What is the primary distinction between static and dynamic friction?

The primary distinction between static and dynamic friction is that static friction applies to stationary objects. Static friction is the force that prevents an object from starting to move when a force is applied. This type of friction acts on objects that are not in motion relative to a surface, thereby providing the resistance needed to overcome inertia and initiate movement.

In contrast, dynamic friction, also known as kinetic friction, applies to objects that are already in motion. It typically has a lower coefficient than static friction, meaning that once an object is in motion, it requires less force to keep it sliding.

The significant aspect is that static friction serves to keep objects at rest, while dynamic friction comes into play once motion has occurred. This fundamental difference is crucial in understanding how forces interact with objects in different states of motion.