Which friction is typically greater: static friction or sliding friction?

Static friction is typically greater than sliding friction due to the nature of the forces involved when an object is at rest versus when it is in motion. When an object is stationary, static friction works to prevent it from starting to move. This type of friction arises from the interactions at the microscopic level between the surfaces in contact, which can form interlocking asperities or adhesion points.

Once the object begins to slide, it enters the realm of sliding friction, which is generally lower because the surfaces have already overcome the initial barriers to motion. In sliding friction, the contact points have less time to interlock compared to when the surfaces are stationary. This transition from static to sliding means that the force needed to maintain motion is less than that needed to initiate it.

This difference is why static friction is often characterized as being greater than sliding friction, as it requires more force to overcome the initial resistance of the object being at rest.