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

Answer 1

Answer: (A)

Let the angle from the vertical be $\theta$.
The diagram showing the different forces is given
From the figure, $\tan \, \theta=\frac{a}{g}; \theta=\tan^{-1} \frac{a}{g}$