Friction is one of the common forces that affect our everyday life and one of the oldest problems studied in physics. An interpretation of its nature is included in all general physics courses, in both high school and college. The desire and need to better understand it guided a long list of scientists who devoted themselves to the study of friction over the past several centuries. In this regard a number of physical and mathematical models have been created to explain different types of friction. Models related to dry friction and its origins can be classified into two groups. The first group includes those that deal with the explanation of static friction, such as the fundamental understanding of friction provided by Charles Augustin de Coulomb in 1781. The second group includes models that explain kinetic friction derived from the Dahl model. Coulomb’s model of the friction force remained dominant in the following centuries, and his contribution continued to be so striking that the term “Coulomb model of friction” can often be found even in modern books. However, an improved understanding of the essence of friction in the past few decades has been a result of better insight into molecular dynamics, which opened a way for the creation of a modern science of friction and wear—tribology.

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