[meteorite-list] Crater excavation question
From: Sam Kimpton <bessel_at_meteoritecentral.com>
Date: Thu Apr 22 09:41:09 2004 Message-ID: <3A86A214.3B136A67_at_europa.com> --------------71B327D527B9D47BF05C51C8 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Thanks Frank; Here is how the American Geological Institute defines adiabatic: "Pertaining to the relationship of pressure and volume when a gas or other fluid is compressed or expanded without either giving off or receiving heat." I think it was the definition above that was throwing me off kilter. Von Nostrand's Scientific Encyclopedia states the following in its entry on thermodynamics: "An enclosure which is such that the equilibrium of system contained within it can only be disturbed by mechanical means is adiabatic, otherwise it is diathermic. It should be noted that Heiken is specifically refering to the decompression of materials in a hypervelocity impact as adiabatic. This sugests that the compressed material ahead of the release wave is being considered as one body defined by a given state or set of values for pressure, volume, and temp- erature and the material behind it is being regarded as another body with a different set of values for these characteristics. An Aidabatic wall between the two allows the two states to exist and undergo changes indepen- dant of one another without direct influence of the state of one on the other. This specifically precludes the transfer of heat energy from the compressed material to the decompressed material but it does not prevent to conversion of energy behind the release wave to thermal energy. moreover Heiken does not specify a change in the specific heat for the two states. He merely says that the energy is increased under compression and released after passage of the decompressional wave as waste heat. I think understand this now! A little bit of thinking, sleep, and careful reading has prevailed once more. Your posting has also helped. Sam Kimpton --------------71B327D527B9D47BF05C51C8 Content-Type: text/html; charset=us-ascii Content-Transfer-Encoding: 7bit <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML> Thanks Frank; <P>Here is how the American Geological Institute defines adiabatic: <BR>"Pertaining to the relationship of pressure and volume when a gas or other <BR>fluid is compressed or expanded without either giving off or receiving heat." <P>I think it was the definition above that was throwing me off kilter. <P>Von Nostrand's Scientific Encyclopedia states the following in its entry on <BR>thermodynamics: "An enclosure which is such that the equilibrium of system <BR>contained within it can only be disturbed by mechanical means is <I>adiabatic</I>, <BR>otherwise it is <I>diathermic</I>. <P>It should be noted that Heiken is specifically refering to the <I>decompression</I> of <BR>materials in a hypervelocity impact as adiabatic. This sugests that the <BR>compressed material ahead of the release wave is being considered as one <BR>body defined by a given <I>state</I> or set of values for pressure, volume, and temp- <BR>erature and the material behind it is being regarded as another body with a <BR>different set of values for these characteristics. An Aidabatic wall <BR>between the two allows the two states to exist and undergo changes indepen- <BR>dant of one another without direct influence of the state of one on the other. <BR>This specifically precludes the transfer of heat energy from the compressed <BR>material to the decompressed material but it does not prevent to conversion <BR>of energy behind the release wave to thermal energy. moreover Heiken does <BR>not specify a change in the specific heat for the two states. He merely says <BR>that the energy is increased under compression and released <I>after</I> passage <BR>of the decompressional wave as <I>waste</I> heat. <P>I think understand this now! A little bit of thinking, sleep, and careful reading <BR>has prevailed once more. <P>Your posting has also helped. <P>Sam Kimpton <BR> </HTML> --------------71B327D527B9D47BF05C51C8-- Received on Sun 11 Feb 2001 09:30:45 AM PST |
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