 cm