Rolling friction is smaller than sliding friction, which is not only related to the pressure of one object on another, but also related to the roughness of the contact surface between objects. When friction occurs, it is called harmful friction when the worn friction side is not harmful. For example, chalk rubs on the blackboard, and chalk wears away.
Extended data
reduction method
1, reduce the pressure
2. Reduce the roughness of the contact surface; But this effect is not very good. Change sliding into rolling: Rolling friction is much smaller than sliding friction.
3. Keep the two contact surfaces away from each other:
4. Change sliding friction into rolling friction.
Since the friction occurs between the contact surfaces, it is necessary to "cut the bottom of the pot" and separate their contact surfaces, so as to reduce the friction to a smaller level.
For example, air cushion bearings and hovercraft all use air cushion to reduce friction. For example, a maglev train can separate two contact surfaces from each other to reduce harmful friction.