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 ........ $m$.

Write the formula for the maximum permissible speed of a vehicle moving on a smooth banked circular track.

$A$ road is $10 \text{ m}$ wide. Its radius of curvature is $50 \text{ m}$. The outer edge is above the inner edge by a distance of $1.5 \text{ m}$. This road is most suited for the velocity $[g = 9.8 \text{ m/s}^2]$: (in $\text{ m/s}$)

$A$ 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? ............... $km/hr$

$A$ railway line is taken round a circular arc of radius $1000 \ m$,and is banked by raising the outer rail $h \ m$ above the inner rail. If the lateral force on the inner rail when a train travels round the curve at $10 \ ms^{-1}$ is equal to the lateral force on the outer rail when the train's speed is $20 \ ms^{-1}$,then the value of $4g \tan \theta$ is equal to: (The distance between the rails is $1.5 \ m$)

Write the formula for the maximum safe speed of a vehicle moving on a smooth curved road of radius $r$ and banking angle $\theta$.