1)why are curved roads banked ?

A car while taking a turn performs circular motion. If the road is level (or horizontal road), the necessary centripetal force is the force of static friction between the car tyres and the road surface.
The friction depends upon the nature of the surfaces in contact and the presence of oil and water on the road. If the friction id inadequate, a speeding car may skid off the road. Since the friction changes with circumstances, it cannot be relied upon to provide the necessary centripetal force. Moreover, friction results in fast wear and tear of the tyres.
To avoid the risk of skidding as well as to reduce the wear and tear of the car tyres, the road surface at a bend is tilted inward, i.e., the outer side of the road is raised above its inner side. This is called banking of road. On a banked road, the resultant of the normal reaction and the gravitational force can act as the necessary centripetal force. Thus, every car can be safely driven on such a banked curve at certain optimum speed, without depending on friction. Hence , a road should be properly banked at a bend. The angle of banking is the angle of inclination of the surface of a banked road at a bend with the horizontal.

To avoid the risk of skildding of vehicles and to reduce the degradation of tyres the road is horizontal, than the necessary centripetal force is of the static friction only

Hi Student,

To avoid the risk of skidding of vehicles and to reduce the degradation of tyres, the curved roads are banked. If the road is horizontal, then the necessary centripetal force is of the static friction only. This friction changes with circumstances like presence of oil on roads etc. Thus this friction becomes inadequate and the vehicle may skid off. So when a road is banked on curved surface then a centripetal force is provided by the component of normal reaction and hence the vehicle or car does not skid off or topple.

Hope it helps you.

Hello aspirant,

f the road is level (or horizontal road), the necessary centripetal force is the force of static friction between the car tyres and the road surface . Thus, every car can be safely driven on such a banked curve at certain optimum speed, without depending on friction. Hence, a road should be properly banked at a bend .

If the road is banked, so that the outer edge is above the inner edge, then a portion of the normal force from the road on the tires points towards the center of the track; this fraction of the normal force can provide enough centripetal force to keep the car moving in a circle.

Hope this helps !