The speed of a car is increased by $10\%$. If the angle of banking remains constant,the radius of the turn must be changed from $20 \ m$ to ........ $m$.

$Assertion$ : There is a stage when frictional force is not needed at all to provide the necessary centripetal force on a banked road.
$Reason$ : On a banked road,due to its inclination the vehicle tends to remain inwards without any chances of skidding.

Roads are banked on curves so that

On a railway curve,the outside rail is laid higher than the inside one so that the resultant force exerted on the wheels of the rail car by the tops of the rails will:

$A$ car travels on a circular racetrack of radius $50 \text{ m}$, which is banked at an angle $\theta$. If the car travels at a speed $10 \text{ ms}^{-1}$, then the wear and tear on its tyres is minimum. Taking the acceleration due to gravity to be $10 \text{ ms}^{-2}$, the value of $\theta$ is:

$A$ 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 $= 10 \ ms^{-2}$)