ABSTRACT
In Chapter 1, certain concepts were arrived at by considering the motion of gas particles in an enclosure. Briey, pressure was found to involve the principle of momentum interchange with the container walls, temperature was associated with the motion of the particles, and density was taken to be a measure of the number of particles per unit volume. This simple analysis followed the history of a single particle, and it was subsequently generalized to all the particles in the enclosure. This type of analysis is representative of a microscopic description of the processes occurring within the boundaries of the dened system, because the history of a single particle was followed in detail. Rather than pursue further the microscopic concept of matter, we shall be concerned with the macroscopic, or average, behavior of the particles composing a system. The macroscopic viewpoint essentially assumes that it is possible to describe the average behavior of these particles at a given time and at some subsequent time after changes have occurred to the system. The
system changes of concern to us in this study are temperature, pressure, density, work, energy, velocity, and position. The power of the macroscopic approach lies in its ability to describe the changes that have occurred to the system without having to detail all the events of the processes involved.
