{"id":51616,"date":"2020-01-29T12:58:56","date_gmt":"2020-01-29T11:58:56","guid":{"rendered":"https:\/\/www.thermal-engineering.org\/o-que-e-energia-cinetica-definicao\/"},"modified":"2020-01-29T13:00:54","modified_gmt":"2020-01-29T12:00:54","slug":"o-que-e-energia-cinetica-definicao","status":"publish","type":"post","link":"https:\/\/www.thermal-engineering.org\/pt-br\/o-que-e-energia-cinetica-definicao\/","title":{"rendered":"O que \u00e9 energia cin\u00e9tica &#8211; defini\u00e7\u00e3o"},"content":{"rendered":"<div class=\"su-quote su-quote-style-default\">\n<div class=\"su-quote-inner su-clearfix\">A energia cin\u00e9tica, K, \u00e9 definida como a energia armazenada em um objeto por causa de seu movimento.\u00a0\u00c9 chamado energia cin\u00e9tica, da palavra grega kinetikos &#8211; movimento.\u00a0Engenharia T\u00e9rmica<\/div>\n<\/div>\n<div class=\"su-divider su-divider-style-dotted\"><\/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>O que \u00e9 energia cin\u00e9tica<\/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=\"conserva\u00e7\u00e3o do p\u00eandulo de energia mec\u00e2nica\" 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>A energia cin\u00e9tica,\u00a0<em>K<\/em><\/strong>\u00a0, \u00e9 definida como a energia armazenada em um objeto por causa de seu movimento.\u00a0Um objeto em movimento tem a capacidade de fazer o trabalho e, portanto, pode-se dizer que possui energia.\u00a0\u00c9 chamado de energia cin\u00e9tica, da palavra grega kinetikos, que significa &#8220;movimento&#8221;.<\/p>\n<p>A\u00a0<strong>energia cin\u00e9tica<\/strong>\u00a0depende da velocidade de um objeto e \u00e9 a capacidade de um objeto em movimento de trabalhar em outros objetos quando colide com eles.\u00a0Por outro lado, a energia cin\u00e9tica de um objeto representa a quantidade de energia necess\u00e1ria para aumentar a velocidade do objeto do repouso (v = 0) para sua velocidade final.\u00a0A energia cin\u00e9tica tamb\u00e9m depende linearmente da massa, que \u00e9 uma medida num\u00e9rica da\u00a0<strong>in\u00e9rcia<\/strong>\u00a0do objeto\u00a0e a medida da resist\u00eancia de um objeto \u00e0 acelera\u00e7\u00e3o quando uma for\u00e7a \u00e9 aplicada.<\/p>\n<p>Definimos a quantidade:<\/p>\n<p><em><strong>K = \u00bd mv\u00a0<sup>2<\/sup><\/strong><\/em><\/p>\n<p>ser a\u00a0<strong>energia cin\u00e9tica translacional<\/strong> do objeto. \u00c9 preciso acrescentar que \u00e9 chamada energia cin\u00e9tica &#8220;translacional&#8221; para distingui-la da energia cin\u00e9tica rotacional.<\/p>\n<\/div>\n<\/div>\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>Conserva\u00e7\u00e3o de Energia Mec\u00e2nica<\/span><\/h2>\n<p><span>Primeiro, o princ\u00edpio da\u00a0<\/span><strong><span>Conserva\u00e7\u00e3o de Energia Mec\u00e2nica<\/span><\/strong><span>\u00a0foi declarado:<\/span><\/p>\n<p><em><strong><span>A energia mec\u00e2nica total<\/span><\/strong><span>\u00a0(definida como a soma de seu potencial e energias cin\u00e9ticas) de uma part\u00edcula que \u00e9 acionada apenas por for\u00e7as conservadoras\u00a0<\/span><strong><span>\u00e9 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=\"exemplo de conserva\u00e7\u00e3o-de-energia-mec\u00e2nica\" 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>Veja tamb\u00e9m:\u00a0<\/span><a title=\"Conserva\u00e7\u00e3o de Energia Mec\u00e2nica\" href=\"https:\/\/www.nuclear-power.com\/laws-of-conservation\/law-of-conservation-of-energy\/conservation-of-mechanical-energy\/\"><span>Conserva\u00e7\u00e3o de energia mec\u00e2nica<\/span><\/a><\/p>\n<p><strong><span>Um sistema isolado<\/span><\/strong><span>\u00a0\u00e9 aquele em que\u00a0<\/span><strong><span>nenhuma for\u00e7a externa<\/span><\/strong><span>\u00a0causa mudan\u00e7as de energia.\u00a0Se apenas\u00a0<\/span><strong><span>for\u00e7as conservadoras<\/span><\/strong><span>\u00a0atuam em um objeto e\u00a0<\/span><strong><span>U<\/span><\/strong><span>\u00a0\u00e9 a\u00a0fun\u00e7\u00e3o\u00a0<\/span><strong><span>potencial de energia<\/span><\/strong><span>\u00a0para a for\u00e7a conservadora total, ent\u00e3o<\/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>A energia potencial,\u00a0<\/span><em><span>U<\/span><\/em><\/strong><span>\u00a0, depende da posi\u00e7\u00e3o de um objeto sujeito a uma for\u00e7a conservadora.<\/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=\"equa\u00e7\u00e3o de energia potencial\" 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>\u00c9 definida como a capacidade do objeto de fazer o trabalho e \u00e9 aumentada \u00e0 medida que o objeto \u00e9 movido na dire\u00e7\u00e3o oposta \u00e0 dire\u00e7\u00e3o da for\u00e7a.<\/span><\/p>\n<p><strong><span>A energia potencial<\/span><\/strong><span>\u00a0associada a um sistema que consiste na Terra e em uma part\u00edcula pr\u00f3xima \u00e9\u00a0\u00a0<\/span><strong><span>a energia potencial gravitacional<\/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=\"equa\u00e7\u00e3o gravitacional do potencial de energia\" 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>A energia cin\u00e9tica,\u00a0<\/span><em><span>K<\/span><\/em><\/strong><span>\u00a0, depende da velocidade de um objeto e \u00e9 a capacidade de um objeto em movimento de trabalhar em outros objetos quando colide com eles.<\/span><\/p>\n<p><em><strong><span>\u00a0K = \u00bd mv\u00a0<\/span><sup><span>2<\/span><\/sup><\/strong><\/em><\/p>\n<p><span>A defini\u00e7\u00e3o acima mencionada (\u00a0<\/span><strong><span>E\u00a0<\/span><\/strong><strong><sub><span>mech<\/span><\/sub><\/strong><strong><span>\u00a0= U + K<\/span><\/strong><span>\u00a0) assume que o sistema est\u00e1\u00a0<\/span><strong><span>livre de atritos<\/span><\/strong><span>\u00a0e outras\u00a0<\/span><a title=\"Conservador - For\u00e7as n\u00e3o conservadoras\" href=\"https:\/\/www.nuclear-power.com\/laws-of-conservation\/law-of-conservation-of-energy\/conservative-nonconservative-forces\/\"><strong><span>for\u00e7as n\u00e3o conservadoras<\/span><\/strong><\/a><span>\u00a0.\u00a0A diferen\u00e7a entre uma for\u00e7a conservadora e uma n\u00e3o conservadora \u00e9 que, quando uma for\u00e7a conservadora move um objeto de um ponto para outro, o trabalho realizado pela for\u00e7a conservadora \u00e9 independente do caminho.<\/span><\/p>\n<p><span>Em qualquer situa\u00e7\u00e3o real,\u00a0<\/span><strong><span>for\u00e7as de atrito<\/span><\/strong><span>\u00a0e outras\u00a0<strong>for\u00e7as<\/strong>\u00a0n\u00e3o conservadoras est\u00e3o presentes, mas em muitos casos seus efeitos no sistema s\u00e3o t\u00e3o pequenos que o princ\u00edpio de\u00a0<\/span><strong><span>conserva\u00e7\u00e3o de energia mec\u00e2nica<\/span><\/strong><span>\u00a0pode ser usado como uma aproxima\u00e7\u00e3o justa.\u00a0Por exemplo, a for\u00e7a de atrito \u00e9 uma for\u00e7a n\u00e3o conservadora, porque atua para reduzir a energia mec\u00e2nica em um sistema.<\/span><\/p>\n<p><span>Observe que for\u00e7as n\u00e3o conservadoras nem sempre reduzem a energia mec\u00e2nica.\u00a0Uma for\u00e7a n\u00e3o conservadora altera a energia mec\u00e2nica; existem for\u00e7as que aumentam a energia mec\u00e2nica total, como a for\u00e7a fornecida por um motor ou motor, tamb\u00e9m \u00e9 uma for\u00e7a n\u00e3o conservadora.<\/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-accordion\">\n<div class=\"su-spoiler su-spoiler-style-default su-spoiler-icon-plus su-spoiler-closed\"><\/div>\n<\/div>\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<h2><span>Bloco deslizando por uma ladeira sem atrito<\/span><\/h2>\n<p><span>O bloco de 1 kg inicia uma altura H (digamos 1 m) acima do solo, com\u00a0<\/span><strong><span>energia potencial\u00a0<\/span><\/strong><strong><span>mgH<\/span><\/strong><span>\u00a0e\u00a0<\/span><strong><span>energia cin\u00e9tica<\/span><\/strong><span>\u00a0igual a 0.\u00a0<strong>Desliza<\/strong>\u00a0para o ch\u00e3o (sem atrito) e chega sem energia potencial e energia cin\u00e9tica\u00a0<\/span><strong><span>K = \u00bd mv\u00a0<\/span><sup><span>2<\/span><\/sup><\/strong><span>\u00a0.\u00a0Calcule a velocidade do bloco no ch\u00e3o e sua energia cin\u00e9tica.<\/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>P\u00eandulo<\/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=\"conserva\u00e7\u00e3o-do-p\u00eandulo-de-energia-mec\u00e2nica\" 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>Suponha um\u00a0<\/span><strong><span>p\u00eandulo<\/span><\/strong><span>\u00a0(bola de massa m suspensa em uma corda de comprimento\u00a0<\/span><strong><span>L<\/span><\/strong><span>\u00a0que t\u00eam puxado para cima de modo a que a bola \u00e9 uma altura\u00a0<\/span><strong><span>H &lt;G<\/span><\/strong><span>\u00a0acima do seu ponto mais baixo do arco do seu movimento corda esticada. O p\u00eandulo \u00e9 submetido ao\u00a0<\/span><strong><span>conservador for\u00e7a gravitacional,<\/span><\/strong><span>\u00a0onde for\u00e7as de atrito como o arrasto a\u00e9reo e o atrito no piv\u00f4 s\u00e3o desprez\u00edveis.<\/span><\/p>\n<p><span>N\u00f3s o liberamos do descanso.\u00a0<\/span><strong><span>Qu\u00e3o r\u00e1pido est\u00e1 indo no fundo?<\/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=\"conserva\u00e7\u00e3o-de-energia-mec\u00e2nica-p\u00eandulo2\" 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>O p\u00eandulo atinge a\u00a0<\/span><strong><span>maior energia cin\u00e9tica<\/span><\/strong><span>\u00a0e\u00a0<\/span><strong><span>menos energia potencial<\/span><\/strong><span>\u00a0quando na\u00a0<\/span><strong><span>posi\u00e7\u00e3o vertical<\/span><\/strong><span>\u00a0, porque ter\u00e1 a maior velocidade e estar\u00e1 mais pr\u00f3ximo da Terra neste ponto.\u00a0Por outro lado, ter\u00e1 sua\u00a0<\/span><strong><span>energia menos cin\u00e9tica<\/span><\/strong><span>\u00a0e\u00a0<\/span><strong><span>maior energia potencial<\/span><\/strong><span>\u00a0nas\u00a0<\/span><strong><span>posi\u00e7\u00f5es extremas<\/span><\/strong><span>\u00a0de seu balan\u00e7o, porque possui velocidade zero e est\u00e1 mais distante da Terra nesses pontos.<\/span><\/p>\n<p><span>Se a amplitude \u00e9 limitada a pequenas oscila\u00e7\u00f5es, o per\u00edodo\u00a0<\/span><em><span>T<\/span><\/em><span>\u00a0de um p\u00eandulo simples, o tempo necess\u00e1rio para um ciclo completo, \u00e9:<\/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=\"per\u00edodo-de-p\u00eandulo-conserva\u00e7\u00e3o-de-energia\" 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>onde\u00a0<\/span><strong><em><span>L<\/span><\/em><\/strong><span>\u00a0\u00e9 o comprimento do p\u00eandulo\u00a0<\/span><strong><em><span>eg<\/span><\/em><\/strong><span>\u00a0\u00e9 a acelera\u00e7\u00e3o local da gravidade.\u00a0Para balan\u00e7os pequenos, o per\u00edodo de oscila\u00e7\u00e3o \u00e9 aproximadamente o mesmo para balan\u00e7os de tamanhos diferentes.\u00a0Ou seja,\u00a0\u00a0<\/span><strong><span>o per\u00edodo \u00e9 independente da 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>Energia cin\u00e9tica relativ\u00edstica<\/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=\"energia cin\u00e9tica relativ\u00edstica\" 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>\u00c0 medida que a velocidade de um objeto se aproxima da velocidade da luz, a energia cin\u00e9tica relativista se aproxima do infinito.\u00a0\u00c9 causada pelo fator de Lorentz, que se aproxima do infinito para v \u2192 c.<\/span><\/figcaption><\/figure>\n<p><span>A rela\u00e7\u00e3o anterior entre trabalho e energia cin\u00e9tica \u00e9 baseada nas\u00a0<\/span><strong><span>leis do movimento de Newton<\/span><\/strong><span>\u00a0.\u00a0Quando generalizamos essas leis de acordo com o princ\u00edpio da relatividade, precisamos de uma generaliza\u00e7\u00e3o correspondente da equa\u00e7\u00e3o para\u00a0<\/span><strong><span>a energia cin\u00e9tica<\/span><\/strong><span>\u00a0.\u00a0Se a velocidade de um objeto \u00e9 pr\u00f3xima da velocidade da luz, \u00e9 necess\u00e1rio usar a\u00a0<\/span><strong><span>mec\u00e2nica relativ\u00edstica<\/span><\/strong><span>\u00a0para calcular sua\u00a0<\/span><strong><span>energia cin\u00e9tica<\/span><\/strong><span>\u00a0.<\/span><\/p>\n<p><span>Na\u00a0<\/span><strong><span>mec\u00e2nica cl\u00e1ssica<\/span><\/strong><span>\u00a0, energia cin\u00e9tica e momento s\u00e3o expressos como:<\/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=\"momento cl\u00e1ssico e energia cin\u00e9tica\" 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>A deriva\u00e7\u00e3o de suas\u00a0<\/span><strong><span>rela\u00e7\u00f5es relativ\u00edsticas<\/span><\/strong><span>\u00a0\u00e9 baseada na\u00a0<strong>rela\u00e7\u00e3o energia-momento\u00a0<\/strong><\/span><strong><span>relativista\u00a0<\/span><\/strong><strong><span>:<\/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=\"rela\u00e7\u00e3o energia-momento\" 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>Pode-se derivar, a\u00a0<\/span><strong><span>energia cin\u00e9tica relativ\u00edstica<\/span><\/strong><span>\u00a0e o momento relativ\u00edstico s\u00e3o:<\/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=\"energia cin\u00e9tica relativ\u00edstica - f\u00f3rmula\" 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>O primeiro termo (\u00a0<\/span><strong><span>\u0263mc\u00a0<\/span><sup><span>2<\/span><\/sup><\/strong><span>\u00a0) da\u00a0<\/span><strong><span>energia cin\u00e9tica relativ\u00edstica<\/span><\/strong><span>\u00a0aumenta com a velocidade v da part\u00edcula.\u00a0O segundo termo (\u00a0<\/span><strong><span>mc\u00a0<\/span><sup><span>2<\/span><\/sup><\/strong><span>\u00a0) \u00e9 constante;\u00a0\u00e9 chamado de\u00a0<\/span><strong><span>energia restante<\/span><\/strong><span>\u00a0\u00a0(massa restante) da part\u00edcula e representa uma forma de energia que uma part\u00edcula possui mesmo quando em\u00a0<\/span><strong><span>velocidade zero<\/span><\/strong><span>\u00a0.\u00a0\u00c0 medida que a velocidade de um objeto se aproxima da velocidade da luz, a\u00a0<\/span><strong><span>energia cin\u00e9tica se aproxima do infinito<\/span><\/strong><span>\u00a0.\u00a0\u00c9 causada pelo\u00a0<\/span><strong><span>fator de Lorentz<\/span><\/strong><span>\u00a0, que se aproxima do infinito para\u00a0<\/span><strong><span>v \u2192 c<\/span><\/strong><span>\u00a0.\u00a0Portanto, a velocidade da luz n\u00e3o pode ser alcan\u00e7ada por part\u00edculas maci\u00e7as.<\/span><\/p>\n<p><span>O primeiro termo (\u0263mc\u00a0<\/span><sup><span>2<\/span><\/sup><span>\u00a0) \u00e9 conhecido como\u00a0<\/span><strong><span>energia total E<\/span><\/strong><span>\u00a0da part\u00edcula, porque \u00e9 igual \u00e0 energia restante mais a energia cin\u00e9tica:<\/span><\/p>\n<p><span>E = K + mc\u00a0<\/span><sup><span>2<\/span><\/sup><\/p>\n<p><span>Para uma part\u00edcula em repouso, ou seja, K \u00e9 zero, ent\u00e3o a energia total \u00e9 sua energia de repouso:<\/span><\/p>\n<p><span>E = mc\u00a0<\/span><sup><span>2<\/span><\/sup><\/p>\n<p><span>Este \u00e9 um dos resultados marcantes da\u00a0<\/span><strong><span>teoria da relatividade de Einstein<\/span><\/strong><span>\u00a0\u00e9 que\u00a0<\/span><strong><span>massa e energia s\u00e3o equivalentes e convers\u00edveis<\/span><\/strong><span>\u00a0um no outro.\u00a0<\/span><strong><span>A equival\u00eancia<\/span><\/strong><span>\u00a0entre massa e energia \u00e9 descrita pela famosa f\u00f3rmula de 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.\u00a0Este resultado foi confirmado experimentalmente in\u00fameras vezes na f\u00edsica de part\u00edculas nuclear e elementar.\u00a0Por exemplo, consulte\u00a0<\/span><a href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/interaction-radiation-matter\/interaction-gamma-radiation-matter\/pair-production\/\"><span>Produ\u00e7\u00e3o de pares de p\u00f3sitrons com el\u00e9trons<\/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>conserva\u00e7\u00e3o de energia em rea\u00e7\u00f5es nucleares<\/span><\/a><span>\u00a0.<\/span><\/p>\n<p><span>Veja tamb\u00e9m:\u00a0<\/span><a title=\"Massa Relativ\u00edstica\" href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/thermodynamics\/thermodynamic-properties\/what-is-mass-and-weight\/relativistic-mass-2\/\"><span>Massa relativ\u00edstica<\/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>Exemplo: energia cin\u00e9tica do pr\u00f3ton<\/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=\"O que \u00e9 pr\u00f3ton - f\u00edsica\" 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>Um pr\u00f3ton (\u00a0<\/span><strong><span>m = 1,67 x\u00a0<\/span><sup><span>10-27<\/span><\/sup><span>\u00a0kg<\/span><\/strong><span>\u00a0) viaja a uma velocidade\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.\u00a0Qual \u00e9 a sua\u00a0<\/span><strong><span>energia cin\u00e9tica<\/span><\/strong><span>\u00a0?<\/span><\/p>\n<p><span>De acordo com um c\u00e1lculo cl\u00e1ssico, que n\u00e3o est\u00e1 correto, obter\u00edamos:<\/span><\/p>\n<p><span>K = 1 \/ 2mv\u00a0<\/span><sup><span>2<\/span><\/sup><span>\u00a0= \u00bd x (1,67 x\u00a0<\/span><sup><span>10-27<\/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>Com a corre\u00e7\u00e3o\u00a0<\/span><strong><span>relativ\u00edstica, a energia cin\u00e9tica relativ\u00edstica<\/span><\/strong><span>\u00a0\u00e9 igual a:<\/span><\/p>\n<p><strong><span>K = (\u0263 &#8211; 1) mc\u00a0<\/span><sup><span>2<\/span><\/sup><\/strong><\/p>\n<p><span>onde o fator de Lorentz<\/span><\/p>\n<p><span>\u0263 = 7.089<\/span><\/p>\n<p><span>Portanto<\/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\u00a0<\/span><sup><span>10-10<\/span><\/sup><span>\u00a0J = 5,701 GeV<\/span><\/strong><\/p>\n<p><span>Isso \u00e9 cerca de\u00a0<\/span><strong><span>12 vezes mais<\/span><\/strong><span>\u00a0energia do que no c\u00e1lculo cl\u00e1ssico.\u00a0De acordo com essa rela\u00e7\u00e3o, a acelera\u00e7\u00e3o de um feixe de pr\u00f3tons para 5,7 GeV requer energias da ordem diferente.<\/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 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-accordion\">\n<div class=\"su-spoiler su-spoiler-style-default su-spoiler-icon-plus su-spoiler-closed\">\n<div class=\"su-spoiler-content su-clearfix\"><\/div>\n<\/div>\n<\/div>\n<\/div>\n<div class=\"su-spoiler-title\" tabindex=\"0\" role=\"button\">\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>Este artigo \u00e9 baseado na tradu\u00e7\u00e3o autom\u00e1tica do artigo original em ingl\u00eas. Para mais informa\u00e7\u00f5es, consulte o artigo em ingl\u00eas. Voc\u00ea pode nos ajudar. Se voc\u00ea deseja corrigir a tradu\u00e7\u00e3o, envie-a para: translations@nuclear-power.com ou preencha o formul\u00e1rio de tradu\u00e7\u00e3o on-line. Agradecemos sua ajuda, atualizaremos a tradu\u00e7\u00e3o o mais r\u00e1pido poss\u00edvel. Obrigado.<\/p>\n<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>A energia cin\u00e9tica, K, \u00e9 definida como a energia armazenada em um objeto por causa de seu movimento.\u00a0\u00c9 chamado energia cin\u00e9tica, da palavra grega kinetikos &#8211; movimento.\u00a0Engenharia T\u00e9rmica O que \u00e9 energia cin\u00e9tica A energia cin\u00e9tica,\u00a0K\u00a0, \u00e9 definida como a energia armazenada em um objeto por causa de seu movimento.\u00a0Um objeto em movimento tem a &#8230; <a title=\"O que \u00e9 energia cin\u00e9tica &#8211; defini\u00e7\u00e3o\" class=\"read-more\" href=\"https:\/\/www.thermal-engineering.org\/pt-br\/o-que-e-energia-cinetica-definicao\/\" aria-label=\"More on O que \u00e9 energia cin\u00e9tica &#8211; defini\u00e7\u00e3o\">Ler mais<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":[],"categories":[14],"tags":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v15.4 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>O que \u00e9 energia cin\u00e9tica - defini\u00e7\u00e3o<\/title>\n<meta name=\"description\" content=\"A energia cin\u00e9tica, K, \u00e9 definida como a energia armazenada em um objeto por causa de seu movimento. \u00c9 chamado energia cin\u00e9tica, da palavra grega kinetikos - movimento. 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