Question

A car is moving in a circular horizontal track of radius $10$ m, with a constant speed of a $10$ ms${}^{-1}$. A plump bob is suspended from the roof of the car by a light rigid rod. The angle made by the string with the vertical is (g = $10$ m/s${}^2$)

• A. $0^o$
• B. ${30}^{\circ }$
• C. ${45}^{\circ }$
• D. ${60}^{\circ }$

Answer 1

The correct option is C ${45}^{\circ }$

we have,

$T\sin \theta =\frac{m{v}^2}{r}$

$T\cos \theta =mg$

upon diving both the equations, we get,

$\tan \theta =\frac{v^2}{rg}$

$=\frac{{10}^2}{10\times 10}$

$\tan \theta =1$

$\therefore \theta ={45}^{\circ }$