{"id":52793,"date":"2020-02-25T20:07:14","date_gmt":"2020-02-25T19:07:14","guid":{"rendered":"https:\/\/www.thermal-engineering.org\/quest-ce-que-lenergie-cinetique-definition\/"},"modified":"2020-02-25T20:07:14","modified_gmt":"2020-02-25T19:07:14","slug":"quest-ce-que-lenergie-cinetique-definition","status":"publish","type":"post","link":"https:\/\/www.thermal-engineering.org\/fr\/quest-ce-que-lenergie-cinetique-definition\/","title":{"rendered":"Qu&#8217;est-ce que l&#8217;\u00e9nergie cin\u00e9tique &#8211; D\u00e9finition"},"content":{"rendered":"<p><span>L&#8217;\u00e9nergie cin\u00e9tique, K, est d\u00e9finie comme l&#8217;\u00e9nergie stock\u00e9e dans un objet en raison de son mouvement. <\/span><span>Il est appel\u00e9 \u00e9nergie cin\u00e9tique, du mot grec kinetikos &#8211; mouvement.\u00a0<\/span><span>G\u00e9nie thermique<\/span><\/p>\n<p>&nbsp;<\/p>\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>Qu&#8217;est-ce que l&#8217;\u00e9nergie cin\u00e9tique<\/span><\/h2>\n<p><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/conservartion-of-mechanical-energy-pendulum.png\"><img loading=\"lazy\" class=\"alignright size-full wp-image-15713 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/conservartion-of-mechanical-energy-pendulum.png\" alt=\"pendule \u00e0 conservation d'\u00e9nergie m\u00e9canique\" width=\"282\" height=\"214\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/conservartion-of-mechanical-energy-pendulum.png\" \/><\/a><\/p>\n<p><strong><span>L&#8217;\u00e9nergie cin\u00e9tique,\u00a0<\/span><em><span>K<\/span><\/em><\/strong><span>\u00a0, est d\u00e9finie comme l&#8217;\u00e9nergie stock\u00e9e dans un objet en raison de son mouvement.\u00a0Un objet en mouvement a la capacit\u00e9 de travailler et peut donc \u00eatre consid\u00e9r\u00e9 comme ayant de l&#8217;\u00e9nergie.\u00a0On l&#8217;appelle \u00e9nergie cin\u00e9tique, du mot grec kinetikos, qui signifie \u00abmouvement\u00bb.<\/span><\/p>\n<p><span>L&#8217;\u00a0<\/span><strong><span>\u00e9nergie cin\u00e9tique<\/span><\/strong><span>\u00a0d\u00e9pend de la vitesse d&#8217;un objet et est la capacit\u00e9 d&#8217;un objet en mouvement \u00e0 travailler sur d&#8217;autres objets lorsqu&#8217;il entre en collision avec eux.\u00a0D&#8217;autre part, l&#8217;\u00e9nergie cin\u00e9tique d&#8217;un objet repr\u00e9sente la quantit\u00e9 d&#8217;\u00e9nergie n\u00e9cessaire pour augmenter la vitesse de l&#8217;objet du repos (v = 0) \u00e0 sa vitesse finale.\u00a0L&#8217;\u00e9nergie cin\u00e9tique d\u00e9pend \u00e9galement lin\u00e9airement de la masse, qui est une mesure num\u00e9rique de l&#8217;\u00a0<\/span><strong><span>inertie<\/span><\/strong><span>\u00a0d&#8217;un objet et la mesure de la r\u00e9sistance d&#8217;un objet \u00e0 l&#8217;acc\u00e9l\u00e9ration lorsqu&#8217;une force est appliqu\u00e9e.<\/span><\/p>\n<p><span>Nous d\u00e9finissons la quantit\u00e9:<\/span><\/p>\n<p><em><strong><span>K = \u00bd mv\u00a0<\/span><sup><span>2<\/span><\/sup><\/strong><\/em><\/p>\n<p><span>\u00eatre l&#8217;\u00a0<\/span><strong><span>\u00e9nergie cin\u00e9tique de translation<\/span><\/strong><span>\u00a0de l&#8217;objet.\u00a0Il faut l&#8217;ajouter, on l&#8217;appelle l&#8217;\u00e9nergie cin\u00e9tique \u00abtranslationnelle\u00bb pour la distinguer de l&#8217;\u00e9nergie cin\u00e9tique rotationnelle.<\/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\">\n<div class=\"su-spacer\"><\/div>\n<h2><span>Conservation de l&#8217;\u00e9nergie m\u00e9canique<\/span><\/h2>\n<p><span>Le principe de la\u00a0<\/span><strong><span>conservation de l&#8217;\u00e9nergie m\u00e9canique a d&#8217;abord<\/span><\/strong><span>\u00a0\u00e9t\u00e9 \u00e9nonc\u00e9:<\/span><\/p>\n<p><em><strong><span>L&#8217;\u00e9nergie m\u00e9canique totale<\/span><\/strong><span>\u00a0(d\u00e9finie comme la somme de ses \u00e9nergies potentielles et cin\u00e9tiques) d&#8217;une particule sur laquelle agissent uniquement les forces conservatrices\u00a0<\/span><strong><span>est constante<\/span><\/strong><span>\u00a0.<\/span><\/em><\/p>\n<p><strong><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/conservartion-of-mechanical-energy-example.png\"><img loading=\"lazy\" class=\"alignright size-full wp-image-15711 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/conservartion-of-mechanical-energy-example.png\" alt=\"exemple de conservation de l'\u00e9nergie m\u00e9canique\" width=\"194\" height=\"172\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/conservartion-of-mechanical-energy-example.png\" \/><\/a><\/strong><\/p>\n<p><span>Voir aussi:\u00a0<\/span><a title=\"Conservation de l'\u00e9nergie m\u00e9canique\" href=\"https:\/\/www.nuclear-power.com\/laws-of-conservation\/law-of-conservation-of-energy\/conservation-of-mechanical-energy\/\"><span>Conservation de l&#8217;\u00e9nergie m\u00e9canique<\/span><\/a><\/p>\n<p><strong><span>Un syst\u00e8me isol\u00e9<\/span><\/strong><span>\u00a0est un\u00a0<strong>syst\u00e8me<\/strong>\u00a0dans lequel\u00a0<\/span><strong><span>aucune force externe ne<\/span><\/strong><span>\u00a0provoque de changements d&#8217;\u00e9nergie.\u00a0Si seules\u00a0<\/span><strong><span>les forces conservatrices<\/span><\/strong><span>\u00a0agissent sur un objet et\u00a0<\/span><strong><span>U<\/span><\/strong><span>\u00a0est la\u00a0fonction d&#8217;\u00a0<\/span><strong><span>\u00e9nergie potentielle<\/span><\/strong><span>\u00a0pour la force conservatrice totale, alors<\/span><\/p>\n<p><em><strong><span>E\u00a0<\/span><\/strong><strong><sub><span>mech<\/span><\/sub><\/strong><strong><span>\u00a0= U + K<\/span><\/strong><\/em><\/p>\n<p><strong><span>L&#8217;\u00e9nergie potentielle,\u00a0<\/span><em><span>U<\/span><\/em><\/strong><span>\u00a0, d\u00e9pend de la position d&#8217;un objet soumis \u00e0 une force conservatrice.<\/span><\/p>\n<p><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/potential-energy-equation.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-15710 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/potential-energy-equation.png\" alt=\"\u00e9quation-\u00e9nergie-potentielle\" width=\"176\" height=\"71\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/potential-energy-equation.png\" \/><\/a><\/p>\n<p><span>Elle est d\u00e9finie comme la capacit\u00e9 de l&#8217;objet \u00e0 travailler et est augment\u00e9e lorsque l&#8217;objet est d\u00e9plac\u00e9 dans la direction oppos\u00e9e \u00e0 la direction de la force.<\/span><\/p>\n<p><strong><span>L&#8217;\u00e9nergie potentielle<\/span><\/strong><span>\u00a0associ\u00e9e \u00e0 un syst\u00e8me compos\u00e9 de la Terre et d&#8217;une particule voisine est\u00a0\u00a0<\/span><strong><span>l&#8217;\u00e9nergie potentielle gravitationnelle<\/span><\/strong><span>\u00a0.<\/span><\/p>\n<p><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/gravitational-potential-energy-equation.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-15712 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/gravitational-potential-energy-equation.png\" alt=\"gravitationnel-potentiel-\u00e9nergie-\u00e9quation\" width=\"256\" height=\"45\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/gravitational-potential-energy-equation.png\" \/><\/a><\/p>\n<p><strong><span>L&#8217;\u00e9nergie cin\u00e9tique,\u00a0<\/span><em><span>K<\/span><\/em><\/strong><span>\u00a0, d\u00e9pend de la vitesse d&#8217;un objet et est la capacit\u00e9 d&#8217;un objet en mouvement \u00e0 travailler sur d&#8217;autres objets lorsqu&#8217;il entre en collision avec eux.<\/span><\/p>\n<p><em><strong><span>\u00a0K = \u00bd mv\u00a0<\/span><sup><span>2<\/span><\/sup><\/strong><\/em><\/p>\n<p><span>La d\u00e9finition mentionn\u00e9e ci-dessus (\u00a0<\/span><strong><span>E\u00a0<\/span><\/strong><strong><sub><span>mech<\/span><\/sub><\/strong><strong><span>\u00a0= U + K<\/span><\/strong><span>\u00a0) suppose que le syst\u00e8me est\u00a0<\/span><strong><span>exempt de frottement<\/span><\/strong><span>\u00a0et d&#8217;autres\u00a0<\/span><a title=\"Conservateur - Forces non conservatrices\" href=\"https:\/\/www.nuclear-power.com\/laws-of-conservation\/law-of-conservation-of-energy\/conservative-nonconservative-forces\/\"><strong><span>forces non conservatrices<\/span><\/strong><\/a><span>\u00a0.\u00a0La diff\u00e9rence entre une force conservatrice et une force non conservatrice est que lorsqu&#8217;une force conservatrice d\u00e9place un objet d&#8217;un point \u00e0 un autre, le travail effectu\u00e9 par la force conservatrice est ind\u00e9pendant du chemin.<\/span><\/p>\n<p><span>Dans toute situation r\u00e9elle, des\u00a0<\/span><strong><span>forces de friction<\/span><\/strong><span>\u00a0et d&#8217;autres\u00a0<strong>forces<\/strong>\u00a0non conservatrices sont pr\u00e9sentes, mais dans de nombreux cas, leurs effets sur le syst\u00e8me sont si faibles que le principe de\u00a0<\/span><strong><span>conservation de l&#8217;\u00e9nergie m\u00e9canique<\/span><\/strong><span>\u00a0peut \u00eatre utilis\u00e9 comme une approximation juste.\u00a0Par exemple, la force de friction est une force non conservatrice, car elle agit pour r\u00e9duire l&#8217;\u00e9nergie m\u00e9canique dans un syst\u00e8me.<\/span><\/p>\n<p><span>Notez que les forces non conservatrices ne r\u00e9duisent pas toujours l&#8217;\u00e9nergie m\u00e9canique.\u00a0Une force non conservatrice modifie l&#8217;\u00e9nergie m\u00e9canique, il existe des forces qui augmentent l&#8217;\u00e9nergie m\u00e9canique totale, comme la force fournie par un moteur ou un moteur, est \u00e9galement une force non conservatrice.<\/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\">\n<div class=\"su-spacer\"><\/div>\n<h2><span>Bloc glissant sur une pente inclin\u00e9e sans friction<\/span><\/h2>\n<p><span>Le bloc de 1 kg commence \u00e0 une hauteur H (disons 1 m) au-dessus du sol, avec\u00a0<\/span><strong><span>une \u00e9nergie potentielle\u00a0<\/span><\/strong><strong><span>mgH<\/span><\/strong><span>\u00a0et\u00a0<\/span><strong><span>une \u00e9nergie cin\u00e9tique<\/span><\/strong><span>\u00a0\u00e9gale \u00e0 0. Il glisse vers le sol (sans frottement) et arrive sans \u00e9nergie potentielle et \u00e9nergie cin\u00e9tique\u00a0<\/span><strong><span>K = \u00bd mv\u00a0<\/span><sup><span>2<\/span><\/sup><\/strong><span>\u00a0.\u00a0Calculez la vitesse du bloc au sol et son \u00e9nergie cin\u00e9tique.<\/span><\/p>\n<p><strong><em><span>E\u00a0<\/span><\/em><\/strong><strong><em><sub><span>mech<\/span><\/sub><\/em><\/strong><strong><em><span>\u00a0= U + K = const<\/span><\/em><\/strong><\/p>\n<p><strong><em><span>=&gt; \u00bd mv\u00a0<\/span><\/em><\/strong><strong><em><sup><span>2<\/span><\/sup><\/em><\/strong><strong><em><span>\u00a0= mgH<\/span><\/em><\/strong><\/p>\n<p><strong><em><span>=&gt; v = \u221a2gH = 4,43 m \/ s<\/span><\/em><\/strong><\/p>\n<p><strong><em><span>=&gt; K\u00a0<\/span><\/em><\/strong><strong><em><sub><span>2<\/span><\/sub><\/em><\/strong><strong><em><span>\u00a0= \u00bd x 1 kg x (4,43 m \/ s)\u00a0<\/span><\/em><\/strong><strong><em><sup><span>2<\/span><\/sup><\/em><\/strong><strong><em><span>\u00a0= 19,62 kg.m\u00a0<\/span><\/em><\/strong><strong><em><sup><span>2<\/span><\/sup><\/em><\/strong><strong><em><span>\u00a0.s\u00a0<\/span><\/em><\/strong><strong><em><sup><span>-2<\/span><\/sup><\/em><\/strong><strong><em><span>\u00a0= 19,62 J<\/span><\/em><\/strong><\/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\">\n<div class=\"su-spacer\"><\/div>\n<h2><span>Pendule<\/span><\/h2>\n<p><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/conservartion-of-mechanical-energy-pendulum.png\"><img loading=\"lazy\" class=\"alignright size-full wp-image-15713 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/conservartion-of-mechanical-energy-pendulum.png\" alt=\"pendule \u00e0 conservation d'\u00e9nergie m\u00e9canique\" width=\"282\" height=\"214\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/conservartion-of-mechanical-energy-pendulum.png\" \/><\/a><span>Supposons un\u00a0<\/span><strong><span>pendule<\/span><\/strong><span>\u00a0(boule de masse m suspendue \u00e0 une cha\u00eene de longueur\u00a0<\/span><strong><span>L<\/span><\/strong><span>\u00a0que nous avons tir\u00e9e de sorte que la balle soit \u00e0 une hauteur\u00a0<\/span><strong><span>H &lt;L<\/span><\/strong><span>\u00a0au-dessus de son point le plus bas sur l&#8217;arc de son mouvement de corde tendue. Le pendule est soumis au\u00a0<\/span><strong><span>conservateur force gravitationnelle<\/span><\/strong><span>\u00a0o\u00f9 les forces de friction comme la tra\u00een\u00e9e d&#8217;air et la friction au pivot sont n\u00e9gligeables.<\/span><\/p>\n<p><span>Nous le lib\u00e9rons du repos.\u00a0<\/span><strong><span>\u00c0 quelle vitesse va-t-il au fond?<\/span><\/strong><\/p>\n<p><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/conservartion-of-mechanical-energy-pendulum2.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-15714 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/conservartion-of-mechanical-energy-pendulum2.png\" alt=\"pendule \u00e0 conservation d'\u00e9nergie m\u00e9canique2\" width=\"322\" height=\"115\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/conservartion-of-mechanical-energy-pendulum2.png\" \/><\/a><\/p>\n<p><span>Le pendule atteint la\u00a0<\/span><strong><span>plus grande \u00e9nergie cin\u00e9tique<\/span><\/strong><span>\u00a0et le\u00a0<\/span><strong><span>moins d&#8217;\u00e9nergie potentielle<\/span><\/strong><span>\u00a0lorsqu&#8217;il est en\u00a0<\/span><strong><span>position verticale<\/span><\/strong><span>\u00a0, car il aura la plus grande vitesse et sera le plus proche de la Terre \u00e0 ce point.\u00a0D&#8217;un autre c\u00f4t\u00e9, il aura sa\u00a0<\/span><strong><span>moindre \u00e9nergie cin\u00e9tique<\/span><\/strong><span>\u00a0et sa\u00a0<\/span><strong><span>plus grande \u00e9nergie potentielle<\/span><\/strong><span>\u00a0aux\u00a0<\/span><strong><span>positions extr\u00eames<\/span><\/strong><span>\u00a0de son swing, car il a une vitesse nulle et est le plus \u00e9loign\u00e9 de la Terre en ces points.<\/span><\/p>\n<p><span>Si l&#8217;amplitude est limit\u00e9e \u00e0 de petites oscillations, la p\u00e9riode\u00a0<\/span><em><span>T<\/span><\/em><span>\u00a0d&#8217;un simple pendule, le temps pris pour un cycle complet, est:<\/span><\/p>\n<p><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/period-of-pendulum-conservation-of-energy.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-15715 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/period-of-pendulum-conservation-of-energy.png\" alt=\"p\u00e9riode-de-pendule-conservation-d'\u00e9nergie\" width=\"252\" height=\"77\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/period-of-pendulum-conservation-of-energy.png\" \/><\/a><\/p>\n<p><span>o\u00f9\u00a0<\/span><strong><em><span>L<\/span><\/em><\/strong><span>\u00a0est la longueur du pendule et\u00a0<\/span><strong><em><span>g<\/span><\/em><\/strong><span>\u00a0est l&#8217;acc\u00e9l\u00e9ration locale de la gravit\u00e9.\u00a0Pour les petites balan\u00e7oires, la p\u00e9riode de balancement est approximativement la m\u00eame pour les balan\u00e7oires de tailles diff\u00e9rentes.\u00a0Autrement dit,\u00a0\u00a0<\/span><strong><span>la p\u00e9riode est ind\u00e9pendante de l&#8217;amplitude<\/span><\/strong><span>\u00a0.<\/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\">\n<div class=\"su-spacer\"><\/div>\n<h2><span>\u00c9nergie cin\u00e9tique relativiste<\/span><\/h2>\n<figure id=\"attachment_16610\" class=\"wp-caption alignright\" aria-describedby=\"caption-attachment-16610\"><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/relativistic-kinetic-energy.png\"><img loading=\"lazy\" class=\"size-medium wp-image-16610 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/relativistic-kinetic-energy-300x182.png\" alt=\"\u00e9nergie cin\u00e9tique relativiste\" width=\"300\" height=\"182\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/relativistic-kinetic-energy-300x182.png\" \/><\/a><figcaption id=\"caption-attachment-16610\" class=\"wp-caption-text\"><span>Lorsque la vitesse d&#8217;un objet s&#8217;approche de la vitesse de la lumi\u00e8re, l&#8217;\u00e9nergie cin\u00e9tique relativiste approche de l&#8217;infini.\u00a0Elle est caus\u00e9e par le facteur de Lorentz, qui se rapproche de l&#8217;infini pour v \u2192 c.<\/span><\/figcaption><\/figure>\n<p><span>La relation pr\u00e9c\u00e9dente entre le travail et l&#8217;\u00e9nergie cin\u00e9tique est bas\u00e9e sur\u00a0<\/span><strong><span>les lois du mouvement de Newton<\/span><\/strong><span>\u00a0.\u00a0Lorsque nous g\u00e9n\u00e9ralisons ces lois selon le principe de la relativit\u00e9, nous avons besoin d&#8217;une g\u00e9n\u00e9ralisation correspondante de l&#8217;\u00e9quation de\u00a0<\/span><strong><span>l&#8217;\u00e9nergie cin\u00e9tique<\/span><\/strong><span>\u00a0.\u00a0Si la vitesse d&#8217;un objet est proche de la vitesse de la lumi\u00e8re, il est n\u00e9cessaire d&#8217;utiliser\u00a0<\/span><strong><span>la m\u00e9canique relativiste<\/span><\/strong><span>\u00a0pour calculer son\u00a0<\/span><strong><span>\u00e9nergie cin\u00e9tique<\/span><\/strong><span>\u00a0.<\/span><\/p>\n<p><span>En\u00a0<\/span><strong><span>m\u00e9canique classique<\/span><\/strong><span>\u00a0, l&#8217;\u00e9nergie cin\u00e9tique et l&#8217;\u00e9lan sont exprim\u00e9s comme:<\/span><\/p>\n<p><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/classical-momentum-and-kinetic-energy.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-16618 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/classical-momentum-and-kinetic-energy.png\" alt=\"\u00e9lan classique et \u00e9nergie cin\u00e9tique\" width=\"295\" height=\"113\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/classical-momentum-and-kinetic-energy.png\" \/><\/a><\/p>\n<p><span>La d\u00e9rivation de ses\u00a0<\/span><strong><span>relations relativistes<\/span><\/strong><span>\u00a0est bas\u00e9e sur la\u00a0<strong>relation\u00a0<\/strong><\/span><strong><span>relativiste\u00a0<\/span><\/strong><strong><span>\u00e9nergie-momentum:<\/span><\/strong><\/p>\n<p><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/energy-momentum-relation.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-16620 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/energy-momentum-relation.png\" alt=\"relation \u00e9nergie-impulsion\" width=\"217\" height=\"51\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/energy-momentum-relation.png\" \/><\/a><\/p>\n<p><span>Elle peut \u00eatre d\u00e9riv\u00e9e, l&#8217;\u00a0<\/span><strong><span>\u00e9nergie cin\u00e9tique relativiste<\/span><\/strong><span>\u00a0et la quantit\u00e9 de mouvement relativiste sont:<\/span><\/p>\n<p><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/relativistic-kinetic-energy-formula.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-16619 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/relativistic-kinetic-energy-formula.png\" alt=\"\u00e9nergie cin\u00e9tique relativiste - formule\" width=\"350\" height=\"145\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/relativistic-kinetic-energy-formula.png\" \/><\/a><\/p>\n<p><span>Le premier terme (\u00a0<\/span><strong><span>\u0263mc\u00a0<\/span><sup><span>2<\/span><\/sup><\/strong><span>\u00a0) de l&#8217;\u00a0<\/span><strong><span>\u00e9nergie cin\u00e9tique relativiste<\/span><\/strong><span>\u00a0augmente avec la vitesse v de la particule.\u00a0Le deuxi\u00e8me terme (\u00a0<\/span><strong><span>mc\u00a0<\/span><sup><span>2<\/span><\/sup><\/strong><span>\u00a0) est constant;\u00a0elle est appel\u00e9e\u00a0<\/span><strong><span>\u00e9nergie de repos<\/span><\/strong><span>\u00a0\u00a0(masse au repos) de la particule et repr\u00e9sente une forme d&#8217;\u00e9nergie qu&#8217;une particule poss\u00e8de m\u00eame lorsqu&#8217;elle est \u00e0\u00a0<\/span><strong><span>vitesse nulle<\/span><\/strong><span>\u00a0.\u00a0Lorsque la vitesse d&#8217;un objet s&#8217;approche de la vitesse de la lumi\u00e8re, l&#8217;\u00a0<\/span><strong><span>\u00e9nergie cin\u00e9tique s&#8217;approche de l&#8217;infini<\/span><\/strong><span>\u00a0.\u00a0Elle est caus\u00e9e par le\u00a0<\/span><strong><span>facteur de Lorentz<\/span><\/strong><span>\u00a0, qui se rapproche de l&#8217;infini pour\u00a0<\/span><strong><span>v \u2192 c<\/span><\/strong><span>\u00a0.\u00a0Par cons\u00e9quent, la vitesse de la lumi\u00e8re ne peut \u00eatre atteinte par aucune particule massive.<\/span><\/p>\n<p><span>Le premier terme (\u0263mc\u00a0<\/span><sup><span>2<\/span><\/sup><span>\u00a0) est connu comme l&#8217;\u00a0<\/span><strong><span>\u00e9nergie totale E<\/span><\/strong><span>\u00a0de la particule, car il est \u00e9gal \u00e0 l&#8217;\u00e9nergie de repos plus l&#8217;\u00e9nergie cin\u00e9tique:<\/span><\/p>\n<p><span>E = K + mc\u00a0<\/span><sup><span>2<\/span><\/sup><\/p>\n<p><span>Pour une particule au repos, c&#8217;est-\u00e0-dire que K est nul, l&#8217;\u00e9nergie totale est donc son \u00e9nergie de repos:<\/span><\/p>\n<p><span>E = mc\u00a0<\/span><sup><span>2<\/span><\/sup><\/p>\n<p><span>C&#8217;est l&#8217;un des r\u00e9sultats frappants de\u00a0<\/span><strong><span>la th\u00e9orie de la relativit\u00e9 d&#8217;Einstein<\/span><\/strong><span>\u00a0: la\u00a0<\/span><strong><span>masse et l&#8217;\u00e9nergie sont \u00e9quivalentes et convertibles l&#8217;<\/span><\/strong><span>\u00a0une dans l&#8217;autre.\u00a0<\/span><strong><span>L&#8217;\u00e9quivalence<\/span><\/strong><span>\u00a0de la masse et de l&#8217;\u00e9nergie est d\u00e9crite par la c\u00e9l\u00e8bre formule d&#8217;Einstein\u00a0<\/span><a href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/nuclear-energy\/emc2-meaning\/\"><strong><span>E = mc\u00a0<\/span><\/strong><strong><sup><span>2<\/span><\/sup><\/strong><\/a><span>\u00a0.\u00a0Ce r\u00e9sultat a \u00e9t\u00e9 confirm\u00e9 \u00e0 maintes reprises exp\u00e9rimentalement en physique nucl\u00e9aire et \u00e9l\u00e9mentaire des particules.\u00a0Par exemple, voir\u00a0<\/span><a href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/interaction-radiation-matter\/interaction-gamma-radiation-matter\/pair-production\/\"><span>Production de paires positrons-\u00e9lectrons<\/span><\/a><span>\u00a0ou\u00a0<\/span><a href=\"https:\/\/www.nuclear-power.com\/laws-of-conservation\/law-of-conservation-of-energy\/conservation-of-energy-in-nuclear-reactions\/\"><span>Conservation de l&#8217;\u00e9nergie dans les r\u00e9actions nucl\u00e9aires<\/span><\/a><span>\u00a0.<\/span><\/p>\n<p><span>Voir aussi:\u00a0<\/span><a title=\"Messe relativiste\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/thermodynamics\/thermodynamic-properties\/what-is-mass-and-weight\/relativistic-mass-2\/\"><span>Messe relativiste<\/span><\/a><\/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\">\n<div class=\"su-spacer\"><\/div>\n<h2><span>Exemple: \u00e9nergie cin\u00e9tique du proton<\/span><\/h2>\n<p><a href=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/what-is-proton-physics-min.png\"><img loading=\"lazy\" class=\"alignright size-medium wp-image-16556 lazy-loaded\" src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/what-is-proton-physics-min-300x300.png\" alt=\"Qu'est-ce que le proton - physique\" width=\"300\" height=\"300\" data-lazy-type=\"image\" data-src=\"https:\/\/thermal-engineering.org\/wp-content\/uploads\/2019\/05\/what-is-proton-physics-min-300x300.png\" \/><\/a><span>Un proton (\u00a0<\/span><strong><span>m = 1,67 x 10\u00a0<\/span><sup><span>-27<\/span><\/sup><span>\u00a0kg<\/span><\/strong><span>\u00a0) se d\u00e9place \u00e0 une vitesse\u00a0<\/span><strong><span>v = 0,9900c = 2,968 x 10\u00a0<\/span><sup><span>8<\/span><\/sup><span>\u00a0m \/ s<\/span><\/strong><span>\u00a0.\u00a0Quelle est son\u00a0<\/span><strong><span>\u00e9nergie cin\u00e9tique<\/span><\/strong><span>\u00a0?<\/span><\/p>\n<p><span>Selon un calcul classique, qui n&#8217;est pas correct, on obtiendrait:<\/span><\/p>\n<p><span>K = 1 \/ 2mv\u00a0<\/span><sup><span>2<\/span><\/sup><span>\u00a0= \u00bd x (1,67 x 10\u00a0<\/span><sup><span>-27<\/span><\/sup><span>\u00a0kg) x (2,968 x 10\u00a0<\/span><sup><span>8<\/span><\/sup><span>\u00a0m \/ s)\u00a0<\/span><sup><span>2<\/span><\/sup><span>\u00a0=\u00a0<\/span><strong><span>7,355 x 10\u00a0<\/span><sup><span>-11<\/span><\/sup><span>\u00a0J<\/span><\/strong><\/p>\n<p><span>Avec la correction\u00a0<\/span><strong><span>relativiste, l&#8217;\u00e9nergie cin\u00e9tique relativiste<\/span><\/strong><span>\u00a0est \u00e9gale \u00e0:<\/span><\/p>\n<p><strong><span>K = (\u0263 &#8211; 1) mc\u00a0<\/span><sup><span>2<\/span><\/sup><\/strong><\/p>\n<p><span>o\u00f9 le facteur de Lorentz<\/span><\/p>\n<p><span>\u0263 = 7,089<\/span><\/p>\n<p><span>par cons\u00e9quent<\/span><\/p>\n<p><span>K = 6,089 x (1,67 x 10\u00a0<\/span><sup><span>-27<\/span><\/sup><span>\u00a0kg) x (2,9979 x 10\u00a0<\/span><sup><span>8<\/span><\/sup><span>\u00a0m \/ s)\u00a0<\/span><sup><span>2<\/span><\/sup><span>\u00a0=\u00a0<\/span><strong><span>9,139 x 10\u00a0<\/span><sup><span>-10<\/span><\/sup><span>\u00a0J = 5,701 GeV<\/span><\/strong><\/p>\n<p><span>C&#8217;est environ\u00a0<\/span><strong><span>12 fois plus d&#8217;<\/span><\/strong><span>\u00a0\u00e9nergie que dans le calcul classique.\u00a0Selon cette relation, une acc\u00e9l\u00e9ration d&#8217;un faisceau de protons \u00e0 5,7 GeV n\u00e9cessite des \u00e9nergies qui sont dans l&#8217;ordre diff\u00e9rent.<\/span><\/p>\n<p>&nbsp;<\/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\">\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<\/div>\n","protected":false},"excerpt":{"rendered":"<p>L&#8217;\u00e9nergie cin\u00e9tique, K, est d\u00e9finie comme l&#8217;\u00e9nergie stock\u00e9e dans un objet en raison de son mouvement. Il est appel\u00e9 \u00e9nergie cin\u00e9tique, du mot grec kinetikos &#8211; mouvement.\u00a0G\u00e9nie thermique &nbsp; Qu&#8217;est-ce que l&#8217;\u00e9nergie cin\u00e9tique L&#8217;\u00e9nergie cin\u00e9tique,\u00a0K\u00a0, est d\u00e9finie comme l&#8217;\u00e9nergie stock\u00e9e dans un objet en raison de son mouvement.\u00a0Un objet en mouvement a la capacit\u00e9 de &#8230; <a title=\"Qu&#8217;est-ce que l&#8217;\u00e9nergie cin\u00e9tique &#8211; D\u00e9finition\" class=\"read-more\" href=\"https:\/\/www.thermal-engineering.org\/fr\/quest-ce-que-lenergie-cinetique-definition\/\" aria-label=\"En savoir plus sur Qu&#8217;est-ce que l&#8217;\u00e9nergie cin\u00e9tique &#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 l&#039;\u00e9nergie cin\u00e9tique - D\u00e9finition<\/title>\n<meta name=\"description\" content=\"L&#039;\u00e9nergie cin\u00e9tique, K, est d\u00e9finie comme l&#039;\u00e9nergie stock\u00e9e dans un objet en raison de son mouvement. 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