Hotness, Heat, and Energy

Abstract

The goal of this chapter is to introduce the fundamental quantities and concepts of thermodynamics. We shall motivate the generic laws of thermal physics which we are going to use throughout this book. Constitutive laws will be introduced on an informal basis when needed for getting answers to some special problems. They will be treated in great detail in the following chapters. First, we will discuss hotness and the measurement of temperature. Following this, we will study the properties of heat in some detail. Finally, the relationship between heat and energy has to be dealt with. We shall motivate this relationship by considering the principle of operation of heat engines. Paired with the law of balance of energy, we will be able to address some practical problems which are of general interest to engineers and others concerned with energy problems. First however, let us take a look at what kinds of images and concepts can be formed about heat and hotness from our everyday knowledge of thermal processes.

Thus the production of motive power is due ... not to any real consumption of caloric, but to its transport from a warm body to a cold body.

S. Carnot, 1824