Which term refers to the resistance encountered when one surface moves over another?

The term that refers to the resistance encountered when one surface moves over another is friction. Friction is a force that opposes the relative motion between two surfaces in contact. It arises from the interactions between the microscopic roughness of the surfaces and the molecular forces at their interface. There are different types of friction, such as static friction, which acts on objects at rest, and kinetic friction, which applies when the objects are in motion.

Understanding friction is essential in various contexts, such as mechanics, engineering, and everyday activities, because it affects how objects move and how much force is required to start or continue motion. For example, when pushing a box across the floor, it is the friction between the box and the floor that needs to be overcome to initiate movement. Friction is a critical factor in designing machines, vehicles, and even footwear to ensure proper functionality and safety.