{"id":16661,"date":"2024-09-20T11:43:47","date_gmt":"2024-09-20T14:43:47","guid":{"rendered":"https:\/\/xequematenem.com.br\/blog\/?p=16661"},"modified":"2024-09-20T11:43:49","modified_gmt":"2024-09-20T14:43:49","slug":"questao-102-enem-2019","status":"publish","type":"post","link":"https:\/\/xequematenem.com.br\/blog\/questao-102-enem-2019\/","title":{"rendered":"Quest\u00e3o 102 &#8211; ENEM 2019"},"content":{"rendered":"\n<p>O objetivo de recipientes isolantes t\u00e9rmicos \u00e9 minimizar as trocas de calor com o ambiente externo. Essa troca de calor \u00e9 proporcional \u00e0 condutividade t\u00e9rmica k e \u00e0 \u00e1rea interna das faces do recipiente, bem como \u00e0 diferen\u00e7a de temperatura entre o ambiente externo e o interior do recipiente, al\u00e9m de ser inversamente proporcional \u00e0 espessura das faces.&nbsp;<\/p>\n\n\n\n<p>A fim de avaliar a qualidade de dois recipientes <strong>A<\/strong> (40 cm \u00d7 40 cm \u00d7 40 cm) e <strong>B<\/strong> (60 cm \u00d7 40 cm \u00d7 40 cm), de faces de mesma espessura, uma estudante compara suas condutividades t\u00e9rmicas K<sub>A<\/sub> e K<sub>B<\/sub>. Para isso suspende, dentro de cada recipiente, blocos id\u00eanticos de gelo a 0 \u00b0C, de modo que suas superf\u00edcies estejam em contato apenas com o ar. Ap\u00f3s um intervalo de tempo, ela abre os recipientes enquanto ambos ainda cont\u00eam um pouco de gelo e verifica que a massa de gelo que se fundiu no recipiente B foi o dobro da que se fundiu no recipiente A. A raz\u00e3o K<sub>A<\/sub>\/K<sub>B<\/sub> \u00e9 mais pr\u00f3xima de&nbsp;<\/p>\n\n\n\n<p>A) 0,50.&nbsp;<\/p>\n\n\n\n<p>B) 0,67.&nbsp;<\/p>\n\n\n\n<p>C) 0,75.&nbsp;<\/p>\n\n\n\n<p>D) 1,33.&nbsp;<\/p>\n\n\n\n<p>E) 2,00.<\/p>\n\n\n\n<p class=\"has-text-align-center has-large-font-size\"><strong>Solu\u00e7\u00e3o<\/strong><\/p>\n\n\n\n<p>A troca de calor com o ambiente pode ser aferida atrav\u00e9s do fluxo do calor,\u03a6, que \u00e9 a medida da varia\u00e7\u00e3o da quantidade de calor, Q, em um intervalo de tempo t:<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" width=\"83\" height=\"41\" data-src=\"https:\/\/xequematenem.com.br\/blog\/wp-content\/uploads\/2024\/09\/image-488.png\" alt=\"\" class=\"wp-image-16662 lazyload\" title=\"\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 83px; --smush-placeholder-aspect-ratio: 83\/41;\"><\/figure>\n\n\n\n<p>Devido a mudan\u00e7a para a fase s\u00f3lida o calor que atua no problema \u00e9 o calor latente, dado por<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" width=\"112\" height=\"46\" data-src=\"https:\/\/xequematenem.com.br\/blog\/wp-content\/uploads\/2024\/09\/image-489.png\" alt=\"\" class=\"wp-image-16663 lazyload\" title=\"\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 112px; --smush-placeholder-aspect-ratio: 112\/46;\"><\/figure>\n\n\n\n<p>Onde m \u00e9 a massa e L \u00e9 o calor latente. Assim,&nbsp;<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" width=\"88\" height=\"37\" data-src=\"https:\/\/xequematenem.com.br\/blog\/wp-content\/uploads\/2024\/09\/image-490.png\" alt=\"\" class=\"wp-image-16664 lazyload\" title=\"\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 88px; --smush-placeholder-aspect-ratio: 88\/37;\"><\/figure>\n\n\n\n<p>Por outro lado, o enunciado ressalta que esse fluxo \u00e9 proporcional \u00e0 k, \u00e0 \u00e1rea total interna das faces A \u00e0 diferen\u00e7a de temperatura externa e interna T, mas inversamente proporcional \u00e0 espessura e das paredes.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" width=\"144\" height=\"143\" data-src=\"https:\/\/xequematenem.com.br\/blog\/wp-content\/uploads\/2024\/09\/image-491.png\" alt=\"\" class=\"wp-image-16665 lazyload\" title=\"\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 144px; --smush-placeholder-aspect-ratio: 144\/143;\"><\/figure>\n\n\n\n<p>Para os recipientes A e B<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" width=\"349\" height=\"256\" data-src=\"https:\/\/xequematenem.com.br\/blog\/wp-content\/uploads\/2024\/09\/image-492.png\" alt=\"\" class=\"wp-image-16666 lazyload\" title=\"\" data-srcset=\"https:\/\/xequematenem.com.br\/blog\/wp-content\/uploads\/2024\/09\/image-492.png 349w, https:\/\/xequematenem.com.br\/blog\/wp-content\/uploads\/2024\/09\/image-492-300x220.png 300w\" data-sizes=\"(max-width: 349px) 100vw, 349px\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 349px; --smush-placeholder-aspect-ratio: 349\/256;\" \/><\/figure>\n\n\n\n<p>O recipiente <strong>A<\/strong> \u00e9 uma caixa quadrada, possui 6 faces, cada uma com 0,4 m \u00d7 0,4 m de \u00e1rea.&nbsp;<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" width=\"235\" height=\"50\" data-src=\"https:\/\/xequematenem.com.br\/blog\/wp-content\/uploads\/2024\/09\/image-493.png\" alt=\"\" class=\"wp-image-16667 lazyload\" title=\"\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 235px; --smush-placeholder-aspect-ratio: 235\/50;\"><\/figure>\n\n\n\n<p>J\u00e1 o recipiente <strong>B<\/strong> \u00e9 uma caixa retangular, possui 6 faces, 4 com 0,6 m \u00d7 0,4 m de \u00e1rea e 2 com 0,4 m \u00d7 0,4 m.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" width=\"325\" height=\"29\" data-src=\"https:\/\/xequematenem.com.br\/blog\/wp-content\/uploads\/2024\/09\/image-494.png\" alt=\"\" class=\"wp-image-16668 lazyload\" title=\"\" data-srcset=\"https:\/\/xequematenem.com.br\/blog\/wp-content\/uploads\/2024\/09\/image-494.png 325w, https:\/\/xequematenem.com.br\/blog\/wp-content\/uploads\/2024\/09\/image-494-300x27.png 300w\" data-sizes=\"(max-width: 325px) 100vw, 325px\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 325px; --smush-placeholder-aspect-ratio: 325\/29;\" \/><\/figure>\n\n\n\n<p>Substituindo os valores:<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" width=\"213\" height=\"65\" data-src=\"https:\/\/xequematenem.com.br\/blog\/wp-content\/uploads\/2024\/09\/image-495.png\" alt=\"\" class=\"wp-image-16669 lazyload\" title=\"\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 213px; --smush-placeholder-aspect-ratio: 213\/65;\"><\/figure>\n\n\n\n<p><strong>Alternativa B<\/strong><\/p>\n","protected":false},"excerpt":{"rendered":"<p>O objetivo de recipientes isolantes t\u00e9rmicos \u00e9 minimizar as trocas de calor com o ambiente externo. Essa troca de calor \u00e9 proporcional \u00e0 condutividade t\u00e9rmica k e \u00e0 \u00e1rea interna das faces do recipiente, bem como \u00e0 diferen\u00e7a de temperatura entre o ambiente externo e o interior do recipiente, al\u00e9m de ser inversamente proporcional \u00e0 [&hellip;]<\/p>\n","protected":false},"author":11,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[17,19],"tags":[],"area-do-conhecimento":[116,121],"assunto":[],"class_list":["post-16661","post","type-post","status-publish","format-standard","hentry","category-questoes-do-enem","category-19","area-do-conhecimento-ciencias-da-natureza-e-suas-tecnologias","area-do-conhecimento-fisica"],"_links":{"self":[{"href":"https:\/\/xequematenem.com.br\/blog\/wp-json\/wp\/v2\/posts\/16661","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/xequematenem.com.br\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/xequematenem.com.br\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/xequematenem.com.br\/blog\/wp-json\/wp\/v2\/users\/11"}],"replies":[{"embeddable":true,"href":"https:\/\/xequematenem.com.br\/blog\/wp-json\/wp\/v2\/comments?post=16661"}],"version-history":[{"count":1,"href":"https:\/\/xequematenem.com.br\/blog\/wp-json\/wp\/v2\/posts\/16661\/revisions"}],"predecessor-version":[{"id":16670,"href":"https:\/\/xequematenem.com.br\/blog\/wp-json\/wp\/v2\/posts\/16661\/revisions\/16670"}],"wp:attachment":[{"href":"https:\/\/xequematenem.com.br\/blog\/wp-json\/wp\/v2\/media?parent=16661"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/xequematenem.com.br\/blog\/wp-json\/wp\/v2\/categories?post=16661"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/xequematenem.com.br\/blog\/wp-json\/wp\/v2\/tags?post=16661"},{"taxonomy":"area-do-conhecimento","embeddable":true,"href":"https:\/\/xequematenem.com.br\/blog\/wp-json\/wp\/v2\/area-do-conhecimento?post=16661"},{"taxonomy":"assunto","embeddable":true,"href":"https:\/\/xequematenem.com.br\/blog\/wp-json\/wp\/v2\/assunto?post=16661"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}