Introduction to Thermodynamics
In this chapter, we delve into thermodynamics, the branch of physics that addresses heat and temperature, focusing on how these entities interact and transform into other forms of energy. Previously, we studied the thermal properties of matter; now we transition to understanding the laws governing thermal energy, detailing how work can be changed into heat, and conversely.
The section traces the historical context in which heat was first perceived as a fluid (caloric) flowing between bodies of different temperatures. This flawed conception was revised, notably by Benjamin Thomson's experiment in 1798, demonstrating that heat is energy arising from work done (e.g., the heat emitted by a drill boring through brass). This shift from viewing heat as a fluid to recognizing it as a form of energy marks a crucial leap in our understanding of thermal processes.
Thermodynamics evolves as a macroscopic science that avoids molecular intricacies, utilizing readily measurable state variables—like pressure, volume, and mass—to capture the state of a system. In doing so, we distinguish it from mechanics, which focuses on particle motion rather than the internal state of a system. The following sections elaborate on essential thermodynamic concepts, including equilibrium, laws, and processes that form the foundation of thermodynamic theory.