Q. A blumb bob is hung from the ceiling of a train compartment. The train moves on an inclined track of inclination 30${^\circ}$ with horizontal. Acceleration of train up the plane is $a = 9/2$. The angle which the string supporting the bob makes with normal to the ceiling in equilibrium is
A) $30{^\circ}$
B) $\tan^{- 1}\left( \frac{2}{\sqrt{3}} \right)$
C) $\tan^{- 1}\left( \frac{\sqrt{3}}{2} \right)$
D) $\tan^{- 1}{(2)}$
Explanation
(b) [image:5_image233.emf]
$T\sin{\theta - mg\sin{\theta = ma}}$
$T\sin{\theta = mg\sin{\theta + \frac{mg}{2}\ }}$ …(i)
$T\cos{\theta = mg\cos{\theta\ }}$ …(ii)
Dividing Eq. (i) by Eq. (ii), we get
$\tan{\theta = \frac{2}{\sqrt{3}}}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.