{"id":17202,"date":"2024-09-21T20:39:09","date_gmt":"2024-09-21T23:39:09","guid":{"rendered":"https:\/\/xequematenem.com.br\/blog\/?p=17202"},"modified":"2024-09-21T20:39:11","modified_gmt":"2024-09-21T23:39:11","slug":"questao-67-enem-ppl-2015","status":"publish","type":"post","link":"https:\/\/xequematenem.com.br\/blog\/questao-67-enem-ppl-2015\/","title":{"rendered":"Quest\u00e3o 067 &#8211; ENEM PPL 2015"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\">Num sistema de freio convencional, as rodas do carro travam e os pneus derrapam no solo, caso a for\u00e7a exercida sobre o pedal seja muito intensa. O sistema ABS evita o travamento das rodas, mantendo a for\u00e7a de atrito no seu valor est\u00e1tico m\u00e1ximo, sem derrapagem. O coeficiente de atrito est\u00e1tico da borracha em contato com o concreto vale \u00b5e = 1,0 e o coeficiente de atrito cin\u00e9tico para o mesmo par de materiais \u00e9 \u00b5c = 0,75. Dois carros, com velocidades iniciais iguais a 108 km\/h, iniciam a frenagem numa estrada perfeitamente horizontal de concreto no mesmo ponto. O carro 1 tem sistema ABS e utiliza a for\u00e7a de atrito est\u00e1tica m\u00e1xima para a frenagem; j\u00e1 o carro 2 trava as rodas, de maneira que a for\u00e7a de atrito efetiva \u00e9 a cin\u00e9tica. Considere g = 10 m\/s<sup>2<\/sup> . As dist\u00e2ncias, medidas a partir do ponto em que iniciam a frenagem, que os carros 1 (d<sub>1<\/sub> ) e 2 (d<sub>2<\/sub> ) percorrem at\u00e9 parar s\u00e3o, respectivamente,&nbsp;<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">A d<sub>1<\/sub> = 45 m e d<sub>2<\/sub> = 60 m.&nbsp;<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">B d<sub>1<\/sub> = 60 m e d<sub>2<\/sub> = 45 m.&nbsp;<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">C d<sub>1<\/sub> = 90 m e d<sub>2<\/sub> = 120 m.&nbsp;<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">D d<sub>1<\/sub> = 5,8\u00d710\u00b2 m e d<sub>2<\/sub> = 7,8\u00d710\u00b2 m.&nbsp;<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">E d<sub>1<\/sub> = 7,8\u00d710\u00b2 m e d<sub>2<\/sub> = 5,8\u00d710\u00b2 m.<\/p>\n\n\n\n<p class=\"has-text-align-center has-large-font-size wp-block-paragraph\"><strong>Solu\u00e7\u00e3o<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Para resolver essa quest\u00e3o precisamos achar a acelera\u00e7\u00e3o de ambos.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">A for\u00e7a resultante \u00e9 a pr\u00f3pria for\u00e7a de atrito, logo<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" width=\"139\" height=\"80\" data-src=\"https:\/\/xequematenem.com.br\/blog\/wp-content\/uploads\/2024\/09\/image-777.png\" alt=\"\" class=\"wp-image-17203 lazyload\" title=\"\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 139px; --smush-placeholder-aspect-ratio: 139\/80;\"><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">No caso, N \u00e9 igual a for\u00e7a peso, j\u00e1 que n\u00e3o h\u00e1 inclina\u00e7\u00e3o no plano.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" width=\"142\" height=\"86\" data-src=\"https:\/\/xequematenem.com.br\/blog\/wp-content\/uploads\/2024\/09\/image-778.png\" alt=\"\" class=\"wp-image-17204 lazyload\" title=\"\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 142px; --smush-placeholder-aspect-ratio: 142\/86;\"><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">Calculemos a acelera\u00e7\u00e3o dos dos dois por a<sub>c<\/sub> (acelera\u00e7\u00e3o do carro com o atrito cin\u00e9tico) e a<sub>e<\/sub> (acelera\u00e7\u00e3o do carro com atrito est\u00e1tico):<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" width=\"130\" height=\"96\" data-src=\"https:\/\/xequematenem.com.br\/blog\/wp-content\/uploads\/2024\/09\/image-779.png\" alt=\"\" class=\"wp-image-17205 lazyload\" title=\"\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 130px; --smush-placeholder-aspect-ratio: 130\/96;\"><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">E a acelera\u00e7\u00e3o com atrito est\u00e1tico:<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" width=\"190\" height=\"38\" data-src=\"https:\/\/xequematenem.com.br\/blog\/wp-content\/uploads\/2024\/09\/image-780.png\" alt=\"\" class=\"wp-image-17206 lazyload\" title=\"\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 190px; --smush-placeholder-aspect-ratio: 190\/38;\"><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">Agora aplicando a equa\u00e7\u00e3o de Torricelli:<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" width=\"145\" height=\"53\" data-src=\"https:\/\/xequematenem.com.br\/blog\/wp-content\/uploads\/2024\/09\/image-781.png\" alt=\"\" class=\"wp-image-17207 lazyload\" title=\"\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 145px; --smush-placeholder-aspect-ratio: 145\/53;\"><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">Ambas acelera\u00e7\u00f5es s\u00e3o negativas, pelo fato da for\u00e7a de atrito estar em oposi\u00e7\u00e3o ao movimento, ou seja, faz o carro frear.&nbsp;<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" width=\"462\" height=\"183\" data-src=\"https:\/\/xequematenem.com.br\/blog\/wp-content\/uploads\/2024\/09\/image-782.png\" alt=\"\" class=\"wp-image-17208 lazyload\" title=\"\" data-srcset=\"https:\/\/xequematenem.com.br\/blog\/wp-content\/uploads\/2024\/09\/image-782.png 462w, https:\/\/xequematenem.com.br\/blog\/wp-content\/uploads\/2024\/09\/image-782-300x119.png 300w\" data-sizes=\"(max-width: 462px) 100vw, 462px\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 462px; --smush-placeholder-aspect-ratio: 462\/183;\" \/><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">Para&nbsp; \u0394S<sub>e<\/sub><\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" width=\"209\" height=\"136\" data-src=\"https:\/\/xequematenem.com.br\/blog\/wp-content\/uploads\/2024\/09\/image-783.png\" alt=\"\" class=\"wp-image-17209 lazyload\" title=\"\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 209px; --smush-placeholder-aspect-ratio: 209\/136;\"><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Alternativa A<\/strong><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Num sistema de freio convencional, as rodas do carro travam e os pneus derrapam no solo, caso a for\u00e7a exercida sobre o pedal seja muito intensa. O sistema ABS evita o travamento das rodas, mantendo a for\u00e7a de atrito no seu valor est\u00e1tico m\u00e1ximo, sem derrapagem. O coeficiente de atrito est\u00e1tico da borracha em contato [&hellip;]<\/p>\n","protected":false},"author":11,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[87,94],"tags":[],"area-do-conhecimento":[116,121],"assunto":[],"class_list":["post-17202","post","type-post","status-publish","format-standard","hentry","category-questoes-ppl","category-2015-questoes-ppl","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\/17202","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=17202"}],"version-history":[{"count":1,"href":"https:\/\/xequematenem.com.br\/blog\/wp-json\/wp\/v2\/posts\/17202\/revisions"}],"predecessor-version":[{"id":17210,"href":"https:\/\/xequematenem.com.br\/blog\/wp-json\/wp\/v2\/posts\/17202\/revisions\/17210"}],"wp:attachment":[{"href":"https:\/\/xequematenem.com.br\/blog\/wp-json\/wp\/v2\/media?parent=17202"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/xequematenem.com.br\/blog\/wp-json\/wp\/v2\/categories?post=17202"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/xequematenem.com.br\/blog\/wp-json\/wp\/v2\/tags?post=17202"},{"taxonomy":"area-do-conhecimento","embeddable":true,"href":"https:\/\/xequematenem.com.br\/blog\/wp-json\/wp\/v2\/area-do-conhecimento?post=17202"},{"taxonomy":"assunto","embeddable":true,"href":"https:\/\/xequematenem.com.br\/blog\/wp-json\/wp\/v2\/assunto?post=17202"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}