Question

A plumb line is suspended from a ceiling of a car moving with horizontal acceleration of $a$. What will be the angle of inclination with vertical.

• A. ${\tan }^{-1}\left(a/g\right)$
• B. ${\tan }^{-1}\left(g/a\right)$
• C. ${\cos }^{-1}\left(a/g\right)$
• D. ${\cos }^{-1}\left(g/a\right)$

Answer 1

The correct option is A ${\tan }^{-1}\left(a/g\right)$

When car moves towards right with acceleration a than due to pseudo force the plumb line will tilt in backward direction making an angle $\theta$ with vertical

from the figure$:-$

$\begin{array}{c}\tan \theta =a/g\\ \therefore \theta ={\tan }^{-1}\left(a/g\right)\end{array}$

Hence,

option $\left(A\right)$ is correct answer.