{"id":514,"date":"2012-01-16T23:03:13","date_gmt":"2012-01-16T23:03:13","guid":{"rendered":"http:\/\/www.institutroquetes.cat\/?p=503"},"modified":"2012-01-16T23:03:13","modified_gmt":"2012-01-16T23:03:13","slug":"determinacio-del-radi-solar-2","status":"publish","type":"post","link":"https:\/\/agora.xtec.cat\/iesroquetes\/novetats\/determinacio-del-radi-solar-2\/","title":{"rendered":"Determinaci\u00f3 del Radi Solar"},"content":{"rendered":"<p><!--:ca--><strong>Determinaci\u00f3 del Radi Solar<\/strong><\/p>\n<p>Dijous, dia 1 de desembre, amb cel clar i assolellat, per\u00f2 amb temperatures baixes que ens van fer gelar a tots, els alumnes de l\u2019assignatura d\u2019astronomia van anar a la terrassa que hi ha davant del laboratori de Ci\u00e8ncies per mesurar el radi del Sol amb l&#8217;\u00fanica ajuda d\u2019una cambra fosca constru\u00efda per ells mateixos.<\/p>\n<p><a href=\"http:\/\/www.institutroquetes.cat\/galeria1.php?id=16\">Veure galeria d&#8217;imatges<\/a><br \/>\nVol\u00edem emular els antics grecs que, sense mitjans tecnol\u00f2gics sofisticats i amb coneixements rudimentaris de matem\u00e0tiques, van ser capa\u00e7os de trobar dades fonamentals del Sistema Solar, com ara, el di\u00e0metre del Sol, la Lluna i la Terra, o les distancies fins al Sol i la Lluna.<\/p>\n<p>Amb un utillatge ben senzill (un peu de rei, un metre, una cambra fosca feta de cartolina negra) i el coneixement de la llei de Tales, vam aconseguir una molt bona aproximaci\u00f3 del valor del radi solar.<\/p>\n<p>El procediment te\u00f2ric \u00e9s ben simple. Tenint en compte que la llum del Sol es propaga en l\u00ednia recta, es pot realitzar una estimaci\u00f3 del radi solar, coneixent la dist\u00e0ncia de la Terra al Sol, mesurant el di\u00e0metre de la imatge projectada d\u2019aquest astre sobre la pantalla d\u2019una cambra fosca.<\/p>\n<p>Siguin:<\/p>\n<p>D<sub>1<\/sub> \u00e0 Di\u00e0metre del Sol<\/p>\n<p>L<sub>1<\/sub> \u00e0 Dist\u00e0ncia entre la Terra i el Sol<\/p>\n<p>D<sub>2<\/sub> \u00e0 Di\u00e0metre de la projecci\u00f3 del Sol en la pantalla<\/p>\n<p>L<sub>2<\/sub> \u00e0 Longitud de la cambra fosca en la qual es projecta la imatge.<\/p>\n<p><img decoding=\"async\" alt=\"\" src=\"http:\/\/www.institutroquetes.cat\/back_office\/ckeditor_imatges\/imatges\/cambrafosca.jpg\" \/><\/p>\n<p>Els resultats experimentals foren prou bons: el valor del radi solar ens va sortir de 736.273 Km; aix\u00f2 \u00e9s tan sols d\u2019un 7% d\u2019error amb el valor real del radi solar, que \u00e9s de 690.000 Km.<!--:--><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Determinaci\u00f3 del Radi Solar Dijous, dia 1 de desembre, amb cel clar i assolellat, per\u00f2 amb temperatures baixes que ens van fer gelar a tots, els alumnes de l\u2019assignatura d\u2019astronomia van anar a la terrassa que hi ha davant del laboratori de Ci\u00e8ncies per mesurar el radi del Sol amb l&#8217;\u00fanica ajuda d\u2019una cambra fosca [&hellip;]<\/p>\n","protected":false},"author":7,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_bbp_topic_count":0,"_bbp_reply_count":0,"_bbp_total_topic_count":0,"_bbp_total_reply_count":0,"_bbp_voice_count":0,"_bbp_anonymous_reply_count":0,"_bbp_topic_count_hidden":0,"_bbp_reply_count_hidden":0,"_bbp_forum_subforum_count":0,"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center 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