Editing Thermodynamic temperature (section)

== Practical applications for thermodynamic temperature ==
Thermodynamic temperature is useful not only for scientists, it can also be useful for lay-people in many disciplines involving gases. By expressing variables in absolute terms and applying [[Gay-Lussac's law]] of temperature/pressure proportionality, solutions to everyday problems are straightforward; for instance, calculating how a temperature change affects the pressure inside an automobile tire. If the tire has a cold {{Not a typo|gage}}<ref>Regarding the spelling "gage" vs. "gauge" in the context of pressures measured relative to atmospheric pressure, the preferred spelling varies by country and even by industry. Further, both spellings are often used ''within'' a particular industry or country. Industries in British English-speaking countries typically use the spelling "gauge pressure" to distinguish it from the pressure-measuring instrument, which in the U.K., is spelled ''pressure gage''. For the same reason, many of the largest American manufacturers of pressure transducers and instrumentation use the spelling ''{{Not a typo|gage pressure}}'' (the convention used here) in their formal documentation to distinguish it from the instrument, which is spelled ''pressure gauge''.</ref> pressure of 200&nbsp;[[pascal (unit)|kPa]]<!--

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Regarding the spelling of "GAGE" pressure, this is one of two legitimate spellings. Please read the second footnote attached to this paragraph when not in "edit" view. Wikipedia's official policy ([[Wikipedia:Manual of Style]]) is that the spelling convention used by the first major contributors should be retained. This article uses American English spelling conventions.

-->, then its [[absolute pressure]] is 300&nbsp;kPa.<ref>Pressure also must be in absolute terms. The air still in a tire at a [[Pressure measurement#Gauge|{{Not a typo|gage pressure}}]] of 0&nbsp;kPa expands too as it gets hotter. It is not uncommon for engineers to overlook that one must work in terms of absolute pressure when compensating for temperature. For instance, a dominant manufacturer of aircraft tires published a document on temperature-compensating tire pressure, which used {{Not a typo|gage pressure}} in the formula. However, the high {{Not a typo|gage pressures}} involved (180&nbsp;psi; 12.4 bar; 1.24 MPa) means the error would be quite small. With low-pressure automobile tires, where {{Not a typo|gage pressures}} are typically around 2&nbsp;bar (200&nbsp;kPa), failing to adjust to absolute pressure results in a significant error. {{cite web |title=Aircraft tire ratings |publisher=Air Michelin |url=http://airmichelin.com/pdfs/05%20-%20Aircraft%20Tire%20Ratings.pdf |url-status=dead |archive-url=https://web.archive.org/web/20100215151931/http://airmichelin.com/pdfs/05%20-%20Aircraft%20Tire%20Ratings.pdf |archive-date=2010-02-15}}{{bsn|reason=Source lacks metadata|{{subst:DATE}}|date=September 2024}}</ref><ref>A difference of 100&nbsp;kPa is used here instead of the 101.325&nbsp;kPa value of one [[atmosphere (unit)|standard atmosphere]]. In 1982, the [[International Union of Pure and Applied Chemistry]] (IUPAC) recommended that for the purposes of specifying the physical properties of substances, ''the standard pressure'' (atmospheric pressure) should be defined as precisely 100&nbsp;kPa (≈&nbsp;750.062&nbsp;Torr). Besides being a round number, this had a very practical effect: relatively few people live and work at precisely sea level; 100&nbsp;kPa equates to the mean pressure at an altitude of about 112 meters, which is closer to the 194–meter, worldwide median altitude of human habitation. For especially low-pressure or high-accuracy work, true atmospheric pressure must be measured. {{cite book |publisher=International Union of Pure and Applied Chemistry |title=Compendium of Chemical Terminology |url=http://goldbook.iupac.org/S05921.html |chapter=Standard pressure |date=2014 |doi=10.1351/goldbook.S05921 |edition=online 3rd}}</ref> Room temperature ("cold" in tire terms) is 296&nbsp;K. If the tire temperature is 20&nbsp;°C hotter (20&nbsp;kelvins), the solution is calculated as {{sfrac|316 K|296 K}}&nbsp;= 6.8% greater thermodynamic temperature ''and'' absolute pressure; that is, an absolute pressure of 320&nbsp;kPa, which is a {{Not a typo|gage pressure}} of 220&nbsp;kPa.
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