{"id":14819,"date":"2018-04-23T22:19:30","date_gmt":"2018-04-23T21:19:30","guid":{"rendered":"https:\/\/www.acasinhadamatematica.pt\/?p=14819"},"modified":"2022-01-10T00:16:18","modified_gmt":"2022-01-10T00:16:18","slug":"cuidado-com-o-tempo-de-exposicao-ao-sol","status":"publish","type":"post","link":"https:\/\/www.acasinhadamatematica.pt\/?p=14819","title":{"rendered":"Cuidado com o tempo de exposi\u00e7\u00e3o ao sol"},"content":{"rendered":"<p><ul id='GTTabs_ul_14819' class='GTTabs' style='display:none'>\n<li id='GTTabs_li_0_14819' class='GTTabs_curr'><a  id=\"14819_0\" onMouseOver=\"GTTabsShowLinks('Enunciado'); return true;\"  onMouseOut=\"GTTabsShowLinks();\"  class='GTTabsLinks'>Enunciado<\/a><\/li>\n<li id='GTTabs_li_1_14819' ><a  id=\"14819_1\" onMouseOver=\"GTTabsShowLinks('Resolu\u00e7\u00e3o'); return true;\"  onMouseOut=\"GTTabsShowLinks();\"  class='GTTabsLinks'>Resolu\u00e7\u00e3o<\/a><\/li>\n<\/ul>\n\n<div class='GTTabs_divs GTTabs_curr_div' id='GTTabs_0_14819'>\n<span class='GTTabs_titles'><b>Enunciado<\/b><\/span><\/p>\n<p><a href=\"https:\/\/www.acasinhadamatematica.pt\/wp-content\/uploads\/2018\/04\/9V2Pag122-8.png\"><img loading=\"lazy\" decoding=\"async\" data-attachment-id=\"14821\" data-permalink=\"https:\/\/www.acasinhadamatematica.pt\/?attachment_id=14821\" data-orig-file=\"https:\/\/www.acasinhadamatematica.pt\/wp-content\/uploads\/2018\/04\/9V2Pag122-8.png\" data-orig-size=\"522,449\" data-comments-opened=\"1\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;,&quot;orientation&quot;:&quot;0&quot;}\" data-image-title=\"Gr\u00e1fico\" data-image-description=\"\" data-image-caption=\"\" data-medium-file=\"https:\/\/www.acasinhadamatematica.pt\/wp-content\/uploads\/2018\/04\/9V2Pag122-8-300x258.png\" data-large-file=\"https:\/\/www.acasinhadamatematica.pt\/wp-content\/uploads\/2018\/04\/9V2Pag122-8.png\" class=\"alignright wp-image-14821\" src=\"https:\/\/www.acasinhadamatematica.pt\/wp-content\/uploads\/2018\/04\/9V2Pag122-8-300x258.png\" alt=\"\" width=\"400\" height=\"344\" srcset=\"https:\/\/www.acasinhadamatematica.pt\/wp-content\/uploads\/2018\/04\/9V2Pag122-8-300x258.png 300w, https:\/\/www.acasinhadamatematica.pt\/wp-content\/uploads\/2018\/04\/9V2Pag122-8.png 522w\" sizes=\"auto, (max-width: 400px) 100vw, 400px\" \/><\/a>Quando se vai \u00e0 praia, \u00e9 preciso ter cuidado com o tempo de exposi\u00e7\u00e3o ao sol, para que n\u00e3o se forme eritema (vermelh\u00e3o na pele), devido a queimadura solar.<br \/>\nO tempo m\u00e1ximo, <em>t<\/em>, em minutos, de exposi\u00e7\u00e3o direta da pele ao sol sem formar eritema pode ser calculado atrav\u00e9s da f\u00f3rmula\u00a0\\(t = \\frac{D}{i}\\) em que:<\/p>\n<ul>\n<li><em>i<\/em> representa o \u00edndice de radia\u00e7\u00e3o solar ultravioleta;<\/li>\n<li><em>D<\/em> \u00e9 um valor constante para cada tipo de pele.<\/li>\n<\/ul>\n<p>O gr\u00e1fico que se apresenta traduz essa rela\u00e7\u00e3o para o tipo da pele da Ana.<\/p>\n<ol>\n<li>A Ana foi \u00e0 praia numa altura em que o \u00edndice de radia\u00e7\u00e3o solar ultravioleta era 5.\u00a0Quantos minutos, no m\u00e1ximo, \u00e9 que ela poder\u00e1 ter a pele diretamente exposta ao sol, sem ficar com eritema?<\/li>\n<li>Num outro dia em que foi \u00e0 praia, a Ana chegou \u00e0s 10 horas da manh\u00e3, mas sabia que teria de ir embora \u00e0s 10 horas e 25 minutos.\u00a0Qual era o \u00edndice de radia\u00e7\u00e3o solar ultravioleta nesse dia?<\/li>\n<li><a href=\"https:\/\/www.acasinhadamatematica.pt\/wp-content\/uploads\/2018\/04\/9V2Pag122-8b.png\"><img loading=\"lazy\" decoding=\"async\" data-attachment-id=\"14823\" data-permalink=\"https:\/\/www.acasinhadamatematica.pt\/?attachment_id=14823\" data-orig-file=\"https:\/\/www.acasinhadamatematica.pt\/wp-content\/uploads\/2018\/04\/9V2Pag122-8b.png\" data-orig-size=\"768,289\" data-comments-opened=\"1\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;,&quot;orientation&quot;:&quot;0&quot;}\" data-image-title=\"Tabela\" data-image-description=\"\" data-image-caption=\"\" data-medium-file=\"https:\/\/www.acasinhadamatematica.pt\/wp-content\/uploads\/2018\/04\/9V2Pag122-8b-300x113.png\" data-large-file=\"https:\/\/www.acasinhadamatematica.pt\/wp-content\/uploads\/2018\/04\/9V2Pag122-8b.png\" class=\"alignright wp-image-14823\" src=\"https:\/\/www.acasinhadamatematica.pt\/wp-content\/uploads\/2018\/04\/9V2Pag122-8b-300x113.png\" alt=\"\" width=\"470\" height=\"177\" srcset=\"https:\/\/www.acasinhadamatematica.pt\/wp-content\/uploads\/2018\/04\/9V2Pag122-8b-300x113.png 300w, https:\/\/www.acasinhadamatematica.pt\/wp-content\/uploads\/2018\/04\/9V2Pag122-8b.png 768w, https:\/\/www.acasinhadamatematica.pt\/wp-content\/uploads\/2018\/04\/9V2Pag122-8b-1320x500.png 1320w\" sizes=\"auto, (max-width: 470px) 100vw, 470px\" \/><\/a>Na tabela, apresentam-se, para cada um dos principais tipos de pele da popula\u00e7\u00e3o europeia, algumas das caracter\u00edsticas f\u00edsicas que lhe est\u00e3o associadas e o valor da constante <em>D<\/em>.<br \/>\nQual \u00e9 a cor do cabelo da Ana?<br \/>\nExplica como obtiveste a tua resposta.<\/li>\n<\/ol>\n<p><div class='GTTabsNavigation' style='display:none'><span class='GTTabs_nav_next'><a href='#GTTabs_ul_14819' onClick='GTTabs_show(1,14819)'>Resolu\u00e7\u00e3o &gt;&gt;<\/a><\/span><\/div><\/div>\n\n<div class='GTTabs_divs' id='GTTabs_1_14819'>\n<span class='GTTabs_titles'><b>Resolu\u00e7\u00e3o<\/b><\/span><!--more--><\/p>\n<blockquote>\n<p><a href=\"https:\/\/www.acasinhadamatematica.pt\/wp-content\/uploads\/2018\/04\/9V2Pag122-8.png\"><img loading=\"lazy\" decoding=\"async\" data-attachment-id=\"14821\" data-permalink=\"https:\/\/www.acasinhadamatematica.pt\/?attachment_id=14821\" data-orig-file=\"https:\/\/www.acasinhadamatematica.pt\/wp-content\/uploads\/2018\/04\/9V2Pag122-8.png\" data-orig-size=\"522,449\" data-comments-opened=\"1\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;,&quot;orientation&quot;:&quot;0&quot;}\" data-image-title=\"Gr\u00e1fico\" data-image-description=\"\" data-image-caption=\"\" data-medium-file=\"https:\/\/www.acasinhadamatematica.pt\/wp-content\/uploads\/2018\/04\/9V2Pag122-8-300x258.png\" data-large-file=\"https:\/\/www.acasinhadamatematica.pt\/wp-content\/uploads\/2018\/04\/9V2Pag122-8.png\" class=\"alignright wp-image-14821\" src=\"https:\/\/www.acasinhadamatematica.pt\/wp-content\/uploads\/2018\/04\/9V2Pag122-8-300x258.png\" alt=\"\" width=\"400\" height=\"344\" srcset=\"https:\/\/www.acasinhadamatematica.pt\/wp-content\/uploads\/2018\/04\/9V2Pag122-8-300x258.png 300w, https:\/\/www.acasinhadamatematica.pt\/wp-content\/uploads\/2018\/04\/9V2Pag122-8.png 522w\" sizes=\"auto, (max-width: 400px) 100vw, 400px\" \/><\/a>Quando se vai \u00e0 praia, \u00e9 preciso ter cuidado com o tempo de exposi\u00e7\u00e3o ao sol, para que n\u00e3o se forme eritema (vermelh\u00e3o na pele), devido a queimadura solar.<br \/>\nO tempo m\u00e1ximo, <em>t<\/em>, em minutos, de exposi\u00e7\u00e3o direta da pele ao sol sem formar eritema pode ser calculado atrav\u00e9s da f\u00f3rmula\u00a0\\(t = \\frac{D}{i}\\) em que:<\/p>\n<ul>\n<li><em>i<\/em> representa o \u00edndice de radia\u00e7\u00e3o solar ultravioleta;<\/li>\n<li><em>D<\/em> \u00e9 um valor constante para cada tipo de pele.<\/li>\n<\/ul>\n<p>O gr\u00e1fico que se apresenta traduz essa rela\u00e7\u00e3o para o tipo da pele da Ana.<\/p>\n<\/blockquote>\n<p>\u00ad<\/p>\n<ol>\n<li>De acordo com o gr\u00e1fico, como a Ana foi \u00e0 praia numa altura em que o \u00edndice de radia\u00e7\u00e3o solar ultravioleta era 5, ent\u00e3o poder\u00e1 ter, no m\u00e1ximo, 40 minutos a pele diretamente exposta ao sol, sem ficar com eritema.<br \/>\n\u00ad<\/li>\n<li>De acordo com o gr\u00e1fico, se o tempo m\u00e1ximo de exposi\u00e7\u00e3o era de 25 minutos, ent\u00e3o o \u00edndice de radia\u00e7\u00e3o solar ultravioleta nesse dia era 8.<br \/>\n\u00ad<\/li>\n<li><a href=\"https:\/\/www.acasinhadamatematica.pt\/wp-content\/uploads\/2018\/04\/9V2Pag122-8b.png\"><img loading=\"lazy\" decoding=\"async\" data-attachment-id=\"14823\" data-permalink=\"https:\/\/www.acasinhadamatematica.pt\/?attachment_id=14823\" data-orig-file=\"https:\/\/www.acasinhadamatematica.pt\/wp-content\/uploads\/2018\/04\/9V2Pag122-8b.png\" data-orig-size=\"768,289\" data-comments-opened=\"1\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;,&quot;orientation&quot;:&quot;0&quot;}\" data-image-title=\"Tabela\" data-image-description=\"\" data-image-caption=\"\" data-medium-file=\"https:\/\/www.acasinhadamatematica.pt\/wp-content\/uploads\/2018\/04\/9V2Pag122-8b-300x113.png\" data-large-file=\"https:\/\/www.acasinhadamatematica.pt\/wp-content\/uploads\/2018\/04\/9V2Pag122-8b.png\" class=\"alignright wp-image-14823\" src=\"https:\/\/www.acasinhadamatematica.pt\/wp-content\/uploads\/2018\/04\/9V2Pag122-8b-300x113.png\" alt=\"\" width=\"470\" height=\"177\" srcset=\"https:\/\/www.acasinhadamatematica.pt\/wp-content\/uploads\/2018\/04\/9V2Pag122-8b-300x113.png 300w, https:\/\/www.acasinhadamatematica.pt\/wp-content\/uploads\/2018\/04\/9V2Pag122-8b.png 768w, https:\/\/www.acasinhadamatematica.pt\/wp-content\/uploads\/2018\/04\/9V2Pag122-8b-1320x500.png 1320w\" sizes=\"auto, (max-width: 470px) 100vw, 470px\" \/><\/a>O ponto de coordenadas\u00a0\\(\\left( {5,\\;40} \\right)\\), por exemplo, \u00e9 um ponto do gr\u00e1fico da fun\u00e7\u00e3o dada acima. Determinemos, ent\u00e3o, o valor da constante D correspondente ao tipo de pele da Ana:\\[\\begin{array}{*{20}{l}}{40 = \\frac{D}{5}}&amp; \\Leftrightarrow &amp;{D = 40 \\times 5}\\\\{}&amp; \\Leftrightarrow &amp;{D = 200}\\end{array}\\]Assim, de acordo com a informa\u00e7\u00e3o da tabela, conclui-se que a cor do cabelo da Ana \u00e9 ruivo.<\/li>\n<\/ol>\n<div class='GTTabsNavigation' style='display:none'><span class='GTTabs_nav_prev'><a href='#GTTabs_ul_14819' onClick='GTTabs_show(0,14819)'>&lt;&lt; Enunciado<\/a><\/span><\/div><\/div>\n\n","protected":false},"excerpt":{"rendered":"<p>Enunciado Resolu\u00e7\u00e3o Enunciado Quando se vai \u00e0 praia, \u00e9 preciso ter cuidado com o tempo de exposi\u00e7\u00e3o ao sol, para que n\u00e3o se forme eritema (vermelh\u00e3o na pele), devido a queimadura solar. O tempo&#46;&#46;&#46;<\/p>\n","protected":false},"author":1,"featured_media":14822,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[213,97,249],"tags":[426,503,250],"series":[],"class_list":["post-14819","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-9--ano","category-aplicando","category-proporcionalidade-inversa-e-funcoes-algebricas","tag-9-o-ano","tag-funcao-de-proporcionalidade-inversa","tag-proporcionalidade-inversa-2"],"views":3236,"jetpack_featured_media_url":"https:\/\/www.acasinhadamatematica.pt\/wp-content\/uploads\/2018\/04\/9V2Pag122-8a.png","jetpack_sharing_enabled":true,"jetpack_likes_enabled":true,"_links":{"self":[{"href":"https:\/\/www.acasinhadamatematica.pt\/index.php?rest_route=\/wp\/v2\/posts\/14819","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.acasinhadamatematica.pt\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.acasinhadamatematica.pt\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.acasinhadamatematica.pt\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.acasinhadamatematica.pt\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=14819"}],"version-history":[{"count":0,"href":"https:\/\/www.acasinhadamatematica.pt\/index.php?rest_route=\/wp\/v2\/posts\/14819\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.acasinhadamatematica.pt\/index.php?rest_route=\/wp\/v2\/media\/14822"}],"wp:attachment":[{"href":"https:\/\/www.acasinhadamatematica.pt\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=14819"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.acasinhadamatematica.pt\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=14819"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.acasinhadamatematica.pt\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=14819"},{"taxonomy":"series","embeddable":true,"href":"https:\/\/www.acasinhadamatematica.pt\/index.php?rest_route=%2Fwp%2Fv2%2Fseries&post=14819"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}