Consider the four wheeled vehicle travelling round a track banked at an angle $\theta$ to the horizontal, as shown. Let the conditions be such that when the vehicle is moving with a speed of $v$ there is no sideways force. The forces acting are then weight acting at the centre of gravity $G$ of the vehicle, and the normal reaction $R_1$ and $R_2$ at the wheels. Which of the following values of $\theta$ satisfies the condition for no sideways force?

Question

$\begin{array}{1 1} \tan^{-1} v^2/gr \\ \cot^{-1} v^2/gr \\ \sin^{-1} v^2/gr \\\cos^{-1} v^2/gr \end{array}$