ABSTRACT
From physics we know that work occurs when a force acts through a distance. If a mass is elevated in a gravitational field, then a force must act through a distance against the weight of the object being raised, work is done and the body is said to possess an amount of potential energy equal to the work done. If the effect of a force is to accelerate a body, then the body is said to have kinetic energy equal to the work input When two bodies have different temperatures, or degrees of hotness, and the bodies are in contact, then heat is said to flow from the hotter to the colder body. The thermodynamicist selects a portion of matter for study; this is the system. The chosen system can include a small collection of matter, a group of objects, a machine or a stellar system; it can be very large or very small. The system receives or gives up work and heat, and the system collects and stores energy. Both work and heat are transitory forms of energy, i.e., energy that is transferred to or from some material system; on the other hand, energy which is stored, e.g., potential energy or kinetic energy, is a property of the system. A primary goal of thermodynamics is to evaluate and relate work, heat and stored energy of systems.
