Question

A car is moving with a constant speed of $20\, m / s$ in a circular horizontal track of radius $40\, m$ A bob is suspended from the roof of the car by a massless string The angle made by the string with the vertical will be : (Take $g=10 \, m / s ^2$ )

• A. $\frac{\pi}{6}$
• B. $\frac{\pi}{2}$
• C. $\frac{\pi}{4}$
• D. $\frac{\pi}{3}$

Answer 1

The Correct Option is C

$T\sin \theta =\frac{m{l}^2}{R}$
$\tan \theta =\frac{v^2}{Rg}$
$\tan \theta =\frac{20^2}{40\times 10}$
$\tan \theta =1$
$\Rightarrow \theta =\frac{\pi }{4}$