What is optimum speed? Write its equation.

(N/A) Optimum speed is the speed at which a vehicle can negotiate a banked curve without relying on friction between the tires and the road surface. At this speed,the necessary centripetal force is provided entirely by the horizontal component of the normal force.
The equation for optimum speed $(v_0)$ on a banked road with banking angle $(\theta)$ and radius of curvature $(r)$ is given by:
$v_0 = \sqrt{rg \tan \theta}$
where:
$r$ = radius of the curve
$g$ = acceleration due to gravity
$\theta$ = angle of banking