{"id":3449,"date":"2017-11-26T11:58:59","date_gmt":"2017-11-26T11:58:59","guid":{"rendered":"http:\/\/fisicaevestibular.com.br\/novo\/?page_id=3449"},"modified":"2024-09-04T12:41:48","modified_gmt":"2024-09-04T12:41:48","slug":"resolucao-comentada-das-questoes-de-fisica-da-uel-2018","status":"publish","type":"page","link":"https:\/\/fisicaevestibular.com.br\/novo\/universidades-2018\/uel-2018\/resolucao-comentada-das-questoes-de-fisica-da-uel-2018\/","title":{"rendered":"Resolu\u00e7\u00e3o comentada das quest\u00f5es de F\u00cdSICA da UEL \u2013 2018"},"content":{"rendered":"

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

UEL \u2013 2018<\/b><\/span><\/span><\/span><\/p>\n

01- <\/b><\/span><\/span><\/span>Se a <\/b><\/span><\/span><\/span>imagem da parte imersa do ovo \u00e9 maior que o objeto,<\/b><\/span><\/span><\/span> a lente <\/b><\/span><\/span><\/span>s\u00f3 pode ser <\/b><\/span><\/span><\/span>convergente<\/b><\/span><\/span><\/span>, <\/b><\/span><\/span><\/span>pois <\/b><\/span><\/span><\/span>lentes divergentes fornecem sempre imagens menores que as do objeto.<\/b><\/span><\/span><\/span><\/p>\n

Os <\/b><\/span><\/span><\/span>raios de luz refletidos, <\/b><\/span><\/span><\/span>que saem da <\/b><\/span><\/span><\/span>parte imersa do ovo <\/b><\/span><\/span><\/span>e que <\/b><\/span><\/span><\/span>chegam<\/b><\/span><\/span><\/span> aos <\/b><\/span><\/span><\/span>olhos <\/b><\/span><\/span><\/span>do <\/b><\/span><\/span><\/span>observador <\/b><\/span><\/span><\/span>sofrem <\/b><\/span><\/span><\/span>refra\u00e7\u00e3o passando da \u00e1gua <\/b><\/span><\/span><\/span>(meio mais refringente, maior \u00edndice de refra\u00e7\u00e3o) <\/b><\/span><\/span><\/span>para o ar <\/b><\/span><\/span><\/span>(menor \u00edndice de refra\u00e7\u00e3o), se <\/b><\/span><\/span><\/span>afastando da normal, <\/b><\/span><\/span><\/span>fazendo com que o <\/b><\/span><\/span><\/span>observador enxergue a imagem maior que o objeto.<\/b><\/span><\/span><\/span><\/p>\n

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

02- <\/b><\/span><\/span><\/span>a)<\/b><\/span><\/span><\/span> <\/b>Falsa \"\"<\/b><\/span><\/span><\/span> Quando um corpo se <\/b><\/span><\/span><\/span>movimenta em rela\u00e7\u00e3o a outro<\/b><\/span><\/span><\/span>, a for\u00e7a de <\/b><\/span><\/span><\/span>atrito aparece sempre <\/b><\/span><\/span><\/span>no <\/b><\/span><\/span><\/span>sentido contr\u00e1rio <\/b><\/span><\/span><\/span>ao <\/b><\/span><\/span><\/span>movimento ou \u00e0 tend\u00eancia de movimento.<\/b><\/span><\/span><\/span><\/p>\n

b) <\/b><\/span><\/span><\/span>Falsa \"\" <\/b><\/span><\/span><\/span>A <\/b><\/span><\/span><\/span>for\u00e7a de atrito est\u00e1tico m\u00e1xima <\/b><\/span><\/span><\/span>\u00e9 fornecida por<\/b><\/span><\/span><\/span> <\/b>F<\/b><\/span><\/span><\/span>atmax<\/b><\/span><\/span><\/sub><\/span> = \u00b5emgcos\u03b8 <\/b><\/span><\/span><\/span>e n\u00e3o F<\/b><\/span><\/span><\/span>atmax<\/b><\/span><\/span><\/sub><\/span> = \u00b5emgsen\u03b8.<\/b><\/span><\/span><\/span><\/p>\n

Veja teoria abaixo:<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

d) <\/b><\/span><\/span>Correta<\/b><\/span><\/span> \"\" <\/b><\/span><\/span>Leis emp\u00edricas do atrito<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"\"\u00a0\u201c<\/span>A for\u00e7a de atrito se\u00a0<\/b><\/span><\/span>op\u00f5e ao movimento<\/b><\/span><\/span>\u00a0de um corpo que desliza apoiado sobre um plano\u201d.<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"\"\u00a0\u201cA for\u00e7a de atrito se op\u00f5e \u00e0\u00a0<\/b><\/span><\/span>tend\u00eancia ao movimento<\/b><\/span><\/span>\u00a0de um corpo apoiado sobre um plano\u201d.<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"\"\u00a0\u201cA for\u00e7a de atrito \u00e9\u00a0<\/b><\/span><\/span>proporcional a for\u00e7a normal (\"\")<\/b><\/span><\/span>\u00a0que \u00a0o plano exerce sobre o corpo, ou seja,\u00a0\"\"\u00a0= \u03bc.\"\"\u00a0\u201d.<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"\u00a0<\/span>\u201cA intensidade da for\u00e7a de atrito, dentro de certos limites\u00a0<\/b><\/span><\/span>n\u00e3o depende da \u00e1rea aparente de contato\u201d<\/b><\/span><\/span><\/span><\/span><\/p>\n

e) Falsa \"\" Veja teoria abaixo:<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

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

03- <\/b><\/span><\/span><\/span>(a) Falsa \"\" Se a massa espec\u00edfica do aparelho de TV fosse maior que a massa espec\u00edfica da lama, a TV afundaria.<\/b><\/span><\/span><\/span><\/p>\n

(b) Falsa \"\" O volume de lama deslocado \u00e9 igual ao volume da parte imersa do aparelho de TV. <\/b><\/span><\/span><\/span><\/p>\n

(c) Correta \"\" <\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Como o <\/b><\/span><\/span><\/span>aparelho de TV est\u00e1 flutuando parcialmente imerso na lama,<\/b><\/span><\/span><\/span> a <\/b><\/span><\/span><\/span>for\u00e7a resultante<\/b><\/span><\/span><\/span> sobre ele \u00e9 <\/b><\/span><\/span><\/span>nula<\/b><\/span><\/span><\/span> e assim, o <\/b><\/span><\/span><\/span>m\u00f3dulo do peso da TV deve anular o m\u00f3dulo do empuxo.<\/b><\/span><\/span><\/span><\/p>\n

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

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

\"\"<\/p>\n

\"\"<\/p>\n

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

Veja teoria a seguir:<\/b><\/span><\/span><\/span><\/p>\n

\u00a0Pode-se\u00a0<\/b><\/span><\/span><\/span>interligar duas ou mais\u00a0 polias atrav\u00e9s de uma correia<\/b><\/span><\/span><\/span> (figura 1) ou <\/b><\/span><\/span><\/span>acoplar duas ou mais engrenagens (figura 2)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Todos os pontos da correia\u00a0<\/b><\/span><\/span><\/span>(admitidos inextens\u00edveis) t\u00eam a\u00a0<\/b><\/span><\/span><\/span>mesma velocidade escalar V <\/b><\/span><\/span><\/span>que todos <\/b><\/span><\/span><\/span>os pontos da periferia de cada polia, <\/b><\/span><\/span><\/span>desde que <\/b><\/span><\/span><\/span>n\u00e3o ocorra deslizamento.<\/b><\/span><\/span><\/span><\/p>\n

O <\/b><\/span><\/span><\/span>mesmo ocorre <\/b><\/span><\/span><\/span>com <\/b><\/span><\/span><\/span>todos\u00a0os dentes da polia engrenada<\/b><\/span><\/span><\/span>, que tem a <\/b><\/span><\/span><\/span>mesma\u00a0velocidade escalar V.<\/b><\/span><\/span><\/span><\/p>\n

Assim,\u00a0<\/b><\/span><\/span><\/span>V<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>\u00a0= V<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>\u00a0\u00a0\"\"<\/b><\/span><\/span><\/span>\u00a0W<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>.R<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>\u00a0= W<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>.R<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>\u00a0\u00a0\"\"\u00a0\u00a0(2\u03c0\/T<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>).R<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>= (2\u03c0\/T<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>).R<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>\u00a0\u00a0\"\"\u00a0mas, f = 1\/T\u00a0\"\"\u00a0 \u00a02\u03c0f<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>.R<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>\u00a0=\u00a0 2\u03c0f<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>.R<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>\u00a0\u00a0<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Sendo os <\/b><\/span><\/span><\/span>dentes de cada engrenagem iguais, <\/b><\/span><\/span><\/span>o <\/b><\/span><\/span><\/span>raio de cada uma \u00e9 proporcional ao n\u00famero de dentes.<\/b><\/span><\/span><\/span> Assim, <\/b><\/span><\/span><\/span>R<\/b><\/span><\/span><\/span>A<\/b><\/span><\/span><\/sub><\/span> = 200 dentes, R<\/b><\/span><\/span><\/span>B<\/b><\/span><\/span><\/sub><\/span> = 20 dentes<\/b><\/span><\/span><\/span> e <\/b><\/span><\/span><\/span>R<\/b><\/span><\/span><\/span>c<\/b><\/span><\/span><\/sub><\/span> = 100 dentes.<\/b><\/span><\/span><\/span><\/p>\n

f<\/b><\/span><\/span><\/span>A<\/b><\/span><\/span><\/sub><\/span> = 40 rpm e f<\/b><\/span><\/span><\/span>B<\/b><\/span><\/span><\/sub><\/span> = ? \"\"<\/b><\/span><\/span><\/span> <\/b>A com B<\/b><\/span><\/span><\/span> \"\" <\/b><\/span><\/span><\/span>f<\/b><\/span><\/span><\/span>A<\/b><\/span><\/span><\/sub><\/span>.R<\/b><\/span><\/span><\/span>A<\/b><\/span><\/span><\/sub><\/span> = f<\/b><\/span><\/span><\/span>B<\/b><\/span><\/span><\/sub><\/span>.R<\/b><\/span><\/span><\/span>B<\/b><\/span><\/span><\/sub><\/span> \"\"<\/b><\/span><\/span><\/span> 40.200 = f<\/b><\/span><\/span><\/span>B<\/b><\/span><\/span><\/sub><\/span>.20 \"\" f<\/b><\/span><\/span><\/span>B<\/b><\/span><\/span><\/sub><\/span> = 8000\/20 \"\" <\/b><\/span><\/span><\/span>f<\/b><\/span><\/span><\/span>B<\/b><\/span><\/span><\/sub><\/span> = 400 Hz (como a A gira no sentido anti-hor\u00e1rio, a B girar\u00e1 no sentido hor\u00e1rio).<\/b><\/span><\/span><\/span><\/p>\n

B com C \"\" f<\/b><\/span><\/span><\/span>B<\/b><\/span><\/span><\/sub><\/span>.R<\/b><\/span><\/span><\/span>B<\/b><\/span><\/span><\/sub><\/span> = f<\/b><\/span><\/span><\/span>C<\/b><\/span><\/span><\/sub><\/span>.R<\/b><\/span><\/span><\/span>C<\/b><\/span><\/span><\/sub><\/span> \"\"<\/b><\/span><\/span><\/span> 400.20 = f<\/b><\/span><\/span><\/span>C<\/b><\/span><\/span><\/sub><\/span>.100 \"\" f<\/b><\/span><\/span><\/span>C<\/b><\/span><\/span><\/sub><\/span> = 8000\/100 \"\" <\/b><\/span><\/span><\/span>f<\/b><\/span><\/span><\/span>C<\/b><\/span><\/span><\/sub><\/span> = 80 Hz (como a B gira no sentido hor\u00e1rio, a C girar\u00e1 no sentido anti-hor\u00e1rio).<\/b><\/span><\/span><\/span><\/p>\n

R- D<\/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 da UEL \u2013 2018 01- Se a imagem da parte imersa do ovo \u00e9 maior que o objeto, a lente s\u00f3 pode ser convergente, pois lentes divergentes fornecem sempre imagens menores que as do objeto. Os raios de luz refletidos, que saem da parte imersa do ovo e que chegam aos olhos do observador<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":3447,"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-3449","page","type-page","status-publish","hentry"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/3449","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=3449"}],"version-history":[{"count":2,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/3449\/revisions"}],"predecessor-version":[{"id":3451,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/3449\/revisions\/3451"}],"up":[{"embeddable":true,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/3447"}],"wp:attachment":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/media?parent=3449"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}