{"id":2697,"date":"2017-02-07T03:22:52","date_gmt":"2017-02-07T03:22:52","guid":{"rendered":"http:\/\/fisicaevestibular.com.br\/novo\/?page_id=2697"},"modified":"2024-09-03T17:30:18","modified_gmt":"2024-09-03T17:30:18","slug":"resolucao-comentada-das-questoes-de-fisica-do-vestibular-da-unesp-2017","status":"publish","type":"page","link":"https:\/\/fisicaevestibular.com.br\/novo\/universidades-2017\/unesp-2017\/resolucao-comentada-das-questoes-de-fisica-do-vestibular-da-unesp-2017\/","title":{"rendered":"Resolu\u00e7\u00e3o comentada das quest\u00f5es de F\u00edsica do vestibular da UNESP-2017"},"content":{"rendered":"

Resolu\u00e7\u00e3o comentada das quest\u00f5es de F\u00edsica do vestibular da<\/span><\/span><\/span><\/p>\n

UNESP-2017<\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

02- <\/span><\/span><\/span>As f<\/b><\/span><\/span><\/span>or\u00e7as <\/b><\/span><\/span><\/span>que agem sobre o objeto s\u00e3o <\/b><\/span><\/span><\/span>seu peso \"\"<\/b><\/span><\/span><\/span>(vertical e para baixo) e a <\/b><\/span><\/span><\/span>for\u00e7a de tens\u00e3o (tra\u00e7\u00e3o) \"\" na corda:<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Sendo o <\/b><\/span><\/span><\/span>di\u00e2metro <\/b><\/span><\/span><\/span>do <\/b><\/span><\/span><\/span>arco de circunfer\u00eancia <\/b><\/span><\/span><\/span>percorrido igual a <\/b><\/span><\/span><\/span>d = 15 m<\/b><\/span><\/span><\/span>, o <\/b><\/span><\/span><\/span>raio<\/b><\/span><\/span><\/span> do mesmo ser\u00e1 <\/b><\/span><\/span><\/span>R = \"\"<\/b><\/span><\/span><\/span>= 7,5 m.<\/b><\/span><\/span><\/span><\/p>\n

Decompondo<\/b><\/span><\/span><\/span> a for\u00e7a de <\/b><\/span><\/span><\/span>tra\u00e7\u00e3o \"\"<\/b><\/span><\/span><\/span> em suas <\/b><\/span><\/span><\/span>componentes vertical \"\" e horizontal \"\"<\/b><\/span><\/span><\/span>teremos a <\/b><\/span><\/span><\/span>sequ\u00eancia<\/b><\/span><\/span><\/span> das figuras abaixo:<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

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

\"\"<\/p>\n

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

\"\"<\/p>\n

\"\"<\/p>\n

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

\"\"<\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

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

\"\"<\/p>\n

\"\"<\/p>\n

Os <\/b><\/span><\/span><\/span>pontos<\/b><\/span><\/span><\/span> do <\/b><\/span><\/span><\/span>tubo retil\u00edneo luminescente <\/b><\/span><\/span><\/span>que <\/b><\/span><\/span><\/span>podem ser vistos por pessoas fora da piscina <\/b><\/span><\/span><\/span>s\u00e3o aqueles <\/b><\/span><\/span><\/span>localizados abaixo do ponto M <\/b><\/span><\/span><\/span>j\u00e1 que os <\/b><\/span><\/span><\/span>pontos acima de M ser\u00e3o impedidos de se refratarem pela boia circular opaca.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

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

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

\"\"<\/p>\n

\"\"Os <\/b><\/span><\/span><\/span>sonares emitem e recebem ondas sonoras<\/b><\/span><\/span><\/span>que possuem as <\/b><\/span><\/span><\/span>seguintes carcter\u00edsticas:<\/b><\/span><\/span><\/span><\/p>\n

\"\"S\u00e3o <\/b><\/span><\/span><\/span>ondas mec\u00e2nicas<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>que<\/b><\/span><\/span><\/span>necessitam<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span>de um\u00a0<\/b><\/span><\/span><\/span>meio material<\/b><\/span><\/span><\/span> para se propagar, transportando energia.\u00a0<\/b><\/span><\/span><\/span><\/p>\n

Exemplos: Ondas no mar <\/b><\/span><\/span><\/span>(o meio \u00e9 a \u00e1gua),\u00a0<\/b><\/span><\/span><\/span>ondas sonoras\u00a0<\/b><\/span><\/span><\/span>(o meio pode ser ar, \u00e1gua, etc.),<\/b><\/span><\/span><\/span>ondas em uma corda\u00a0<\/b><\/span><\/span><\/span>(o meio \u00e9 a corda),\u00a0<\/b><\/span><\/span><\/span>etc.<\/b><\/span><\/span><\/span><\/p>\n

Todas <\/b><\/span><\/span><\/span>essas perturba\u00e7\u00f5es <\/b><\/span><\/span><\/span>s\u00e3o <\/b><\/span><\/span><\/span>causadas em <\/b><\/span><\/span><\/span>meios materiais<\/b><\/span><\/span><\/span>.<\/b><\/span><\/span><\/span><\/p>\n

\"\"S\u00e3o ondas longitudinais<\/b><\/span><\/span><\/span>nas quais\u00a0a\u00a0<\/b><\/span><\/span><\/span>dire\u00e7\u00e3o de propaga\u00e7\u00e3o coincide com a dire\u00e7\u00e3o de oscila\u00e7\u00e3o.<\/b><\/span><\/span><\/span><\/p>\n

Exemplos:\u00a0<\/b><\/span><\/span><\/span>ondas<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span>sonoras,<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span>ondas<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span>numa mola,<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>etc.<\/b><\/span><\/span><\/span>\u00a0(<\/b><\/span><\/span>a<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span>membrana do alto falante vibra no eixo x<\/b><\/span><\/span><\/span>, <\/b><\/span><\/span>e as\u00a0<\/b><\/span><\/span><\/span>ondas seguem essa mesma dire\u00e7\u00e3o).<\/b><\/span><\/span><\/span>
\n<\/b><\/span><\/span>\u00a0\"\"\"\"<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"A\u00a0<\/b><\/span><\/span><\/span>frequ\u00eancia<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>\u00e9\u00a0<\/b><\/span><\/span><\/span>caracter\u00edstica da fonte que est\u00e1 emitindo a onda\u00a0<\/b><\/span><\/span><\/span>e<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>independe do meio onde a onda sonora ou eletromagn\u00e9tica estiver se propagando.<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span><\/p>\n

Assim, <\/b><\/span><\/span><\/span>por exemplo,\u00a0<\/b><\/span><\/span><\/span>se uma <\/b><\/span><\/span><\/span>fonte <\/b><\/span><\/span><\/span>emitir uma <\/b><\/span><\/span><\/span>onda (sonora ou luminosa) <\/b><\/span><\/span><\/span>com <\/b><\/span><\/span><\/span>frequ\u00eancia<\/b><\/span><\/span><\/span> f<\/b><\/span><\/span><\/span>num <\/b><\/span><\/span><\/span>dadomeio,<\/b><\/span><\/span><\/span> em <\/b><\/span><\/span><\/span>qualquer outro meio <\/b><\/span><\/span><\/span>que esta onda estiver <\/b><\/span><\/span><\/span>se propagando ela <\/b><\/span><\/span><\/span>ter\u00e1 <\/b><\/span><\/span><\/span>sempre essamesma <\/b><\/span><\/span><\/span>freq\u00fc\u00eancia <\/b><\/span><\/span>f.<\/b><\/span><\/span><\/span><\/p>\n

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

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

Potencial el\u00e9trico V\"\"<\/span><\/span><\/span><\/p>\n

Sendo o <\/b><\/span><\/span><\/span>potencial el\u00e9trico uma grandeza escalar,<\/b><\/span><\/span><\/span> o <\/b><\/span><\/span><\/span>potencial el\u00e9trico no ponto C (V<\/b><\/span><\/span><\/span>C<\/b><\/span><\/span><\/sub><\/span>) <\/b><\/span><\/span><\/span>\u00e9 <\/b><\/span><\/span><\/span>a soma <\/b><\/span><\/span><\/span>dos <\/b><\/span><\/span><\/span>potenciais de cada carga <\/b><\/span><\/span><\/span>(princ\u00edpio da superposi\u00e7\u00e3o) <\/b><\/span><\/span><\/span>nesse ponto equidistante r de cada carga.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

\"\"
\n<\/b><\/span><\/span><\/span>Campo el\u00e9trico gerado num ponto P por v\u00e1rias cargas puntiformes<\/b><\/span><\/span><\/span><\/p>\n

Num\u00a0<\/b><\/span><\/span><\/span>dado ponto P\u00a0<\/b><\/span><\/span><\/span>do espa\u00e7o o\u00a0<\/b><\/span><\/span><\/span>vetor campo el\u00e9trico resultante<\/b><\/span><\/span><\/span>, devido \u00e0\u00a0<\/b><\/span><\/span><\/span>a\u00e7\u00e3o<\/b><\/span><\/span><\/span>\u00a0de\u00a0<\/b><\/span><\/span><\/span>v\u00e1rias cargas,<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

corresponde \u00e0\u00a0<\/b><\/span><\/span><\/span>soma vetorial\u00a0dos campos produzidos por cada uma dessas cargas individualmente.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

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

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

\"\"<\/p>\n

Vamos considerar, na figura, que na <\/b><\/span><\/span><\/span>situa\u00e7\u00e3o inicial a parte do fio semirraspada esteja em contato com o mancal fazendo com que circule corrente pela espira.<\/b><\/span><\/span><\/span><\/p>\n

Considerando tamb\u00e9m que o <\/b><\/span><\/span><\/span>polo A da pilha seja negativo e o <\/b><\/span><\/span><\/span>B<\/b><\/span><\/span><\/span> positivo,<\/b><\/span><\/span><\/span> a <\/b><\/span><\/span><\/span>corrente el\u00e9trica <\/b><\/span><\/span><\/span>fornecida pela <\/b><\/span><\/span><\/span>pilha ir\u00e1 circular no sentido indicado na figura<\/b><\/span><\/span><\/span>, pois a <\/b><\/span><\/span><\/span>corrente i sai do polo positivo e se dirige ao polo negativo.<\/b><\/span><\/span><\/span><\/p>\n

Colocando<\/b><\/span><\/span><\/span> o <\/b><\/span><\/span><\/span>polo Norte na face superior do im\u00e3 o campo magn\u00e9tico \"\" tem dire\u00e7\u00e3o vertical e sentido para cima.<\/b><\/span><\/span><\/span><\/p>\n

<\/a> \"\"Utilizando a <\/b><\/span><\/span><\/span>regra da m\u00e3o esquerda nos ramos superior e inferior (figuras acima) <\/b><\/span><\/span><\/span>voc\u00ea verifica que as for\u00e7as que agem sobre eles fazem a espira girar no sentido hor\u00e1rio.<\/b><\/span><\/span><\/span><\/p>\n

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

Observa\u00e7\u00f5es:<\/b><\/span><\/span><\/span><\/p>\n

\"\" Nos <\/b><\/span><\/span><\/span>dois ramos paralelos \u00e0 \"\" as for\u00e7as s\u00e3o nulas <\/b><\/span><\/span><\/span>pois, <\/b><\/span><\/span><\/span>F = Bilsen(0<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sup><\/span> ou 189<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sup><\/span>) = Bil.0 <\/b><\/span><\/span><\/span>= 0.<\/b><\/span><\/span><\/span><\/p>\n

\"\" A <\/b><\/span><\/span><\/span>extremidade semirraspada impede<\/b><\/span><\/span><\/span> que, a <\/b><\/span><\/span><\/span>corrente,<\/b><\/span><\/span><\/span> ap\u00f3s <\/b><\/span><\/span><\/span>meia volta se inverta, invertend<\/b><\/span><\/span><\/span>o as <\/b><\/span><\/span><\/span>for\u00e7as que podem impedir o giro no sentido hor\u00e1rio.<\/b><\/span><\/span><\/span><\/p>\n

09- <\/span><\/span><\/span>Denominando <\/b><\/span><\/span><\/span>de m<\/b><\/span><\/span><\/span>l<\/b><\/span><\/span><\/sub><\/span> a massa de cada cubo laranja e de m<\/b><\/span><\/span><\/span>a<\/b><\/span><\/span><\/sub><\/span> a massa de cada cubo azul <\/b><\/span><\/span><\/span>e, estando as <\/b><\/span><\/span><\/span>balan\u00e7as em equil\u00edbrio, <\/b><\/span><\/span><\/span>voc\u00ea ter\u00e1:<\/b><\/span><\/span><\/span><\/p>\n

Balan\u00e7a <\/b><\/span><\/span><\/span>da esquerda\"\"2m<\/b><\/span><\/span><\/span>a<\/b><\/span><\/span><\/sub><\/span> + m<\/b><\/span><\/span><\/span>l<\/b><\/span><\/span><\/sub><\/span> = 2 (I)<\/b><\/span><\/span><\/span><\/p>\n

Balan\u00e7a <\/b><\/span><\/span><\/span>da direita \"\"m<\/b><\/span><\/span><\/span>a<\/b><\/span><\/span><\/sub><\/span> + 3 = 2m<\/b><\/span><\/span><\/span>l<\/b><\/span><\/span><\/sub><\/span> (II)<\/b><\/span><\/span><\/span><\/p>\n

Isolando m<\/b><\/span><\/span><\/span>a<\/b><\/span><\/span><\/sub><\/span> em (II) e substituindo em (I<\/b><\/span><\/span><\/span>) \"\"<\/b><\/span><\/span><\/span>m<\/b><\/span><\/span><\/span>a<\/b><\/span><\/span><\/sub><\/span> = 2m<\/b><\/span><\/span><\/span>l<\/b><\/span><\/span><\/sub><\/span> \u2013 3 \"\"2(2m<\/b><\/span><\/span><\/span>l<\/b><\/span><\/span><\/sub><\/span> \u2013 3) + m<\/b><\/span><\/span><\/span>l<\/b><\/span><\/span><\/sub><\/span> = 2 \"\"<\/b><\/span><\/span><\/span> 4m<\/b><\/span><\/span><\/span>l<\/b><\/span><\/span><\/sub><\/span> \u2013 6 + m<\/b><\/span><\/span><\/span>l<\/b><\/span><\/span><\/sub><\/span> = 2 \"\"5m<\/b><\/span><\/span><\/span>l<\/b><\/span><\/span><\/sub><\/span> = 8 \"\"<\/b><\/span><\/span><\/span>m<\/b><\/span><\/span><\/span>l<\/b><\/span><\/span><\/sub><\/span>= 8\/5 <\/b><\/span><\/span><\/span>= 1,6 kg.<\/b><\/span><\/span><\/span><\/p>\n

2m<\/b><\/span><\/span><\/span>a<\/b><\/span><\/span><\/sub><\/span> + 1,6 =2 \"\"<\/b><\/span><\/span><\/span> m<\/b><\/span><\/span><\/span>a<\/b><\/span><\/span><\/sub><\/span> = 0,4\/2 \"\"<\/b><\/span><\/span><\/span>m<\/b><\/span><\/span><\/span>a<\/b><\/span><\/span><\/sub><\/span> = 0,2 kg.<\/b><\/span><\/span><\/span><\/p>\n

Assim, a <\/b><\/span><\/span><\/span>massa de um cubo laranja supera a de um cubo azul <\/b><\/span><\/span><\/span>em <\/b><\/span><\/span><\/span>m<\/b><\/span><\/span><\/span>l<\/b><\/span><\/span><\/sub><\/span> \u2013 m<\/b><\/span><\/span><\/span>a<\/b><\/span><\/span><\/sub><\/span> = 1,6 \u2013 0,2 <\/b><\/span><\/span><\/span>= 1,4 kg.<\/b><\/span><\/span><\/span><\/p>\n

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

 <\/p>\n

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

Resolu\u00e7\u00e3o comentada das quest\u00f5es de F\u00edsica do vestibular da UNESP-2017 02- As for\u00e7as que agem sobre o objeto s\u00e3o seu peso (vertical e para baixo) e a for\u00e7a de tens\u00e3o (tra\u00e7\u00e3o) na corda: Sendo o di\u00e2metro do arco de circunfer\u00eancia percorrido igual a d = 15 m, o raio do mesmo ser\u00e1 R = = 7,5 m. Decompondo a for\u00e7a<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":2695,"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-2697","page","type-page","status-publish","hentry"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/2697","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=2697"}],"version-history":[{"count":4,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/2697\/revisions"}],"predecessor-version":[{"id":3236,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/2697\/revisions\/3236"}],"up":[{"embeddable":true,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/2695"}],"wp:attachment":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/media?parent=2697"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}