# Rolling Motion on Rough Surfaces

• paragchitnis

#### paragchitnis

Friction is necessary to make motion rolling but if the body is already in rolling motion on rough surface without slipping then, is friction necessary to continue the rolling motion ?

## Answers and Replies

Friction is necessary to make motion rolling but if the body is already in rolling motion on rough surface without slipping then, is friction necessary to continue the rolling motion ?
No, not if the surface is horizontal. Once an object is rolling along a horizontal surface, no static friction is required to maintain that rolling motion. (Of course, in 'real life' deformation and rolling friction will slow the object down.)

I am confused on the same thing.
Friction force occurs due to cold locking between the crests and troughs of rough surface and the surface of the body. So without such locking, how could it roll?

Friction force occurs due to cold locking between the crests and troughs of rough surface and the surface of the body. So without such locking, how could it roll?
In an abstract, imaginary situation, the object would just happen to be rotating at a rate where it's circumference surface speed is the same as the speed that the object is moving forwards.

Once the body starts rolling then velocity at point of contact become zero. Hence there is no relative motion between body and surface at that point and hence no friction.