Question

A simple pendulum is oscillating without damping. When the displacement of the bob is less than maximum, its net acceleration vector $\overrightarrow{a}$ is correctly shown in which of the following options ?

• A.
• B.
• C.
• D.

Answer 1

The correct option is C

If the bob is at the maximum displacement position, then its speed $v=0$ or angular speed $\omega =\frac{v}{r}=0$.

Hence at maximum displacement, the centripetal acceleration of bob $a_n=0$, it will have only tangential acceleration component.


However, when the displacement of the bob is not maximum, then net acceleration $\overrightarrow{a}$ of the bob in position $B$ has two components.

Here,
$a_n=$ radial acceleration (along $BA$)
$a_t=$ tangential acceleration (perpendicular to $BA$)

$\therefore$ Direction of net acceleration $\overrightarrow{a}$ is correctly shown in option (c).