{"id":2825,"date":"2017-04-12T04:29:19","date_gmt":"2017-04-12T04:29:19","guid":{"rendered":"http:\/\/fisicaevestibular.com.br\/novo\/?page_id=2825"},"modified":"2024-09-03T16:55:40","modified_gmt":"2024-09-03T16:55:40","slug":"resolucao-comentada-das-questoes-de-fisica-do-vestibular-da-ufmg-mg-2017","status":"publish","type":"page","link":"https:\/\/fisicaevestibular.com.br\/novo\/universidades-2017\/uemg-2017\/resolucao-comentada-das-questoes-de-fisica-do-vestibular-da-ufmg-mg-2017\/","title":{"rendered":"Resolu\u00e7\u00e3o comentada das quest\u00f5es de F\u00cdSICA do vestibular da UFMG \u2013 MG \u2013 2017"},"content":{"rendered":"

Resolu\u00e7\u00e3o comentada das quest\u00f5es de F\u00cdSICA do vestibular da <\/span><\/span><\/span><\/p>\n

UFMG \u2013 MG \u2013 2017<\/span><\/span><\/span><\/p>\n

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

\"\"<\/p>\n

P \u2013 N = \"\"<\/b><\/span><\/span><\/span> \"\" como a <\/b><\/span><\/span><\/span>for\u00e7a exercida pela pista sobre o carro tem intensidade N tal que \"\" <\/b><\/span><\/span><\/span>– N = \"\" \u2013 P \"\" <\/b><\/span><\/span><\/span>N = Mg – \"\".<\/b><\/span><\/span><\/span><\/p>\n

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

02- <\/span><\/span><\/span>Observe na <\/b><\/span><\/span><\/span>figura a <\/b><\/span><\/span><\/span>que a for\u00e7a \"\" \u00e9 <\/b><\/span><\/span><\/span>decomposta<\/b><\/span><\/span><\/span> em <\/b><\/span><\/span><\/span>duas parcelas \"\" e\"\" <\/b><\/span><\/span><\/span>e que a <\/b><\/span><\/span><\/span>parcela respons\u00e1vel pela realiza\u00e7\u00e3o do trabalho no deslocamento \u00e9 F<\/b><\/span><\/span><\/span>x<\/b><\/span><\/span><\/sub><\/span> tal que F<\/b><\/span><\/span><\/span>x<\/b><\/span><\/span><\/sub><\/span> < F.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Em <\/b><\/span><\/span><\/span>b a for\u00e7a que age no deslocamento \u00e9 \"\".<\/b><\/span><\/span><\/span><\/p>\n

Como o <\/b><\/span><\/span><\/span>trabalho <\/b><\/span><\/span><\/span>em a vale <\/b><\/span><\/span><\/span>W<\/b><\/span><\/span><\/span>a<\/b><\/span><\/span><\/sub><\/span> =F<\/b><\/span><\/span><\/span>x<\/b><\/span><\/span><\/sub><\/span>.d <\/b><\/span><\/span><\/span>e em <\/b><\/span><\/span><\/span>b<\/b><\/span><\/span><\/span> vale, <\/b><\/span><\/span><\/span>W<\/b><\/span><\/span><\/span>b<\/b><\/span><\/span><\/sub><\/span> = F.d \"\" W<\/b><\/span><\/span><\/span>a<\/b><\/span><\/span><\/sub><\/span> < W<\/b><\/span><\/span><\/span>b<\/b><\/span><\/span><\/sub><\/span>.<\/b><\/span><\/span><\/span><\/p>\n

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

03- \"\"<\/span><\/span><\/span><\/p>\n

\u03b7 = 1 – \"\"<\/b><\/span><\/span><\/span> = 1 –<\/b><\/span><\/span><\/span> \"\"<\/b><\/span><\/span><\/span> = 0,5 \"\" <\/b><\/span><\/span><\/span>\u03b7 = 50 %.<\/b><\/span><\/span><\/span><\/p>\n

T<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span> = 27 + 273 = 300 K \"\" \u03b7 = 1 – \"\"<\/b><\/span><\/span><\/span> \"\" 0,5 = 1 – \"\" \"\" – 0,5 = – \"\" \"\" <\/b><\/span><\/span><\/span>T = 600 K.<\/b><\/span><\/span><\/span><\/p>\n

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

04- <\/span><\/span><\/span>Para que <\/b><\/span><\/span><\/span>ocorra indu\u00e7\u00e3o eletromagn\u00e9tica <\/b><\/span><\/span><\/span>\u00e9 preciso que ocorra <\/b><\/span><\/span><\/span>varia\u00e7\u00e3o do fluxo magn\u00e9tic<\/b><\/span><\/span><\/span>o o que s\u00f3 ocorre quando ocorre <\/b><\/span><\/span><\/span>movimento do d\u00ednamo, produzindo corrente el\u00e9trica alternada. <\/b><\/span><\/span><\/span>Isso <\/b><\/span><\/span><\/span>n\u00e3o acontece<\/b><\/span><\/span><\/span> com as <\/b><\/span><\/span><\/span>pilhas e pain\u00e9is fotovoltaicos <\/b><\/span><\/span><\/span>que produzem <\/b><\/span><\/span><\/span>corrente cont\u00ednua.<\/b><\/span><\/span><\/span><\/p>\n

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

05- <\/span><\/span><\/span>Uma das imagens i <\/b><\/span><\/span><\/span>do objeto que <\/b><\/span><\/span><\/span>est\u00e1 antes do ponto antiprincipal A<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sub><\/span> (200 cm) <\/b><\/span><\/span><\/span>\u00e9 formada diretamente pela <\/b><\/span><\/span><\/span>lente biconvexa<\/b><\/span><\/span><\/span> (convergente) que tem as <\/b><\/span><\/span><\/span>seguintes caracter\u00edsticas<\/b><\/span><\/span><\/span>, geometricamente localizadas na <\/b><\/span><\/span><\/span>figura abaixo:<\/b><\/span><\/span><\/span><\/p>\n

Objeto O antes de A<\/b><\/span><\/span>o<\/b><\/span><\/sub><\/span><\/span><\/span><\/p>\n

Caracter\u00edsticas da imagem<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>i:<\/b><\/span><\/span><\/span><\/span><\/p>\n

Natureza<\/b><\/span><\/span>\u00a0\"\"<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>Real <\/b><\/span><\/span>(<\/b><\/span><\/span>obtida no<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>cruzamento do pr\u00f3prio raio luminoso<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>(linha cheia)<\/b><\/span><\/span>).<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Localiza\u00e7\u00e3o<\/b><\/span><\/span>\u00a0\"\"<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>entre<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>F<\/b><\/span><\/span>i<\/b><\/span><\/sub><\/span>\u00a0e A<\/b><\/span><\/span>i<\/b><\/span><\/sub><\/span>.<\/b><\/span><\/span>\u00a0\u00a0<\/b><\/span><\/span><\/span><\/span><\/p>\n

Tamanho e orienta\u00e7\u00e3o<\/b><\/span><\/span>\u00a0\"\"<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>menor que o objeto<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>e<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>invertida<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>em rela\u00e7\u00e3o ao mesmo<\/b><\/span><\/span>.<\/b><\/span><\/span><\/span><\/span><\/p>\n

A <\/b><\/span><\/span><\/span>outra imagem i\u2019 <\/b><\/span><\/span><\/span>captada pelo <\/b><\/span><\/span><\/span>espelho plano <\/b><\/span><\/span><\/span>(<\/b><\/span><\/span><\/span>real, invertida e maior que o objeto, pois o objeto<\/b><\/span><\/span><\/span> est\u00e1 <\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

a 80cm do espelho, entre o foco F = 60cm e o centro de curvatura C = 120 cm) <\/b><\/span><\/span><\/span>funciona como objeto para <\/b><\/span><\/span><\/span>a <\/b><\/span><\/span><\/span>lente biconvexa <\/b><\/span><\/span><\/span>(convergente) e <\/b><\/span><\/span><\/span>sua <\/b><\/span><\/span><\/span>imagem i\u2019\u2019<\/b><\/span><\/span><\/span>,<\/b><\/span><\/span><\/span> vista pelo observador ser\u00e1 <\/b><\/span><\/span><\/span>direita em rela\u00e7\u00e3o ao objeto, real e maior que o mesmo, <\/b><\/span><\/span><\/span>conforme constru\u00e7\u00e3o geom\u00e9trica na figura acima. <\/b><\/span><\/span><\/span><\/p>\n

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

06- <\/span><\/span><\/span>Se a <\/b><\/span><\/span><\/span>pot\u00eancia da l\u00e2mpada \u00e9 de 24 W<\/b><\/span><\/span><\/span> e o <\/b><\/span><\/span><\/span>dimer foi regulado para que ela dissipe 81 %<\/b><\/span><\/span><\/span> desse valor, ent\u00e3o a <\/b><\/span><\/span><\/span>pot\u00eancia dissipada pela l\u00e2mpada <\/b><\/span><\/span><\/span>ser\u00e1 P<\/b><\/span><\/span><\/span>d<\/b><\/span><\/span><\/sub><\/span> = 81 % de 24 W = 0,81×24 \"\" <\/b><\/span><\/span><\/span>P<\/b><\/span><\/span><\/span>d<\/b><\/span><\/span><\/sub><\/span> = 19,44 W.<\/b><\/span><\/span><\/span><\/p>\n

A <\/b><\/span><\/span><\/span>resist\u00eancia da l\u00e2mpada <\/b><\/span><\/span><\/span>deve ser determinada por seus <\/b><\/span><\/span><\/span>valores nominais \"\"<\/b><\/span><\/span><\/span> <\/b>P<\/b><\/span><\/span><\/span> = \"\"<\/b><\/span><\/span><\/sub><\/span> \"\"<\/b><\/span><\/span><\/sub><\/span> 24 =<\/b><\/span><\/span><\/span> \"\"<\/b><\/span><\/span><\/sub><\/span> <\/b><\/p>\n

\"\" R =\"\"<\/b><\/span><\/span><\/span> \"\" <\/span><\/span><\/span>R = 6 \u2126<\/b><\/span><\/span><\/span><\/p>\n

Sendo a <\/b><\/span><\/span><\/span>pot\u00eancia dissipada na l\u00e2mpada P<\/b><\/span><\/span><\/span>d<\/b><\/span><\/span><\/sub><\/span> = 19,44 W<\/b><\/span><\/span><\/span> e sua <\/b><\/span><\/span><\/span>resist\u00eancia R<\/b><\/span><\/span><\/span>L<\/b><\/span><\/span><\/sub><\/span> = 6 \u2126, <\/b><\/span><\/span><\/span>a <\/b><\/span><\/span><\/span>tens\u00e3o U\u00ad<\/b><\/span><\/span><\/span>L<\/b><\/span><\/span><\/sub><\/span> <\/b>na l\u00e2mpada ser\u00e1 \"\"<\/b><\/span><\/span><\/span> P<\/b><\/span><\/span><\/span>d<\/b><\/span><\/span><\/sub><\/span> = U<\/b><\/span><\/span><\/span>L<\/b><\/span><\/span><\/sub><\/span> \/R<\/b><\/span><\/span><\/span>L<\/b><\/span><\/span><\/sub><\/span> \"\" <\/b><\/span><\/span><\/span>19,44 = U<\/b><\/span><\/span><\/span>L<\/b><\/span><\/span><\/sub><\/span> \/6 \"\" U<\/b><\/span><\/span><\/span>L<\/b><\/span><\/span><\/sub><\/span> = \"\" \"\" <\/b><\/span><\/span><\/span>U<\/b><\/span><\/span><\/span>L<\/b><\/span><\/span><\/sub><\/span> = 10,8 V.<\/b><\/span><\/span><\/span><\/p>\n

Corrente i <\/b><\/span><\/span><\/span>na l\u00e2mpada \"\" <\/b><\/span><\/span><\/span>R<\/b><\/span><\/span><\/span>L<\/b><\/span><\/span><\/sub><\/span> =U <\/b><\/span><\/span><\/span>L<\/b><\/span><\/span><\/sub><\/span>\/i<\/b><\/span><\/span><\/span> \"\" 6 = \"\" \"\"<\/b><\/span><\/span><\/span> i = 1,8 A.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Como o dimer e a l\u00e2mpada est\u00e3 associados em s\u00e9rie <\/b><\/span><\/span><\/span>a <\/b><\/span><\/span><\/span>corrente em cada um deles \u00e9 a mesma <\/b><\/span><\/span><\/span>(i = 1,8 A) e a <\/b><\/span><\/span><\/span>tens\u00e3o total (bateria) \u00e9 a soma das tens\u00f5es parciais \"\" U<\/b><\/span><\/span><\/span>bateria<\/b><\/span><\/span><\/sub><\/span> = U<\/b><\/span><\/span><\/span>L<\/b><\/span><\/span><\/sub><\/span> + U<\/b><\/span><\/span><\/span>dimer<\/b><\/span><\/span><\/sub><\/span> \"\"<\/b><\/span><\/span><\/span> 12 = 10,8 + U<\/b><\/span><\/span><\/span>dimer<\/b><\/span><\/span><\/sub><\/span> \"\" <\/b><\/span><\/span><\/span>U<\/b><\/span><\/span><\/span>dimer<\/b><\/span><\/span><\/sub><\/span> = 1,2 V. <\/b><\/span><\/span><\/span><\/p>\n

Pot\u00eancia no dimer \"\" P<\/b><\/span><\/span><\/span>dimer<\/b><\/span><\/span><\/sub><\/span> = U<\/b><\/span><\/span><\/span>dimer<\/b><\/span><\/span><\/sub><\/span>xi <\/b><\/span><\/span><\/span>= 1,2×1,8 <\/b><\/span><\/span><\/span>= 2,16 W. <\/b><\/span><\/span><\/span><\/p>\n

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

 <\/p>\n

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

Resolu\u00e7\u00e3o comentada das quest\u00f5es de F\u00cdSICA do vestibular da UFMG \u2013 MG \u2013 2017 01- P \u2013 N = como a for\u00e7a exercida pela pista sobre o carro tem intensidade N tal que – N = \u2013 P N = Mg – . R- B 02- Observe na figura a que a for\u00e7a \u00e9 decomposta em duas parcelas e e<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":2823,"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-2825","page","type-page","status-publish","hentry"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/2825","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=2825"}],"version-history":[{"count":2,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/2825\/revisions"}],"predecessor-version":[{"id":2827,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/2825\/revisions\/2827"}],"up":[{"embeddable":true,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/2823"}],"wp:attachment":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/media?parent=2825"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}