What is difference between rolling friction …

Friction is of three types:

1. Static friction: The maximum frictional force present between any two objects when one object just tends to move or slip over the surface of the other object, is called static friction. In case of static friction, the object is actually not moving or sliding over the other object, it only tends to move or slide.
2. Sliding friction: The frictional force present when one object moves slowly or slides over the surface of another object, is known as sliding friction. Thus sliding friction comes into play when an object is sliding over another object. Since sliding friction is smaller than the static friction, it is easier to keep an object moving which is already in motion than to move the same object from rest. That is why, sliding friction is smaller than the static friction.
3. Rolling friction: When an object rolls over the surface of another object, the resistance to its motion is called rolling friction. Rolling friction is much less than sliding friction. Heavy machines can easily be moved from one place to another by placing round logs of wood under them and pushing with the force of hands.