Question

A plumb bob is hanging from the ceiling of a car. If the car moves with an acceleration a, what is the angle made by the string with the vertical?

Answer 1

Answer:

$\theta=\tan^{-1}\dfrac{a}{g}$

Explanation:

Here we are assuming that the car is moving in a straight line and is traveling on a smooth surface. When the car is moving with acceleration $a$ the bob moves in the opposite direction with the same acceleration. Gravity is acting on the bob so it is experiencing an acceleration of $g$ downwards.

The angle between the acceleration $a$ and the acceleration due to gravity $g$ is

$\theta=\tan^{-1}\dfrac{a}{g}$.