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Physics/Thermodynamics: Continuum & Point Function

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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

Answer
Hello Utkarsh,

I found some websites that should help you:

About continuum idealization:
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

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&cad=rja&uact=8&ved=0CDIQFjAC&url=http%3A%2F%2Fwww.kostic.niu.edu%2F350%2F_350-posted%2F350LecturePPT-Cengel7th%2FChapter_1_lecture.ppt&ei=uJ6oU7neMIqOyATwxYL4Cw&usg=AFQjCNEmYHVeC0jhA7JMrjILDxwTWU0QBg&sig2=Y6OZh-67vq4NYTb_V0lCkA&bvm=bv.69411363,d.aWw
Start the Power Point document and go to page 13

About point function:
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

About 'vary continually':
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

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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.

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