It does not depend the area of contact, it doesn't depend on the sliding speed. If you look in more detail than Coulomb friction then $\mu$ does change with the area of contact, a lower area causes lower friction. It does not. The laws of friction written in the books pertain to sliding friction, I feel, where the friction coefficient does not depend on the area of contact.


Answer This is a good question and one which is commonly asked by students when friction is discussed. How does physics predict those characteristics theoretically? Friction (44 of 47) What is Rolling Friction?

Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. The force of friction comes from the surface characteristics of materials that come into contact. The friction force depends on two things: – The normal force (Rn) – The nature of the surfaces involved (µ) Ffriction =µ⋅Rn – The friction force does not depend on the surface area (contact area). It does not. This means that sliding friction does not depend on the size of the contact area. whereas in case of rolling friction, friction factor is very much dependent on the area of contact. Rolling resistance, sometimes called rolling friction or rolling drag, is the resistance that occurs when a round object such as a ball or tire rolls on a flat surface. Carter (1926) and H. Fromm (1927). When the nature of surfaces of the two body if in contact or are same then friction depends on area of contact .in this situation friction is directly proportional to area of contact. Asked by: Elizabeth Stewart Answer Although a larger area of contact between two surfaces would create a larger source of frictional forces, it also reduces the pressure between the two surfaces for a given force holding them together. area is not directly proportional to fŕ(rolling friction) I hope you can understand it if you have any doubt click follow option. Rolling friction does not occur between the tire and the road, but instead is the internal friction of the rubber as it distorts under the load. Classical results for a true frictional contact problem concern the papers by F.W. It is true that wider tires commonly have better traction. The main reason why this is so does not relate to contact patch, however, but to composition. It is caused by the deformation of the object, the deformation of the surface, or both. Friction • The friction force acts in a direction parallel to the area of contact, and opposes the motion or the tendency to move.