What is the role of friction in circular motion?

Friction provides the necessary centripetal force for an object to move in a circular path.

In more detail, friction plays a crucial role in circular motion, particularly in scenarios such as a car moving around a bend or a ball rolling in a circular path. In these instances, it is the frictional force between the tyres of the car and the road, or between the ball and the surface it's rolling on, that provides the necessary centripetal force to keep the object moving in a circular path.

Centripetal force is the force that keeps an object moving along a circular path. It acts towards the centre of the circle and is always perpendicular to the motion of the object. Without this force, an object would continue to move in a straight line due to inertia. In the case of circular motion, this force is often provided by friction.

Consider a car moving around a bend. The frictional force between the tyres and the road surface acts towards the centre of the bend. This force provides the necessary centripetal force to keep the car moving in a circular path. If the frictional force were not sufficient, for example if the road were icy or the car were moving too fast, the car would not be able to maintain its circular path and would skid off the road.

Similarly, when a ball is rolled in a circular path, the frictional force between the ball and the surface it's rolling on acts towards the centre of the circle. This force provides the necessary centripetal force to keep the ball moving in a circular path. If the frictional force were not sufficient, the ball would not be able to maintain its circular path and would move off in a straight line.

In conclusion, friction is essential in circular motion as it provides the necessary centripetal force to keep an object moving in a circular path. Without sufficient friction, an object would not be able to maintain its circular path and would move off in a straight line due to inertia.