Coefficient of friction

Static friction: This is the frictional force between two surfaces when they are not moving relative to each other. It prevents objects from starting to slide against each other.

Kinetic friction: This is the frictional force between two surfaces when they are sliding past each other. It opposes the motion of the objects and acts to slow them down.

Rolling friction: This type of friction occurs when an object rolls over a surface, like a ball rolling on the ground. It is generally smaller than static or kinetic friction.