What is the speed of a vehicle moving on a flat and smooth (frictionless) circular path of radius $r$?

$A$ circular freeway entrance and exit are commonly banked to control a moving car at $14 \ m/s$. To design a similar ramp for $28 \ m/s$, one should:

Which component provides the centripetal force for a vehicle moving at an optimum speed on a banked road?

$A$ lorry is moving on a smooth circular path of radius $50 \ m$ with a velocity of $20 \ ms^{-1}$. Then the banking angle of the road is (Acceleration due to gravity $= 10 \ ms^{-2}$)

$A$ road is banked at an angle of $30^o$ to the horizontal for negotiating a curve of radius $10\sqrt{3} \ m$. At what velocity will a car experience no friction while negotiating the curve? ............... $km/hr$

$A$ truck of mass $2000 \,kg$ is moving along a circular path having a radius of curvature $10 \,m$. If the banking angle is $39^{\circ}$, then the maximum permissible speed of the truck is (Acceleration due to gravity $= 10 \,ms^{-2}$, take $\tan 39^{\circ} = 0.81$). (in $\,ms^{-1}$)