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# Physics/Thermodynamics: Continuum & Point Function

Question
Dear Sir,

I got stuck when I read this in book: "The continuum idealization allows us to treat properties as point functions and to assume the properties vary continually in space with no jump discontinuities".
What I failed to understand is:-
a) what is a point function? &
b) meaning of 'vary continually' in this context.

Utkarsh

Hello Utkarsh,

http://web.mit.edu/16.unified/www/FALL/thermodynamics/notes/node11.html
Go to Sections 1.2.1 and 1.2.6

http://en.wikipedia.org/wiki/Continuum_mechanics
Section Concept of a continuum

Start the Power Point document and go to page 13

http://chemwiki.ucdavis.edu/Physical_Chemistry/Thermodynamics/State_Functions
Review the entire webpage. I believe their definition of State function and our Point function are equivalent.

https://ecourses.ou.edu/cgi-bin/ebook.cgi?doc=&topic=th&chap_sec=01.3&page=theory
Review the first section.

http://my.safaribooksonline.com/book/engineering/9780123749963/chapter-4dot-the-
Review section 4.5

The key point is to "assume the properties ... [have] no jump discontinuities". The properties, such as pressure or temperature, vary continually or possibly remain constant.

I hope this helps,
Steve

Physics

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#### Steve Johnson

##### Expertise

I would be delighted to help with questions up through the first year of college Physics. Particularly Electricity, Electronics and Newtonian Mechanics (motion, acceleration etc.). I decline questions on relativity and Atomic Physics. I also could discuss the Space Shuttle and space flight in general.

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I have a BS in Physics and an MS in Electrical Engineering. I am retired now. My professional career was in Electrical Engineering with considerable time spent working with accelerometers, gyroscopes and flight dynamics (Physics related topics) while working on the Space Shuttle. I gave formal classroom lessons to technical co-workers periodically over a several year period.

Education/Credentials
BS Physics, North Dakota State University
MS Electrical Engineering, North Dakota State University