{"id":2690,"date":"2017-02-07T03:13:33","date_gmt":"2017-02-07T03:13:33","guid":{"rendered":"http:\/\/fisicaevestibular.com.br\/novo\/?page_id=2690"},"modified":"2024-09-03T14:21:58","modified_gmt":"2024-09-03T14:21:58","slug":"resolucao-comentada-fuvest-2017","status":"publish","type":"page","link":"https:\/\/fisicaevestibular.com.br\/novo\/universidades-2017\/exercicios-da-fuvest-2017\/resolucao-comentada-fuvest-2017\/","title":{"rendered":"Resolu\u00e7\u00e3o comentada \u2013 FUVEST 2017"},"content":{"rendered":"

Resolu\u00e7\u00e3o comentada<\/b><\/span><\/span><\/span> \u2013 FUVEST-017 \u2013 1<\/b><\/span><\/span><\/span>a<\/b><\/span><\/span><\/sup><\/span> Fase<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

 <\/p>\n

01- \"\"<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"Captura<\/a><\/span><\/span><\/span><\/span>\"\"<\/p>\n

02- <\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Como, pelo <\/b><\/span><\/span>enunciado, X estava eletrizada com carga de 5,0.10<\/b><\/span><\/span>-12<\/b><\/span><\/sup><\/span> C<\/b><\/span><\/span> <\/b>ela transferiu<\/b><\/span><\/span> toda sua carga <\/b><\/span><\/span>para Y,<\/b><\/span><\/span> ficando <\/b><\/span><\/span>X neutra (carga zero).<\/b><\/span><\/span><\/span><\/span><\/p>\n

Acontece que <\/b><\/span><\/span>todo corpo ligado \u00e0 Terra fica totalmente descarregado <\/b><\/span><\/span>transferindo integralmente <\/b><\/span><\/span>toda sua carga (5,0.10<\/b><\/span><\/span>-12<\/b><\/span><\/sup><\/span> C) para a Terra.<\/b><\/span><\/span> Assim <\/b><\/span><\/span>Y tamb\u00e9m ficar\u00e1 neutro com carga zero.<\/b><\/span><\/span><\/span><\/span><\/p>\n

Portanto, no <\/b><\/span><\/span>final desse processo,<\/b><\/span><\/span> as <\/b><\/span><\/span>cargas el\u00e9tricas totais dos objetos X e Y ser\u00e3o, respectivamente, zero e zero.<\/b><\/span><\/span><\/span><\/span><\/p>\n

R- A<\/b><\/span><\/span><\/span><\/span><\/p>\n

 <\/p>\n

03- <\/b><\/span><\/span><\/span>Como <\/b><\/span><\/span>toda energia emitida pelo r\u00e1dio<\/b><\/span><\/span> foi <\/b><\/span><\/span>absorvida pela \u00e1gua<\/b><\/span><\/span> e empregada exclusivamente para <\/b><\/span><\/span>elevar sua temperatura sempre no estado l\u00edquido indo do ponto de congelamento (0 <\/b><\/span><\/span>o<\/b><\/span><\/sup><\/span>C) at\u00e9 o ponto<\/b><\/span><\/span> de <\/b><\/span><\/span>ebuli\u00e7\u00e3o (100 <\/b><\/span><\/span>o<\/b><\/span><\/sup><\/span>C),<\/b><\/span><\/span> a <\/b><\/span><\/span>energia liberada<\/b><\/span><\/span> pelo r\u00e1dio foi de <\/b><\/span><\/span>Q = m.c.(\u03b8 \u2013 \u03b8<\/b><\/span><\/span>o<\/b><\/span><\/sub><\/span>)<\/b><\/span><\/span> = 1,3.1.(100 \u2013 0) \"\" <\/b><\/span><\/span><\/span><\/span><\/p>\n

Q = 130 cal. <\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Como o <\/b><\/span><\/span>experimento durou \u2206t = 1 h = 3600 s,<\/b><\/span><\/span> a <\/b><\/span><\/span>pot\u00eancia m\u00e9dia liberada pelo r\u00e1dio<\/b><\/span><\/span> \u00e9 fornecida por<\/b><\/span><\/span><\/span><\/span><\/p>\n

P = \"\"<\/b><\/span><\/span><\/span> = \"\" <\/b><\/span><\/span><\/span>= 0,14 W<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

R- C<\/b><\/span><\/span><\/span><\/span><\/p>\n

04- \"\"<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

Aplicando em <\/b><\/span><\/span>(II) a lei de Snell-Descartes<\/b><\/span><\/span> \"\" <\/b><\/span><\/span>n<\/b><\/span><\/span>poliestireno<\/b><\/span><\/sub><\/span>.seni = n<\/b><\/span><\/span>ar <\/b><\/span><\/sub><\/span>.senr<\/b><\/span><\/span> \"\" n<\/b><\/span><\/span>poliestireno<\/b><\/span><\/sub><\/span>.sen25<\/b><\/span><\/span>o<\/b><\/span><\/sup><\/span> = 1.sen40<\/b><\/span><\/span>o\"\" <\/b><\/span><\/sup><\/span>n<\/b><\/span><\/span>poliestireno<\/b><\/span><\/sub><\/span>.0,4 = 1.0,6 \"\" <\/b><\/span><\/span>n<\/b><\/span><\/span>poliestireno<\/b><\/span><\/sub><\/span> = \"\"<\/b><\/span><\/span> \"\" <\/b><\/span><\/span>n<\/b><\/span><\/span>poliestireno<\/b><\/span><\/sub><\/span> = 1,5.<\/b><\/span><\/span><\/span><\/span><\/p>\n

R- B<\/b><\/span><\/span><\/span><\/span><\/p>\n

 <\/p>\n

05- <\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

 <\/p>\n

06- <\/b><\/span><\/span><\/span>Para <\/b><\/span><\/span>calcular<\/b><\/span><\/span> a <\/b><\/span><\/span>pot\u00eancia<\/b><\/span><\/span> m\u00e1xima de <\/b><\/span><\/span>sa\u00edda que o carregador pode fornecer<\/b><\/span><\/span> voc\u00ea deve utilizar a <\/b><\/span><\/span>tens\u00e3o de sa\u00edda U = 5 V e a corrente de sa\u00edda i = 1,3 A, <\/b><\/span><\/span>fornecidas nas <\/b><\/span><\/span>especifica\u00e7\u00f5es utilizando a express\u00e3o<\/b><\/span><\/span> <\/b>P<\/b><\/span><\/span> = i.U<\/b><\/span><\/span> = 1,3.5 <\/b><\/span><\/span>= 6,5 W.<\/b><\/span><\/span> <\/b><\/span><\/span><\/p>\n

A <\/b><\/span><\/span>carga m\u00e1xima armazenada na bateria<\/b><\/span><\/span> tamb\u00e9m \u00e9 <\/b><\/span><\/span>fornecida<\/b><\/span><\/span> pelas <\/b><\/span><\/span>especifica\u00e7\u00f5es da bateria Q = 1650<\/b><\/span><\/span> <\/b>mAh <\/b><\/span><\/span>que, transformado em <\/b><\/span><\/span>coulomb (C) <\/b><\/span><\/span>fornece Q = 1650.<\/b><\/span><\/span>10<\/b><\/span><\/span>-3<\/b><\/span><\/sup><\/span>.\"\".3600s \"\" <\/b><\/span><\/span>Q = 5940 C. <\/b><\/span><\/span><\/span><\/span><\/p>\n

R- D<\/b><\/span><\/span><\/span><\/span><\/p>\n

 <\/p>\n

07- <\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

Campo magn\u00e9tico originado por um condutor retil\u00edneo extenso percorrido por corrente <\/span><\/span><\/span>el\u00e9trica<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

Dire\u00e7\u00e3o e sentido do campo magn\u00e9tico\"\"<\/b><\/span><\/span><\/span><\/span><\/p>\n

\u00a0Um dos<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>processos pr\u00e1tico<\/b><\/span><\/span>s<\/b><\/span>\u00a0<\/b><\/span><\/span>para se determinar a<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>dire\u00e7\u00e3o e o sentido do vetor indu\u00e7\u00e3o<\/b><\/span><\/span> <\/b>magn\u00e9tica \"\"\u00a0\u00a0ou vetor campo magn\u00e9tico<\/b><\/span><\/span>\u00a0\"\"<\/b><\/span><\/span>, \u00e9 a regra da m\u00e3o direita.<\/b><\/span><\/span> Esse<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>sentido de<\/b><\/span><\/span>\u00a0\"\"<\/b><\/span><\/span>\u00a0depende do sentido da corrente que o origina.<\/b><\/span><\/span><\/span><\/span><\/p>\n

Voc\u00ea<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>coloca o polegar no sentido da corrente com a m\u00e3o espalmada (primeira figura),<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>em seguida<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

voc\u00ea<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>fecha a m\u00e3o para pegar o\u00a0fio (segunda figura)<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>e o<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>sentido da \u201cfechada\u201d de m\u00e3o \u00e9 o sentido do vetor<\/b><\/span><\/span>\u00a0\"\"<\/b><\/span><\/span>\u00a0(terceira figura).<\/b><\/span><\/span><\/span><\/span><\/p>\n

Observe na<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>terceira figura que \u00a0\"\"\u00a0\u00e9 sempre tangente \u00e0s linhas de indu\u00e7\u00e3o em cada ponto.<\/b><\/span><\/span><\/span><\/span><\/p>\n

Intensidade do campo magn\u00e9tico<\/b><\/span><\/span>\u00a0\"\"<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\u00a0No caso do <\/b><\/span><\/span>exerc\u00edcio,<\/b><\/span><\/span> no <\/b><\/span><\/span>centro do quadrado, a intensidade (m\u00f3dulo) do campo magn\u00e9tico<\/b><\/span><\/span> originado por <\/b><\/span><\/span>qualquer fio \u00e9 o mesmo,<\/b><\/span><\/span> pois na <\/b><\/span><\/span>express\u00e3o B = \u03bc.i\/2.\u03c0.r todos os elementos s\u00e3o constantes.<\/b><\/span><\/span><\/span><\/span><\/p>\n

Assim o que <\/b><\/span><\/span>muda no centro de cada quadrado<\/b><\/span><\/span> \u00e9 a <\/b><\/span><\/span>dire\u00e7\u00e3o e sentido de \"\" fornecidos pela regra da m\u00e3o direita (veja teoria acima).<\/b><\/span><\/span><\/span><\/span><\/p>\n

Analise atentamente as figuras abaixo <\/b><\/span><\/span>que fornecem o<\/b><\/span><\/span> campo magn\u00e9tico resultante (total) no centro de cada quadrado.<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

R- D<\/b><\/span><\/span><\/span><\/span><\/p>\n

 <\/p>\n

08- \"\"<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"Captura<\/a><\/p>\n

09- <\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

\"Captura<\/a><\/p>\n

10- <\/b><\/span><\/span><\/span>Observe<\/b><\/span><\/span> que, pelo <\/b><\/span><\/span>enunciado, \u00e9 pedida a velocidade do parafuso em rela\u00e7\u00e3o ao ch\u00e3o do elevador<\/b><\/span><\/span> e, <\/b><\/span><\/span>antes de se desprender<\/b><\/span><\/span> do teto <\/b><\/span><\/span>(instante t<\/b><\/span><\/span>o<\/b><\/span><\/sub><\/span>),<\/b><\/span><\/span> o <\/b><\/span><\/span>parafuso encontra-se em repouso em rela\u00e7\u00e3o ao ch\u00e3o do elevador,<\/b><\/span><\/span> pois a <\/b><\/span><\/span>dist\u00e2ncia entre eles n\u00e3o est\u00e1 variando.<\/b><\/span><\/span><\/span><\/span><\/p>\n

Assim, as <\/b><\/span><\/span>alternativas a, b e c n\u00e3o satisfazem.<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"Captura<\/p>\n

Voltar para os exerc\u00edcios<\/span><\/a><\/h3>\n","protected":false},"excerpt":{"rendered":"

Resolu\u00e7\u00e3o comentada \u2013 FUVEST-017 \u2013 1a Fase   01- 02- Como, pelo enunciado, X estava eletrizada com carga de 5,0.10-12 C ela transferiu toda sua carga para Y, ficando X neutra (carga zero). Acontece que todo corpo ligado \u00e0 Terra fica totalmente descarregado transferindo integralmente toda sua carga (5,0.10-12 C) para a Terra. Assim Y tamb\u00e9m ficar\u00e1 neutro com carga<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":2687,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"om_disable_all_campaigns":false,"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"footnotes":""},"class_list":["post-2690","page","type-page","status-publish","hentry"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/2690","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/comments?post=2690"}],"version-history":[{"count":4,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/2690\/revisions"}],"predecessor-version":[{"id":3188,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/2690\/revisions\/3188"}],"up":[{"embeddable":true,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/2687"}],"wp:attachment":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/media?parent=2690"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}