Question

A pendulum of length 40 cm is pulled up so the string attached to the bob is completely horizontal. When released, what is the angular acceleration of the pendulum?

Answer 1

Given data:

* The length of the pendulum is,

$\begin{gathered} L=40\text{ cm} \\ L=0.4\text{ m} \end{gathered}$

* The angle of the pendulum with the y-axis is,

$\theta=90^{\circ}$

Solution:

The angular acceleration of the pendulum in terms of the length is,

$\alpha=\frac{g}{L}\sin (\theta)$

Substituting the known values,

$\begin{gathered} \alpha=\frac{10}{0.4}\sin (90^{\circ}) \\ \alpha=25rads^{-2} \end{gathered}$

Thus, the angular acceleration of the pendulum is 25 radians per second squared.

Hence, the third option is the correct answer.