Static and Dynamic Friction, Rolling Friction Static friction prevents an object from sliding across a surface without external force. The force of stati...
Static friction prevents an object from sliding across a surface without external force. The force of static friction is independent of the normal force and the magnitude of the surface.
Dynamic friction acts when an object is moving across a surface. The force of dynamic friction is proportional to the normal force and the magnitude of the velocity difference between the object and the surface.
Rolling friction is the resistance an object encounters when rolling across a surface. Rolling friction is significantly larger than static friction, and it is caused by the rolling contact patch between the object and the surface.
Examples:
Static friction: A book lying on a table will not move unless pushed or pulled by an external force.
Dynamic friction: A rolling ball will slow down as it moves across a surface.
Rolling friction: A spinning wheel on a surface will experience rolling friction.
Additional Notes:
Static friction is usually much greater than dynamic friction.
Rolling friction is only relevant when the object is rolling across a surface.
Rolling friction is a complex phenomenon that is still not fully understood