{"id":6829,"date":"2015-06-16T12:55:57","date_gmt":"2015-06-16T10:55:57","guid":{"rendered":"https:\/\/kamerpower.com\/?p=6829"},"modified":"2025-01-29T21:46:26","modified_gmt":"2025-01-29T20:46:26","slug":"epreuve-concours-ensp-chimie-et-physique-cameroun-2-concours-dentree-a-lecole-nationale-superieure-polytechnique","status":"publish","type":"post","link":"https:\/\/kamerpower.com\/fr\/epreuve-concours-ensp-chimie-et-physique-cameroun-2-concours-dentree-a-lecole-nationale-superieure-polytechnique\/","title":{"rendered":"Epreuve Concours ENSP Chimie et Physique Cameroun 2 concours d&#8217;entr\u00e9e \u00e0 l\u2019Ecole Nationale Sup\u00e9rieure Polytechnique"},"content":{"rendered":"<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_82_2 counter-hierarchy ez-toc-counter ez-toc-custom ez-toc-container-direction\">\n<p class=\"ez-toc-title\" style=\"cursor:inherit\">Contents<\/p>\n<label for=\"ez-toc-cssicon-toggle-item-69e7e2bf0c9be\" class=\"ez-toc-cssicon-toggle-label\"><span class=\"ez-toc-cssicon\"><span class=\"eztoc-hide\" style=\"display:none;\">Toggle<\/span><span class=\"ez-toc-icon-toggle-span\"><svg style=\"fill: #000000;color:#000000\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" class=\"list-377408\" width=\"20px\" height=\"20px\" viewBox=\"0 0 24 24\" fill=\"none\"><path d=\"M6 6H4v2h2V6zm14 0H8v2h12V6zM4 11h2v2H4v-2zm16 0H8v2h12v-2zM4 16h2v2H4v-2zm16 0H8v2h12v-2z\" fill=\"currentColor\"><\/path><\/svg><svg style=\"fill: #000000;color:#000000\" class=\"arrow-unsorted-368013\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"10px\" height=\"10px\" viewBox=\"0 0 24 24\" version=\"1.2\" baseProfile=\"tiny\"><path d=\"M18.2 9.3l-6.2-6.3-6.2 6.3c-.2.2-.3.4-.3.7s.1.5.3.7c.2.2.4.3.7.3h11c.3 0 .5-.1.7-.3.2-.2.3-.5.3-.7s-.1-.5-.3-.7zM5.8 14.7l6.2 6.3 6.2-6.3c.2-.2.3-.5.3-.7s-.1-.5-.3-.7c-.2-.2-.4-.3-.7-.3h-11c-.3 0-.5.1-.7.3-.2.2-.3.5-.3.7s.1.5.3.7z\"\/><\/svg><\/span><\/span><\/label><input type=\"checkbox\"  id=\"ez-toc-cssicon-toggle-item-69e7e2bf0c9be\"  aria-label=\"Toggle\" \/><nav><ul class='ez-toc-list ez-toc-list-level-1 ' ><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/kamerpower.com\/fr\/epreuve-concours-ensp-chimie-et-physique-cameroun-2-concours-dentree-a-lecole-nationale-superieure-polytechnique\/#epreuve-concours-ensp-chimie-et-physique-2\" >Epreuve Concours ENSP Chimie et Physique 2<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/kamerpower.com\/fr\/epreuve-concours-ensp-chimie-et-physique-cameroun-2-concours-dentree-a-lecole-nationale-superieure-polytechnique\/#probleme-1\" >Probl\u00e8me\u00a01<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/kamerpower.com\/fr\/epreuve-concours-ensp-chimie-et-physique-cameroun-2-concours-dentree-a-lecole-nationale-superieure-polytechnique\/#kamerpower-probleme-2\" >Kamerpower Probl\u00e8me\u00a02<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/kamerpower.com\/fr\/epreuve-concours-ensp-chimie-et-physique-cameroun-2-concours-dentree-a-lecole-nationale-superieure-polytechnique\/#epreuve-concours-ensp-chimie-et-physique-cameroun-2-concours-dentree-a-lecole-nationale-superieure-polytechnique\" >Epreuve Concours ENSP Chimie et Physique Cameroun 2 concours d&#8217;entr\u00e9e \u00e0 l\u2019Ecole Nationale Sup\u00e9rieure Polytechnique<\/a><\/li><\/ul><\/nav><\/div>\n<h3 style=\"text-align: center;\"><span class=\"ez-toc-section\" id=\"epreuve-concours-ensp-chimie-et-physique-2\"><\/span><span style=\"color: #000000;\"><strong><a style=\"color: #000000;\" href=\"https:\/\/kamerpower.com\/fr\/epreuves-concours-polytechnique-cameroun-pdf\/\" target=\"_blank\" rel=\"noopener\">Epreuve Concours ENSP Chimie et Physiqu<\/a>e 2<\/strong><\/span><span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p style=\"text-align: center;\"><span style=\"color: #000000;\">Ecole Nationale Superieure Polytechnique<br \/>\n(\u00c9preuve\u00a0de Chimie et Physique ENSP)<\/span><br \/>\n<span style=\"color: #008000; text-shadow: 2px 0 2px #000;\">KA<\/span><span style=\"color: #ff0000; text-shadow: 2px 0 2px #000;\">M<\/span><span style=\"color: #ffcc00; text-shadow: 2px 0 2px #000;\">ER<\/span><span style=\"color: #800080; text-shadow: 2px 0 2px #000;\">POWER<\/span><span style=\"color: #3366ff; text-shadow: 2px 0 2px #000;\">.COM<\/span><\/p>\n<h3 style=\"text-align: center;\"><span class=\"ez-toc-section\" id=\"probleme-1\"><\/span><span style=\"color: #3366ff;\">Probl\u00e8me\u00a01<\/span><span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\">Trois charges \u00e9lectriques suppos\u00e9es ponctuelles, de m\u00eame valeur q&gt;0, sont plac\u00e9es aux trois sommets A, B et C d\u2019un carr\u00e9 de cot\u00e9 a. Elles sont maintenues fixes par un dispositif quelconque. kamerpower.com<\/span><\/p>\n<ol>\n<li><span style=\"color: #000000;\">\u00a0D\u00e9terminez le champ \u00e9lectrique <span style=\"color: #ff0000;\">E<\/span>\u00a0 au quatri\u00e8me sommet <span style=\"color: #ff0000;\">D<\/span> du carr\u00e9.<\/span><\/li>\n<li style=\"text-align: justify;\"><span style=\"color: #000000;\">\u00a0On place en <span style=\"color: #ff0000;\">D<\/span> une charge inconnue <span style=\"color: #ff0000;\">Q<\/span>. Dans quelle direction se d\u00e9placera-t-elle\u00a0?<\/span><\/li>\n<li style=\"text-align: justify;\"><span style=\"color: #000000;\">\u00a0Quelle devrait \u00eatre la valeur d\u2019une charge q\u2019, plac\u00e9e en B \u00e0 la place de la charge q, pour que <span style=\"color: #ff0000;\">Q<\/span> reste immobile quelle que soit sa valeur\u00a0? (<span style=\"color: #ff0000;\">BD<\/span> est une diagonale du carr\u00e9. On n\u00e9gligera toute interaction entre les masses.)<\/span><\/li>\n<\/ol>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\">(Application num\u00e9rique\u00a0: q = 5&#215;10<sup>-8<\/sup>C\u00a0\u00a0 )<\/span><\/p>\n<hr \/>\n<h3 style=\"text-align: center;\"><span class=\"ez-toc-section\" id=\"kamerpower-probleme-2\"><\/span><span style=\"color: #3366ff;\">Kamerpower Probl\u00e8me\u00a02<\/span><span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\">Dans tout le probl\u00e8me on n\u00e9gligera la r\u00e9sistance de l\u2019air. Les quatre questions sont ind\u00e9pendantes.<\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\"><span style=\"color: #3366ff;\">1)<\/span> Quel doit \u00eatre au d\u00e9part le module de la pouss\u00e9e <span style=\"color: #ff0000;\">p<\/span> (force verticale exerc\u00e9e par le moteur) pour qu\u2019une fus\u00e9e de masse totale <span style=\"color: #ff0000;\">M<\/span> s\u2019\u00e9l\u00e8ve verticalement avec une acc\u00e9l\u00e9ration de module\u00a0\u03b3?\u00a0<\/span><span style=\"color: #ff0000;\">\u00a0M=100 tonnes; \u03b3=8 m s<sup>-2<\/sup>; g = 10 m s<sup>-2<\/sup><\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\"><span style=\"color: #3366ff;\">2)<\/span> Cette fus\u00e9e place, \u00e0 l\u2019altitude <span style=\"color: #ff0000;\">h = 600 km<\/span>, un satellite artificiel de masse <span style=\"color: #ff0000;\">m = 2000 kg<\/span> sur une orbite circulaire ayant pour centre le centre de la terre.<\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\">Supposant que le satellite d\u00e9crit cette orbite \u00e0 une vitesse lin\u00e9aire de module <span style=\"color: #ff0000;\">v<\/span> constant, calculer (on notera <span style=\"color: #ff0000;\">Rt<\/span> le rayon terrestre)\u00a0:<\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\">L\u2019acc\u00e9l\u00e9ration de la pesanteur \u00e0 l\u2019altitude h\u00a0;\u00a0La dur\u00e9e T d\u2019une r\u00e9volution.<\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #ff0000;\">Rt = 6400 km\u00a0; v = 7700 m s<sup>-1<\/sup><\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\"><span style=\"color: #3366ff;\">3)<\/span> L\u2019orbite est en r\u00e9alit\u00e9 elliptique et par l\u00e0 m\u00eame les lois du mouvement uniforme ne s\u2019appliquent plus. A l\u2019apog\u00e9e (point le plus \u00e9loign\u00e9 de la terre) l\u2019altitude est <span style=\"color: #ff0000;\">h<sub>1<\/sub><\/span><strong><sub>\u00a0,<\/sub>\u00a0<\/strong>au p\u00e9rig\u00e9e (point le plus rapproch\u00e9 de la terre), c\u2019est <span style=\"color: #ff0000;\">h<sub>2<\/sub><\/span>.<\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\">Quelle est la vitesse du satellite \u00e0 l\u2019apog\u00e9e, si elle vaut <span style=\"color: #ff0000;\">v = 770 m s<sup>-1<\/sup><\/span> au p\u00e9rig\u00e9e? (On supposera que l\u2019acc\u00e9l\u00e9ration <span style=\"color: #ff0000;\">g<sub>m<\/sub><\/span> reste constante tout au long de la trajectoire).\u00a0<\/span><span style=\"color: #ff0000;\">\u00a0h<sub>1<\/sub> = 900 km\u00a0; h<sub>2<\/sub> = 600 km\u00a0; g<sub>m<\/sub> = 8 m s<sup>-2<\/sup><\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\"><span style=\"color: #3366ff;\">4)<\/span> Une pile \u00e0 combustible embarqu\u00e9e transforme int\u00e9gralement de l\u2019\u00e9nergie chimique en \u00e9nergie \u00e9lectrique disponible pour la le satellite. Elle r\u00e9alise la synth\u00e8se de l\u2019eau. La production d\u2019une mole d\u2019eau fournit une \u00e9nergie <span style=\"color: #ff0000;\">W = 286 kJ<\/span>.<\/span><\/p>\n<p style=\"text-align: justify;\"><span style=\"color: #000000;\">Calculez les masses d\u2019oxyg\u00e8ne et d\u2019hydrog\u00e8ne n\u00e9cessaires pour un vol orbital de <span style=\"color: #ff0000;\">N jours<\/span>, sachant que l\u2019appareil \u00e0 bord utilise une puissance moyenne <span style=\"color: #ff0000;\">P<\/span><strong>.\u00a0<\/strong><\/span><span style=\"color: #3366ff;\">N.B. ;\u00a0H = 1\u00a0; O = 16 \u00a0<\/span><span style=\"color: #ff0000;\">\u00a0N = 6 jours; P = 1 kW<\/span><\/p>\n<h2 style=\"text-align: center;\"><span class=\"ez-toc-section\" id=\"epreuve-concours-ensp-chimie-et-physique-cameroun-2-concours-dentree-a-lecole-nationale-superieure-polytechnique\"><\/span><span style=\"color: #3366ff;\">Epreuve Concours ENSP Chimie et Physique Cameroun 2 concours d&#8217;entr\u00e9e \u00e0 l\u2019Ecole Nationale Sup\u00e9rieure Polytechnique<\/span><span class=\"ez-toc-section-end\"><\/span><\/h2>\n","protected":false},"excerpt":{"rendered":"<p>&#46;&#46;&#46;<\/p>\n","protected":false},"author":1,"featured_media":5914,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_themeisle_gutenberg_block_has_review":false,"footnotes":""},"categories":[1701],"tags":[1724,1712,1727,1726],"class_list":["post-6829","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-epreuves","tag-chimie","tag-epreuve-de-concours-dentree-aux-grandes-ecoles-cameroun","tag-epreuve-ensp-concours-cameroun","tag-physique"],"_links":{"self":[{"href":"https:\/\/kamerpower.com\/fr\/wp-json\/wp\/v2\/posts\/6829","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/kamerpower.com\/fr\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/kamerpower.com\/fr\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/kamerpower.com\/fr\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/kamerpower.com\/fr\/wp-json\/wp\/v2\/comments?post=6829"}],"version-history":[{"count":1,"href":"https:\/\/kamerpower.com\/fr\/wp-json\/wp\/v2\/posts\/6829\/revisions"}],"predecessor-version":[{"id":67828,"href":"https:\/\/kamerpower.com\/fr\/wp-json\/wp\/v2\/posts\/6829\/revisions\/67828"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/kamerpower.com\/fr\/wp-json\/wp\/v2\/media\/5914"}],"wp:attachment":[{"href":"https:\/\/kamerpower.com\/fr\/wp-json\/wp\/v2\/media?parent=6829"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/kamerpower.com\/fr\/wp-json\/wp\/v2\/categories?post=6829"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/kamerpower.com\/fr\/wp-json\/wp\/v2\/tags?post=6829"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}