This new edition is designed for a one semester introductory course in thermodynamics, either in mechanical or aerospace engineering, or in an engineering science program. The book contains a section on the geometry of curves and surfaces, in order to review those parts of calculus that are needed in thermodynamics for discussing the thermodynamic equations of state of simple compressible substances, and their approximation by linear interpolation. It presents the First Law of Thermodynamics as an equation for the time rate of change of system energy, the same way that Newton’s Law of Motion, an equation for the time rate of change of system momentum, is presented in Dynamics, and presents the Second Law mathematically as a lower bound for the time rate of change of system entropy. Moreover, this emphasis illustrates the importance of thermodynamics to the study of heat transfer and fluid mechanics. These laws and the associated new thermodynamic properties, energy and entropy, are introduced with extended motivating discussions rather than as abstract postulates, and connections are made with kinetic theory. Thermodynamic properties of the vaporizable liquids- condensible gases needed for the solution of practical thermodynamic problems (e.g. water and a typical refrigerant) are presented in a unique tabular format that is both simple to understand and easy to use. All theoretical discussions throughout the book are accompanied by worked examples illustrating their use in practical devices. These examples of the solution of various kinds of thermodynamic problems are all structured in exactly the same way in order to make, as a result of the repetition, the solution of new problems easier for students to follow, and ultimately, to produce themselves. Many additional problems are provided, half of them with answers, for students to do on their own.