What is friction?

Friction is defined as a force that resists the relative motion of two surfaces that are in contact with each other. It acts in the opposite direction to the movement or attempted movement of an object. This resistance occurs due to the interactions at the microscopic level between the surfaces.

For example, when you push a box across the floor, friction acts against the direction of the push, making it harder to move the box. This interaction is a fundamental concept in physics that plays a crucial role in everyday activities, from walking to driving, where it prevents slipping.

Understanding friction helps in explaining why certain surfaces may feel rougher or smoother and how they affect the ease with which objects can slide against one another. The other options do not accurately capture the essence of friction; rather they describe different physical concepts.