📂Physics

Frictional Force and Coefficient of Friction

Definition ¹

Resistance to the motion of an object on a surface or within a medium such as air or water is called the frictional force. In particular, in classical mechanics, the magnitude of the frictional force $F$ is expressed as the product of the coefficient of friction $\mu$ and the normal force $N$ that the object exerts on the contact surface. $$ F = \mu N $$ Friction is broadly divided into two types. When the frictional force is larger than the externally applied force so that the object remains at rest, this is called static friction; when the external force exceeds the frictional force so that the object moves, this is called kinetic friction.

Explanation

In general, the coefficient of static friction $\mu_{s}$ is greater than the coefficient of kinetic friction $\mu_{k}$.

The concept of friction appears as a similar notion across almost all fields where the knowledge of physics and engineering is applied, starting from classical mechanics. For example, in the context of the Black–Scholes model, friction can be viewed as constraints on a series of actions taken when managing assets, which, conceptually, is not very different from resistance in the physical sense.