{"id":46003,"date":"2019-10-20T16:24:31","date_gmt":"2019-10-20T15:24:31","guid":{"rendered":"https:\/\/www.thermal-engineering.org\/quest-ce-que-la-formule-de-pression-equation-de-pression-definition\/"},"modified":"2020-02-26T13:37:04","modified_gmt":"2020-02-26T12:37:04","slug":"quest-ce-que-la-formule-de-pression-equation-de-pression-definition","status":"publish","type":"post","link":"https:\/\/www.thermal-engineering.org\/fr\/quest-ce-que-la-formule-de-pression-equation-de-pression-definition\/","title":{"rendered":"Qu&#8217;est-ce que la formule de pression &#8211; \u00c9quation de pression &#8211; D\u00e9finition"},"content":{"rendered":"<div class=\"su-quote su-quote-style-default\">\n<div class=\"su-quote-inner su-clearfix\">Formule de pression &#8211; Equation de pression. La pression est une mesure de la force exerc\u00e9e par unit\u00e9 de surface sur les limites d&#8217;une substance. G\u00e9nie thermique<\/div>\n<\/div>\n<div><\/div>\n<div>\n<div class=\"lgc-column lgc-grid-parent lgc-grid-100 lgc-tablet-grid-100 lgc-mobile-grid-100 lgc-equal-heights  lgc-first lgc-last\">\n<div class=\"inside-grid-column\">\n<h2><span>Formule de pression &#8211; \u00c9quation de pression<\/span><\/h2>\n<p><strong><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Manometer-Pressure-Measurement.png\"><img loading=\"lazy\" class=\"alignright size-medium wp-image-16368 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Manometer-Pressure-Measurement-235x300.png\" alt=\"manom\u00e8tre-pression-mesure\" width=\"235\" height=\"300\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/Manometer-Pressure-Measurement-235x300.png\" \/><\/a><span>La pression<\/span><\/strong><span>\u00a0est une mesure de la\u00a0<\/span><strong><span>force exerc\u00e9e<\/span><\/strong><span>\u00a0par unit\u00e9 de surface sur les limites d&#8217;une substance.\u00a0L&#8217;unit\u00e9 standard de\u00a0<\/span><strong><span>pression<\/span><\/strong><span>\u00a0dans le syst\u00e8me SI est le\u00a0<\/span><strong><span>Newton par m\u00e8tre carr\u00e9 ou pascal (Pa)<\/span><\/strong><span>\u00a0.\u00a0Math\u00e9matiquement (formule de pression):<\/span><\/p>\n<p><strong><span>p = F \/ A<\/span><\/strong><\/p>\n<p><span>o\u00f9<\/span><\/p>\n<ul>\n<li><strong><span>p est la pression<\/span><\/strong><\/li>\n<li><strong><span>F est la force normale<\/span><\/strong><\/li>\n<li><strong><span>A est l&#8217;aire de la fronti\u00e8re<\/span><\/strong><\/li>\n<\/ul>\n<p><span>Pascal est d\u00e9fini comme la force de 1N qui s&#8217;exerce sur la surface unitaire.<\/span><\/p>\n<ul>\n<li><strong><span>1 Pascal = 1 N \/ m\u00a0<\/span><sup><span>2<\/span><\/sup><\/strong><\/li>\n<\/ul>\n<\/div>\n<\/div>\n<div class=\"lgc-column lgc-grid-parent lgc-grid-60 lgc-tablet-grid-60 lgc-mobile-grid-100 lgc-equal-heights  lgc-first\">\n<div class=\"inside-grid-column\"><span>Cependant, pour la plupart des probl\u00e8mes d&#8217;ing\u00e9nierie, il s&#8217;agit d&#8217;une unit\u00e9 assez petite, il est donc pratique de travailler avec des multiples du pascal: le\u00a0<\/span><strong><span>kPa<\/span><\/strong><span>\u00a0, la\u00a0<\/span><strong><span>barre<\/span><\/strong><span>\u00a0et le\u00a0<\/span><strong><span>MPa<\/span><\/strong><span>\u00a0.<\/span><\/p>\n<ul>\n<li><strong><span>1 MPa 10\u00a0<\/span><sup><span>6<\/span><\/sup><span>\u00a0N \/ m\u00a0<\/span><sup><span>2<\/span><\/sup><\/strong><\/li>\n<li><strong><span>1 bar 10\u00a0<\/span><sup><span>5<\/span><\/sup><span>\u00a0N \/ m\u00a0<\/span><sup><span>2<\/span><\/sup><\/strong><\/li>\n<li><strong><span>1 kPa 10\u00a0<\/span><sup><span>3<\/span><\/sup><span>\u00a0N \/ m\u00a0<\/span><sup><span>2<\/span><\/sup><\/strong><\/li>\n<\/ul>\n<p><span>En g\u00e9n\u00e9ral, la pression ou la force exerc\u00e9e par unit\u00e9 de surface sur les limites d&#8217;une substance est caus\u00e9e par les\u00a0<\/span><strong><span>collisions<\/span><\/strong><span>\u00a0des\u00a0<\/span><strong><span>mol\u00e9cules<\/span><\/strong><span>\u00a0de la substance avec les limites du syst\u00e8me.\u00a0Lorsque les mol\u00e9cules frappent les murs, elles exercent des forces qui tentent de pousser les murs vers l&#8217;ext\u00e9rieur.\u00a0Les forces r\u00e9sultant de toutes ces collisions provoquent la\u00a0<\/span><strong><span>pression<\/span><\/strong><span>\u00a0exerc\u00e9e par un syst\u00e8me sur son environnement.\u00a0La pression en tant que\u00a0<\/span><a title=\"Propri\u00e9t\u00e9s \u00e9tendues et intensives\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/thermodynamics\/extensive-and-intensive-properties\/\"><strong><span>variable intensive<\/span><\/strong>\u00a0<\/a><span>est constante dans un syst\u00e8me ferm\u00e9.\u00a0Il n&#8217;est vraiment pertinent que dans les syst\u00e8mes liquides ou gazeux.<\/span><\/p>\n<\/div>\n<\/div>\n<div class=\"lgc-column lgc-grid-parent lgc-grid-40 lgc-tablet-grid-40 lgc-mobile-grid-100 lgc-equal-heights  lgc-last\">\n<div class=\"inside-grid-column\"><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/What-is-Pressure.png\"><img loading=\"lazy\" class=\"aligncenter size-medium wp-image-16371 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/What-is-Pressure-300x129.png\" alt=\"Quelle est la pression\" width=\"300\" height=\"129\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/What-is-Pressure-300x129.png\" \/><\/a><span>[extrait xyz-ihs = &#8220;pression&#8221;]<\/span><\/div>\n<\/div>\n<div class=\"lgc-column lgc-grid-parent lgc-grid-100 lgc-tablet-grid-100 lgc-mobile-grid-100 lgc-equal-heights  lgc-first lgc-last\">\n<div class=\"inside-grid-column\">\n<div class=\"su-spacer\"><\/div>\n<h2><span>Loi du gaz parfait<\/span><\/h2>\n<p><span>Toute \u00e9quation qui relie la pression, la temp\u00e9rature et le volume sp\u00e9cifique d&#8217;une substance est appel\u00e9e une\u00a0<\/span><strong><span>\u00e9quation d&#8217;\u00e9tat<\/span><\/strong><span>\u00a0.\u00a0L&#8217;\u00a0\u00e9quation d&#8217;\u00e9tat la\u00a0plus simple et la\u00a0<\/span><strong><span>plus connue<\/span><\/strong><span>\u00a0pour les substances en phase gazeuse est l&#8217;\u00a0<\/span><strong><span>\u00e9quation<\/span><\/strong><span>\u00a0d&#8217;\u00e9tat du\u00a0<strong>gaz parfait<\/strong>\u00a0.\u00a0\u00c9mile Clapeyron l&#8217;a d\u00e9clar\u00e9 pour la premi\u00e8re fois en 1834 comme une combinaison de la loi empirique de Boyle, de la loi de Charles et de la loi d&#8217;Avogadro.\u00a0Cette \u00e9quation pr\u00e9dit le\u00a0<\/span><strong><span>comportement pvT<\/span><\/strong><span>\u00a0d&#8217;un gaz de fa\u00e7on assez pr\u00e9cise pour les gaz dilu\u00e9s ou \u00e0 basse pression.\u00a0Dans un gaz parfait, les mol\u00e9cules n&#8217;ont pas de volume et n&#8217;interagissent pas.\u00a0Selon la loi du gaz parfait, la pression varie lin\u00e9airement avec la\u00a0<\/span><strong><span>temp\u00e9rature<\/span><\/strong><span>\u00a0et la\u00a0<\/span><strong><span>quantit\u00e9<\/span><\/strong><span>\u00a0, et inversement avec le\u00a0<\/span><strong><span>volume<\/span><\/strong><span>\u00a0.<\/span><\/p>\n<p><strong><i><span>pV = nRT<\/span><\/i><\/strong><\/p>\n<p><span>o\u00f9:<\/span><\/p>\n<ul>\n<li><strong><em><span>p<\/span><\/em><\/strong><span>\u00a0est la<\/span><strong><span>\u00a0pression absolue<\/span><\/strong><span>\u00a0du gaz<\/span><\/li>\n<li><strong><em><span>n<\/span><\/em><\/strong><span>\u00a0est la<\/span><strong><span>\u00a0quantit\u00e9<\/span><\/strong><span>\u00a0de substance<\/span><\/li>\n<li><strong><em><span>T<\/span><\/em><\/strong><span>\u00a0est la<\/span><strong><span>\u00a0temp\u00e9rature absolue<\/span><\/strong><\/li>\n<li><strong><em><span>V<\/span><\/em><\/strong><span>\u00a0est le<\/span><strong><span>\u00a0volume<\/span><\/strong><\/li>\n<li><strong><em><span>R<\/span><\/em>\u00a0<\/strong><span>\u00a0est la<\/span><strong><span>\u00a0constante de gaz<\/span><\/strong><span>\u00a0id\u00e9ale ou universelle,\u00e9gale au produit de la constante de Boltzmann et de la constante d&#8217;Avogadro,<\/span><\/li>\n<\/ul>\n<p><span>Dans cette \u00e9quation, le symbole R est une constante appel\u00e9e constante de\u00a0<\/span><strong><span>gaz universelle<\/span><\/strong><span>\u00a0qui a la m\u00eame valeur pour tous les gaz, \u00e0 savoir\u00a0<\/span><strong><span>R = 8,31 J \/ mol K.<\/span><\/strong><\/p>\n<p><span>La puissance de la loi du gaz parfait r\u00e9side dans sa\u00a0<\/span><strong><span>simplicit\u00e9<\/span><\/strong><span>\u00a0.\u00a0Lorsque\u00a0<\/span><strong><span>deux<\/span><\/strong><span>\u00a0variables thermodynamiques, p, v et T\u00a0<\/span><strong><span>sont\u00a0<\/span><\/strong><strong><span>donn\u00e9es<\/span><\/strong><span>\u00a0, la\u00a0<\/span><strong><span>troisi\u00e8me<\/span><\/strong><span>\u00a0peut\u00a0<\/span><strong><span>\u00eatre facilement trouv\u00e9e<\/span><\/strong><span>.\u00a0Un gaz parfait est d\u00e9fini comme celui dans lequel toutes les collisions entre atomes ou mol\u00e9cules sont parfaitement \u00e9lastiques et o\u00f9 il n&#8217;y a pas de forces d&#8217;attraction intermol\u00e9culaires.\u00a0Un gaz parfait peut \u00eatre visualis\u00e9 comme une collection de sph\u00e8res parfaitement dures qui entrent en collision mais qui, autrement, n&#8217;interagissent pas entre elles.\u00a0En r\u00e9alit\u00e9, aucun gaz r\u00e9el n&#8217;est comme un gaz parfait et donc aucun gaz r\u00e9el ne suit compl\u00e8tement la loi ou l&#8217;\u00e9quation du gaz parfait.\u00a0\u00c0 des temp\u00e9ratures proches d&#8217;un point d&#8217;\u00e9bullition des gaz, une augmentation de la pression provoquera de la condensation et une diminution drastique du volume.\u00a0A des pressions tr\u00e8s \u00e9lev\u00e9es, les forces intermol\u00e9culaires d&#8217;un gaz sont importantes.\u00a0Cependant, la plupart des gaz sont en accord approximatif \u00e0 des pressions et des temp\u00e9ratures sup\u00e9rieures \u00e0 leur point d&#8217;\u00e9bullition.<\/span><\/p>\n<\/div>\n<\/div>\n<div class=\"lgc-column lgc-grid-parent lgc-grid-100 lgc-tablet-grid-100 lgc-mobile-grid-100 lgc-equal-heights  lgc-first lgc-last\">\n<div class=\"inside-grid-column\"><\/div>\n<\/div>\n<\/div>\n<div><\/div>\n<div>\n<p>&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;.<\/p>\n<p>Cet article est bas\u00e9 sur la traduction automatique de l&#8217;article original en anglais. Pour plus d&#8217;informations, voir l&#8217;article en anglais. Pouvez vous nous aider Si vous souhaitez corriger la traduction, envoyez-la \u00e0 l&#8217;adresse: translations@nuclear-power.com ou remplissez le formulaire de traduction en ligne. Nous appr\u00e9cions votre aide, nous mettrons \u00e0 jour la traduction le plus rapidement possible. Merci<\/p>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>Formule de pression &#8211; Equation de pression. La pression est une mesure de la force exerc\u00e9e par unit\u00e9 de surface sur les limites d&#8217;une substance. G\u00e9nie thermique Formule de pression &#8211; \u00c9quation de pression La pression\u00a0est une mesure de la\u00a0force exerc\u00e9e\u00a0par unit\u00e9 de surface sur les limites d&#8217;une substance.\u00a0L&#8217;unit\u00e9 standard de\u00a0pression\u00a0dans le syst\u00e8me SI est &#8230; <a title=\"Qu&#8217;est-ce que la formule de pression &#8211; \u00c9quation de pression &#8211; D\u00e9finition\" class=\"read-more\" href=\"https:\/\/www.thermal-engineering.org\/fr\/quest-ce-que-la-formule-de-pression-equation-de-pression-definition\/\" aria-label=\"En savoir plus sur Qu&#8217;est-ce que la formule de pression &#8211; \u00c9quation de pression &#8211; D\u00e9finition\">Lire la suite<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":[],"categories":[8],"tags":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v15.4 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>Qu&#039;est-ce que la formule de pression - \u00c9quation de pression - D\u00e9finition<\/title>\n<meta name=\"description\" content=\"Formule de pression - Equation de pression. 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