1.2   SYSTEMS, METHODS AND EVENTS:   The grandest abstract of thermodynamics is the universe which is defined to be all that exists in a physical sense. Being infinitely vast, the universe extends way beyond the localized, vanishingly small, spaces of engineering systems and events. The impossibility of dealing with the entirety of the universe mandates a system approach.

NEWTON'S ANALYTIC METHOD:  Newton and his contemporaries believed motions of the planets in the solar system were regular and that by careful study, their behaviors (such as solar ecllipes, etc) could be understood, even predicted. Much interest then, was that motion of a body had two independent components - uniform motion and natural motion.

Newton studied the physical world exhaustively. He made very many insightful conclusions about specific issues. But more important and more lasting was the manner, the approach he took in each and all of his investigations. To this day, the basic method Newton used to contemplate, analyze, and study, forms the basis of the scientific method.

The essence of all methods of science and engineering study follows Newton's approach which was to isolate the system from the surroundings but then to admit influence of the surroundings on system change by means of three constructs: Force, Work and Heat. His technique works well for special investigations. Those understandings and information comprise what is called Newtonian, or Classical Mechanics.

With this talk about systems, boundaries and events, one might wonder why there is change, why do events occur? The answer has to do with energy.

ENERGY: Each of the infinity of relatively tiny pieces of the matter of the universe has energy and some masses have more energy than others. The natural collective tendency of energy among masses is that, in the course of by events, the trend is for all masses ultimately to have the same energy. In infinite time, the belief is that, the entire energy of the universe will be evenly distributed among all masses. Such interior to the system, "energy-leveling," events are called equilibration.

Presently some masses have significant energy and simply for that reason, have a propensity to change of their own accord such that their energy becomes less (yielded to the surrounding) to become closer to the energy of the surroundings. For a system of inert matter to change, energy must be supplied. Energy can be said to belong to either of two realms:

  • Extrinsic Energy is what might be called bulk energy of a system which is extrinsic or outwardly observable. The kinetic energies of two vehicles of equal mass and identical speeds have nothing to do with whether one vehicle is a hybrid and the other an antique. System behaviors of beginning thermodynamics are those of mechanics. Answers to energy interaction and property changes of mechanics are extrinsic. An extrinsic property is independent of the matter of the system. Extrinsic behavior is behavior that can be observed visually in space. It involves mechanical energy, i. e., kinetic energy and potential energy. The systems are bodies, particles, rigid bodies and such.


  • Intrinsic Energy Nitrates, typically fertilizers, are benign compounds in which nitrogen and hydrogen atoms peacefully coexist in the molecular structure. However, when provoked by high temperature, nitrates react explosively.


  • POINT BLANK: calculate the extrinsic energy of a point blank cannon shot.

    HOT SHOT as an intrinsic energy improvement on ordinary cannon shot.

    EVENT:  Every physical analysis or design involves some event. Event is a change that occurs to a system over time. We study four types of events. We will distinguish these events as:

  • null event: The idea, nothing is happening, nothing will happen and in cases, nothing has happened is a common observation or (perspective) objective. A common goal of various engineering designs is to construct something some structure or a light bulb or a car that will perform like-new forever. Non-event seems to mean with nothing happening? No so. Something happens always but slower. The great stonework aquifers, pyramids, cathedrals and pyramids were built as "non-event" structures. Geology has shown there is no permanance - no non-event - but a matter of time. Non-event systems do not have "catalysts." Non-events are studied using "equilibrium" equations. Of course it is true that "something" (aging for example) is always happening.


  • difference event: with these physical scenarios there is some "agent of action." The physical picture includes "a trigger" which will initiate an event that terminates later at some second time (the end or termination time of the event). While system properties might change during the batch event, it is expedient to consider only the initial and terminal system properties. Also we assume the initial and terminal properties to be uniform. With a batch event, two sketches of the system are required corresponding to the initial and final states of the system.


  • rate event: Rate events are transient. The system changes in time. Some examples of steady operation are: an automobile on a test stand running steadily. A person walking on a treadmill - an object being cooled and heated so its temperature does not change - a windmill steadily pumping water into a cattle trough. A bird in hovering flight. System properties of steady, continuing events can vary spatially but do not change with time.


  • transient event: Coffee, once poured into a cup, begins to cool. Its temperature, initially high, by thermal interaction with the surroundings, becomes room temperature. In transient analysis we are interested in the time-wise variation of properties. For example, if a tank containing a gas at high pressure is opened, how much time is required for all of the gas to escape?

  • cyclic event:


  • differential event:


  • cyclic event:


  • increment event:


  • differential event


  • integral event


  • >>>> Section 1.3