Dissipation effects in mechanics and thermodynamics

TL;DR

This paper clarifies how dissipation affects energy transfer in mechanics and thermodynamics through examples, emphasizing the role of dissipative forces, heat transfer, and entropy increase in irreversible processes.

Contribution

It provides a detailed analysis of dissipation effects in mechanics and thermodynamics, linking physical examples to the concepts of energy transfer and entropy.

Findings

Dissipative forces lead to internal energy increase or heat transfer.

Dissipation aligns with the second law of thermodynamics.

Impulses and pseudo-works incorporate dissipation in Newton's equations.

Abstract

With the discussion of three examples, we aim at clarifying the concept of energy transfer associated with dissipation in mechanics and in thermodynamics. The dissipation effects due to dissipative forces, such as the friction force between solids or the drag force in motions in fluids, lead to an internal energy increase of the system and/or to a heat transfer to the surrounding. This heat flow is consistent with the second law, which states that the entropy of the universe should increase when those forces are present because of the irreversibility always associated with their actions. As far as mechanics is concerned the effects of the dissipative forces are include in the Newton's equations as impulses and pseudo-works.