Lecture 6: Evaluation of Work > Evaluation of Work
Lecture 6: Evaluation of Work > Evaluation of Work
Lecture 6: Evaluation of Work > Evaluation of Work
Simple and Complex Systems
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[FONT=comic sans ms]We now define what we mean by simple systems and complex systems.[/FONT]
[FONT=comic sans ms]The main issue here is the modes of work for a system.[/FONT]
[FONT=comic sans ms]We know that a given system can have any number of modes of work.[/FONT]
[FONT=comic sans ms]Thermodynamics does not put any restriction on this.[/FONT]
[FONT=comic sans ms]We also know that some of these modes of work are two way.[/FONT]
[FONT=comic sans ms]For example, expansion of a gas.[/FONT]
[FONT=comic sans ms]Some others could be one way.[/FONT]
[FONT=comic sans ms]For example, stirring a liquid.[/FONT]
[FONT=comic sans ms]And important number for us is the number of two way work modes.[/FONT]
[FONT=comic sans ms]Let's call this N2w, it represents the number of two way work modes possible for a system.[/FONT]
[FONT=comic sans ms]As an example, let's consider system as a simple gas, say air.[/FONT]
[FONT=comic sans ms]In this particular case the number of two way work modes is one - that is the expansion work mode.[/FONT]
[FONT=comic sans ms]We consider another example in which we take the system as say a dielectric fluid.[/FONT]
[FONT=comic sans ms]In which case the number of two way work modes could be two.[/FONT]
[FONT=comic sans ms]One of them would be expansion-compression.[/FONT]
[FONT=comic sans ms]The second one would be charging-discharging.[/FONT]
[FONT=comic sans ms]Is also possible for a system to have zero number of two way work modes.[/FONT]
[FONT=comic sans ms]For example, if you take an incompressible liquid.[/FONT]
[FONT=comic sans ms]In this case we can say that the number of two way work modes is zero.[/FONT]
[FONT=comic sans ms]Why? No expansion-compression possible, it's not a dielectric so charging discharging is out of question.[/FONT]
[FONT=comic sans ms]Can be stirred, but that is a one way mode of work.[/FONT]
[FONT=comic sans ms]So here we have seen illustrations of systems where you can have a single two way work mode, or system with two two way work modes and even a system with zero two way work modes.[/FONT]
[FONT=comic sans ms]Using this number, we are now going to classify the systems and this classification will be useful later.[/FONT]
[FONT=comic sans ms]For example, if the number of two way work modes is one.[/FONT]
[FONT=comic sans ms]We will called that system a simple system.[/FONT]
[FONT=comic sans ms]If the number of two way work modes is greater than one, two, three, four, we call that system a complex system.[/FONT]
[FONT=comic sans ms]And if it turns out that the number of two way work modes is zero, or the system is constrained such that it can not execute any two way work mode, we will call such a system a rudimentary system.[/FONT]
[FONT=comic sans ms]Rudimentary systems, we will see, will be useful when we consider thermometry and the measurement of temperature.[/FONT]
[FONT=comic sans ms]Most of our illustrations and many of our engineering systems will be simple systems.[/FONT]
[FONT=comic sans ms]And because we come across a large number of different simple systems, it is often possible to classify the simple systems into some subclasses.[/FONT]
[FONT=comic sans ms]For example, a single work mode - we mean a simple system.[/FONT]
[FONT=comic sans ms]But in that, that work mode if the single work mode is that of expansion compression, as that of a gas,[/FONT]
[FONT=comic sans ms]we will call it a simple compressible system - like that of a gas.[/FONT]
[FONT=comic sans ms]If that single work mode is that of electrical charging or discharging as in a rechargeable battery,[/FONT]
[FONT=comic sans ms]we may call it a simple electrical system, Ok?[/FONT]
[FONT=comic sans ms]Take for example a spring, a rubber band.[/FONT]
[FONT=comic sans ms]You can extend it or you can compress it as in case of a spring.[/FONT]
[FONT=comic sans ms]This will be a simple elastic system.[/FONT]
[FONT=comic sans ms]We should notice that only simple systems can be described thus using a single adjective.[/FONT]
[FONT=comic sans ms]Like a simple compressible system, or a simple electrical system, or a simple elastic system.[/FONT]
[FONT=comic sans ms]Complex systems will need more than two, or two or more adjectives.[/FONT]
[FONT=comic sans ms]Thank You.[/FONT]
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