| Basic Thermodynamics ~ J. Pohl © | www.THERMOspokenhere.com (186-E113) |
System is a mental construct, it is an idea, something in your head - not real. System incorporates the aspects of reality each observer believes important. "What, precisely, is the system? What is relevant to the "system events," and howso relevant?" There is rarely agreement. And when there is agreement; it is for trivial, called "classical" situations.
Mental means imaginary. A system is related to reality, but only to the extent of understanding of the observer. Hence the system is imaginary with some imagination needed but grandiose imagination too much. The imagination forms a "construct," a "necessary view" of the physical reality observed. mentally by the observers mind selected for the purpose of mathematical and physical analysis. The system, an image of physical reality, is a tool. Humans select. Either of two basic perspectives is used (or a combination).
Material Perspective: Newton (and others) initiated the science of mechanics. The initial systems of their studies were of the model: BODY. Common cases of the model are projectiles on Earth, planets in their motion, and contained quantities of liquid or gas. Furthermore, these items which we know had size, shape and extent, were nonetheless assumed to have their masses localized at a point.
Spatial Perspective It is hard to tell where it is. Let's assume we know a "box in space" in which its event happens.