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, $\tan \theta =\frac{a}{g};\theta ={\tan }^{-1}\frac{a}{g}$