Friction- related to banking of road

[paulrishav93]

Homework Statement

a turn of radius 20m is banked for vehicles going at a speed of 10 m/s ( considering no friction). If the friction co-efficient between road and tyre is 0.3, then the minimum speed of the vehicle is 5x/(11.5)^1/2.

Homework Equations

in case of banking and no friction

tan A= v^2/rg

in case of banking and friction both,

v=[rg(u + tan A)/(1 - u tanA)]^1/2

The Attempt at a Solution

well,
i did not actually understand what the first statement means because if there is friction, then how can one avoid it?

 

[Doc Al]

a turn of radius 20m is banked for vehicles going at a speed of 10 m/s ( considering no friction).

This means that the banking angle of the road is just right so that a vehicle moving at 10 m/s requires no friction to make the turn. (Figure out the angle.)