Question

Why rolling friction is less than sliding friction and is really friction is not dependent on the contact area?

Answer 1

Rolling and sliding friction

1. Rolling friction is the friction between the rolling body and the surface.
2. Sliding friction is the resistance that is in between two objects when they are sliding against each other.
3. The friction between the two surfaces is because of the interlocking of the irregularities of the two surfaces. The friction depends on the area of contact between the bodies.
4. If the area of contact between the two surfaces is large then the force of friction is also large.
5. The area of contact is less in rolling than in the case of sliding, so rolling friction is less than the sliding friction.
6. Friction is dependent on the contact area indirectly but the coefficient of friction depends upon the geometry of the objects.