A car is negotiating a curved road of radius $R$. The road is banked at an angle $\theta$. The coefficient of friction between the tyres of the car and the road is $\mu_s$ . The maximum safe velocity on this road is :

Question

( A ) $\sqrt{\frac{g}{R^2} \frac{\mu_s + \tan \theta }{1 - \mu_s \tan \theta}}$
( B ) $\sqrt{gR^2 \frac{\mu_s + \tan \theta }{1 - \mu_s \tan \theta}}$
( C ) $\sqrt{gR \frac{\mu_s + \tan \theta }{1 - \mu_s \tan \theta}}$
( D ) $\sqrt{\frac{g}{R} \frac{\mu_s + \tan \theta }{1 - \mu_s \tan \theta}}$