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Physics Bootcamp

Chapter 19 Heat and Temperature

Heating or cooling a physical body causes flow of energy between objects. This flow of energy is called heat. When the energy of bodies change, their physical dimensions and other properties such as temperature also change. We study change in a body using the concept of thermodynamic state and thermodynamic equilibrium.
A macroscopic object contains a large number of atoms and molecules whose motions and interactions give rise to the macroscopically observable properties such as pressure, volume, and temperature. Thermodynamics provides a complete study of the macroscopic properties of a system, primarily based on two laws, viz. the conservation of energy and the irreversible nature of thermal processes.
In principle, it is possible to obtain macroscopic properties from the mechanics of the constituent particles of the system. The subjects of statistical mechanics and kinetic theory provide a more fundamental explanation of the macroscopic thermodynamic properties based on the properties of the microscopic particles of the system. We will study some basic aspects of kinetic theory but statistical mechanics is outside the scope of this book.