What is rolling?
Rolling friction is a resistance force acting to slow down the movement of the ball, cylinder or wheel that moves in a straight line over the surface level. This force is largely the result of the properties of the material of the object and the surface with which it is in contact. Deformations or irregularities in an object or surface are important factors that affect the size of the rolling friction, as well as the contact area between the two. When the object is at rest in contact with the surface, these irregularities catch each other and resist movement. This is static friction.
The amount of force applied to the object to start movement must be sufficient to overcome static friction. In order to stay in motion, the object must overcome the resistance caused by inconsistency. This resistance is kinetic friction.
When the materials consisting of object and surface are relatively rigid, there is only a low deformity in the shape of an object or the elasticity of the surface. In this case, the primary factors determining rolling friction are static or kineticé friction and molecular friction. Molecular friction is not a product of surface irregularities, but chemical binding and electrical interactions.
smaller materials could allow the object or surface to deform shape or elastic due to their interaction. An object such as a tire or basketball may deform as it rolls. Changing the shape of a soft object moving on a hard surface increases the area of contact with the surface. Kinetic friction increases and the size of the rolling friction also increases.
If the surface over which the object is a path, soft or elastic, the object immerses into the surface and must push through the path. This is Known as a plowing effect and is the main part of the rolling friction in these circumstances. The resistance force is not evenly distributed into the contact with the object. The surface deformation is the largest in the direction of the object movement. In fact, this increases static friction and this friction.
If the object and the surface are elastic, the interaction between them is relative and can be manipulated for the desired result. Deforming the shape of the object can increase the surface elasticity. It is often easier to drive a car with soft dirt if, for example, the tires of the car are less than fully inflated.