ABSTRACT
This chapter presents a new area of physics titled as thermal physics. Although heat as a concept related to hot objects is an old concept, the essence of thermal physics started to become well defined only at the turn of the nineteenth century when new notions and physical quantities relevant to heat were developed. Among these were internal energy, entropy, and enthalpy. Heat is now commonly perceived as a form of random energy that is transferred from hot objects to cold objects when these objects are in thermal contact. This perception came as a result of pioneering experiments by Joule who demonstrated in a quantitative manner the equivalence between heat and energy. The exchange of heat from a hot object to a cold one ceases when the two objects get to a state of equilibrium. Work on this field leads to a formulation of two laws of thermal physics known as the first and second laws of thermodynamics. For the sake of brevity, this chapter will be limited to the discussion of heat with a special focus on expansion of solids.
