Question

A: Friction between the tyres and the road produces considerable wear and tear. To avoid friction the curved road is given an inclination. R: When the road is banked the horizontal component of the normal reaction provides the necessary centripetal force.

When a car negotiates a curved road, the force of friction between the road and the tyres provides the centripetal force required to keep the car in motion around the curve. A large amount of friction between the tyres and the road produces considerable wear and tear on the tyres. To avoid dependence on friction, the curved road is given an inclination sloping upwards towards the outer circumference. This reduces the wearing of the tyres because the horizontal component of the normal reaction provides the necessary centripetal force. The system of raising the outer edge of a curved road above the inner edge is called the banking of the curved road. When a vehicle negotiates a circular turn of radius r and is banked at an angle θ, the maximum safe velocity is given by vmax = rg tanθ the absence of frictional forces vmax = √rg (μS + tan θ) / (1 - µS tan θ), in the presence of frictional forces.