{"id":1660,"date":"2015-12-19T15:07:40","date_gmt":"2015-12-19T15:07:40","guid":{"rendered":"http:\/\/fisicaevestibular.com.br\/novo\/?page_id=1660"},"modified":"2024-09-03T13:59:21","modified_gmt":"2024-09-03T13:59:21","slug":"resolucao-da-unesp-primeira-fase-2016","status":"publish","type":"page","link":"https:\/\/fisicaevestibular.com.br\/novo\/universidades-2016\/unesp-primeira-fase-2016\/resolucao-da-unesp-primeira-fase-2016\/","title":{"rendered":"Resolu\u00e7\u00e3o da Unesp – Primeira fase \u2013 2016"},"content":{"rendered":"

Exerc\u00edcios da UNESP\/2016 com resolu\u00e7\u00e3o comentada<\/b><\/span><\/span><\/span><\/p>\n

01- <\/span><\/span><\/span>Veja a figura abaixo:<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

 <\/p>\n

\"\"<\/p>\n

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

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

\"\"<\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

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

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

\"\"<\/p>\n

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

04- <\/span><\/span><\/span>Energia mec\u00e2nica (E<\/b><\/span><\/span>m<\/b><\/span><\/sub><\/span>) \"\"<\/b><\/span><\/span>\u00a0 \u00e9 a <\/b><\/span><\/span>energia total<\/b><\/span><\/span> do sistema, ou seja, a <\/b><\/span><\/span>soma das energias cin\u00e9tica<\/b><\/span><\/span> <\/b>(E<\/b><\/span><\/span>c<\/b><\/span><\/sub><\/span>) com a energia potencial (E<\/b><\/span><\/span>p<\/b><\/span><\/sub><\/span>), sendo que esta pode ser energia <\/b><\/span><\/span>potencial gravitacional ou energia potencial el\u00e1stica, ou ambas.<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"\"Sistemas conservativos<\/b><\/span><\/span> \"\"\u00a0<\/b><\/span><\/span>S\u00e3o aqueles onde <\/b><\/span><\/span><\/span>n\u00e3o ocorre dissipa\u00e7\u00e3o de energia<\/b><\/span><\/span><\/span> e onde a <\/b><\/span><\/span><\/span>energia<\/b><\/span><\/span><\/span> <\/b>cin\u00e9tica (E<\/b><\/span><\/span><\/span>c<\/b><\/span><\/span><\/sub><\/span>) e a energia potencial (E<\/b><\/span><\/span><\/span>p<\/b><\/span><\/span><\/sub><\/span>) s\u00e3o vari\u00e1veis,<\/b><\/span><\/span><\/span> mas <\/b><\/span><\/span><\/span>sua soma,<\/b><\/span><\/span><\/span> que \u00e9 a <\/b><\/span><\/span><\/span>energia mec\u00e2nica \u00e9<\/b><\/span><\/span><\/span> <\/b>constante<\/b><\/span><\/span><\/span> (\u00e9 sempre a mesma em cada ponto), desde que o corpo se mova sob <\/b><\/span><\/span><\/span>a\u00e7\u00e3o de for\u00e7as\u00a0conservativas\u00a0(for\u00e7a peso, el\u00e1stica, el\u00e9trica, etc.).<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

Agora podemos determinar o m\u00f3dulo da<\/b><\/span><\/span> quantidade de movimento do golfinho no ponto B:<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

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

 <\/p>\n

05- <\/b><\/span><\/span><\/span>A\u00a0<\/b><\/span><\/span><\/span>transforma\u00e7\u00e3o adiab\u00e1tica<\/b><\/span><\/span><\/span> \u00e9 aquela\u00a0em que <\/b><\/span><\/span><\/span>n\u00e3o h\u00e1 trocas\u00a0de energia t\u00e9rmica (calor) entre o sistema e o meio exterior, por ser muito r\u00e1pida.<\/b><\/span><\/span><\/span><\/p>\n

No <\/b><\/span><\/span><\/span>decorrer da subida<\/b><\/span><\/span><\/span>, ocorre uma <\/b><\/span><\/span><\/span>EXPANS\u00c3O ADIAB\u00c1TICA, (sem trocas de calor com o meio exterior),<\/b><\/span><\/span><\/span> pois o ar <\/b><\/span><\/span><\/span>quente se expande muito<\/b><\/span><\/span><\/span> <\/b>rapidamente<\/b><\/span><\/span><\/span> e, devido a isso, <\/b><\/span><\/span><\/span>calor (Q) trocado entre o sistema e o meio exterior \u00e9 nulo (Q = 0).<\/b><\/span><\/span><\/span><\/p>\n

Aplicando a <\/b><\/span><\/span><\/span>primeira lei da termodin\u00e2mica,<\/b><\/span><\/span><\/span> temos \"\" <\/b><\/span><\/span><\/span>\uf044<\/b><\/span><\/span><\/span>U = Q \u2013 W \"\" <\/b><\/span><\/span><\/span>\uf044<\/b><\/span><\/span><\/span>U = 0 \u2013 W \"\" <\/b><\/span><\/span><\/span>\uf044<\/b><\/span><\/span><\/span>U = \u2013 W.<\/b><\/span><\/span><\/span><\/p>\n

Assim, quando um g\u00e1s se <\/b><\/span><\/span><\/span>expande adiabaticamente<\/b><\/span><\/span><\/span>, a <\/b><\/span><\/span><\/span>varia\u00e7\u00e3o de energia interna \u00e9 negativa (<\/b><\/span><\/span><\/span>\uf044<\/b><\/span><\/span><\/span>U <\/b><\/span><\/span><\/span>\uf03c<\/b><\/span><\/span><\/span> <\/b>0)<\/b><\/span><\/span><\/span> o que provoca o <\/b><\/span><\/span><\/span>resfriamento do g\u00e1s (ar).<\/b><\/span><\/span><\/span><\/p>\n

Observe que, <\/b><\/span><\/span><\/span>se <\/b><\/span><\/span><\/span>\uf044<\/b><\/span><\/span><\/span>U <\/b><\/span><\/span><\/span>\uf03c<\/b><\/span><\/span><\/span> 0, <\/b><\/span><\/span><\/span>o <\/b><\/span><\/span><\/span>trabalho W ser\u00e1 positivo<\/b><\/span><\/span><\/span> o que provoca uma <\/b><\/span><\/span><\/span>expans\u00e3o do ar (g\u00e1s).<\/b><\/span><\/span><\/span><\/p>\n

Quando <\/b><\/span><\/span><\/span>temos altas altitudes<\/b><\/span><\/span><\/span>, temos <\/b><\/span><\/span><\/span>pouca absor\u00e7\u00e3o da radia\u00e7\u00e3o emitida pelo sol,<\/b><\/span><\/span><\/span> devido
\n<\/b><\/span><\/span><\/span>\u00e0 superf\u00edcie ser montanhosa.<\/b><\/span><\/span><\/span><\/b><\/p>\n

A temperatura <\/b><\/span><\/span><\/span>diminui com a altitude<\/b><\/span><\/span><\/span> porque o <\/b><\/span><\/span><\/span>aquecimento se d\u00e1 a partir da superf\u00edcie terrestre<\/b><\/span><\/span><\/span>. \u00c9 que do <\/b><\/span><\/span><\/span>total de energia que chega do Sol, <\/b><\/span><\/span><\/span>apenas 19% s\u00e3o retidos pelo ar; 34% acabam refletidos de volta. <\/b><\/span><\/span><\/span>S\u00e3o os 47% restantes, retidos pela parte s\u00f3lida do planeta, que passam calor \u00e0 atmosfera.<\/b><\/span><\/span><\/span><\/p>\n

Portanto, o <\/b><\/span><\/span><\/span>topo <\/b><\/span><\/span><\/span>da montanha est\u00e1 <\/b><\/span><\/span><\/span>mais distante da superf\u00edcie,<\/b><\/span><\/span><\/span> que <\/b><\/span><\/span><\/span>reflete quase toda a radia\u00e7\u00e3o solar sob<\/b><\/span><\/span><\/span> <\/b>forma de calor.<\/b><\/span><\/span><\/span> A <\/b><\/span><\/span><\/span>radia\u00e7\u00e3o solar incidente \u00e9 inclinada nas encostas<\/b><\/span><\/span><\/span>, ocorrendo <\/b><\/span><\/span><\/span>menor absor\u00e7\u00e3o em rela\u00e7\u00e3o a base da montanha.<\/b><\/span><\/span><\/span><\/p>\n

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

06- <\/b><\/span><\/span><\/span>Sabendo que o <\/b><\/span><\/span><\/span>rapaz se posicionou sempre a mesma dist\u00e2ncia<\/b><\/span><\/span><\/span> desses espelhos, <\/b><\/span><\/span><\/span>enxergando tr\u00eas<\/b><\/span><\/span><\/span> <\/b>diferentes imagens de seu rosto,<\/b><\/span><\/span><\/span> por compara\u00e7\u00e3o conseguimos identificar cada espelho:<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Espelho convexo<\/b><\/span><\/span><\/span> \"\" <\/b><\/span><\/span><\/span>Para qualquer<\/b><\/span><\/span><\/span> localiza\u00e7\u00e3o do objeto<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Para qualquer posi\u00e7\u00e3o do objeto, a <\/b><\/span><\/span><\/span>imagem ter\u00e1 sempre:<\/b><\/span><\/span><\/span><\/p>\n

Natureza <\/b><\/span><\/span><\/span>\u2013 virtual<\/b><\/span><\/span><\/span><\/p>\n

Localiza\u00e7\u00e3o <\/b><\/span><\/span><\/span>\u2013 atr\u00e1s <\/b><\/span><\/span><\/span>do espelho e entre V e F <\/b><\/span><\/span><\/span>e observe que \u00e0 medida que o objeto se aproxima do espelho, a imagem tamb\u00e9m se aproxima e aumenta de tamanho, mas est\u00e1 sempre entre V e F..<\/b><\/span><\/span><\/span><\/p>\n

Tamanho <\/b><\/span><\/span><\/span>\u2013 <\/b><\/span><\/span><\/span>menor<\/b><\/span><\/span><\/span> que o do objeto<\/b><\/span><\/span><\/span><\/p>\n

Orienta\u00e7\u00e3o <\/b><\/span><\/span><\/span>\u2013 <\/b><\/span><\/span><\/span>direita<\/b><\/span><\/span><\/span> em rela\u00e7\u00e3o ao objeto<\/b><\/span><\/span><\/span><\/p>\n

Utilidades:<\/b><\/span><\/span><\/span> Os <\/b><\/span><\/span><\/span>espelhos convexos<\/b><\/span><\/span><\/span> s\u00e3o empregados <\/b><\/span><\/span><\/span>como retrovisores em ve\u00edculos, cabines de<\/b><\/span><\/span><\/span> <\/b>seguran\u00e7a, elevadores, etc.<\/b><\/span><\/span><\/span> Sua vantagem sobre o espelho plano, nesse particular, \u00e9 ter maior campo visual. T\u00eam, entretanto, o inconveniente de n\u00e3o darem no\u00e7\u00e3o da dist\u00e2ncia.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

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

 <\/p>\n

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

\"\"<\/p>\n

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

 <\/p>\n

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

\"\"<\/p>\n

B)<\/b><\/span><\/span><\/span> \u00e9 <\/b><\/span><\/span><\/span>mais econ\u00f4mico<\/b><\/span><\/span><\/span> usarmos em <\/b><\/span><\/span><\/span>nossas resid\u00eancias correntes el\u00e9tricas<\/b><\/span><\/span><\/span> sob <\/b><\/span><\/span><\/span>tens\u00e3o de 110 V<\/b><\/span><\/span><\/span> do que <\/b><\/span><\/span><\/span>de 220 V.<\/b><\/span><\/span><\/span><\/p>\n

B) ERRADA \"\" <\/b><\/span><\/span><\/span>Exemplo pr\u00e1tico<\/b><\/span><\/span><\/span> \"\" considere um <\/b><\/span><\/span><\/span>chuveiro el\u00e9trico de pot\u00eancia P = 4400 W.<\/b><\/span><\/span><\/span> Quando ligado em <\/b><\/span><\/span><\/span>U<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>= 220 V,<\/b><\/span><\/span><\/span> a <\/b><\/span><\/span><\/span>corrente el\u00e9trica<\/b><\/span><\/span><\/span> por ele consumida ser\u00e1 P = U<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>.i<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span> \"\" 4400 = 220.i<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span><\/b><\/p>\n

\"\" i<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span> <\/b>= 4400\/220 <\/b><\/span><\/span><\/span>= 20 A.<\/b><\/span><\/span><\/span><\/p>\n

O <\/b><\/span><\/span><\/span>mesmo chuveiro de P = 4400 W<\/b><\/span><\/span><\/span> quando ligado em <\/b><\/span><\/span><\/span>U<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span> = 110 V<\/b><\/span><\/span><\/span> ser\u00e1 percorrido por <\/b><\/span><\/span><\/span>i<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span> <\/b>= 4400\/110 <\/b><\/span><\/span><\/span>= 40 A (menor corrente que quando ligado em 110 V).<\/b><\/span><\/span><\/span><\/p>\n

Menor corrente el\u00e9trica, menor consumo de energia para a mesma pot\u00eancia<\/b><\/span><\/span><\/span>, ent\u00e3o <\/b><\/span><\/span><\/span>ligado em 220 V o consumo ser\u00e1 menor sendo mais econ\u00f4mico.<\/b><\/span><\/span><\/span><\/p>\n

Isso ocorre, pois a <\/b><\/span><\/span><\/span>pot\u00eancia dissipada por efeito Joule \u00e9 menor quando ele \u00e9 ligado em 220 V<\/b><\/span><\/span><\/span> (menor corrente i), pois, pelo enunciado, <\/b><\/span><\/span><\/span>as <\/b><\/span><\/span><\/span>perdas de energia<\/b><\/span><\/span><\/span> que ocorrem por efeito joule (aquecimento em virtude da resist\u00eancia R) s\u00e3o medidas por <\/b><\/span><\/span><\/span>\u2206E = R\u00b7i<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sup><\/span>\u00b7\u2206t,<\/b><\/span><\/span><\/span> onde <\/b><\/span><\/span><\/span>R <\/b><\/span><\/span><\/span>e <\/b><\/span><\/span><\/span>\u2206t<\/b><\/span><\/span><\/span> s\u00e3o constantes e, nesse caso, como <\/b><\/span><\/span><\/span>i<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sup><\/span> \u00e9 diretamente proporcional \u00e0 perda de energia \u2206E,<\/b><\/span><\/span><\/span> <\/b>menor corrente (U = 220 V) implicar\u00e1 em menor perda de energia.<\/b><\/span><\/span><\/span><\/p>\n

(C)<\/b><\/span><\/span><\/span> em um <\/b><\/span><\/span><\/span>mesmo intervalo de tempo<\/b><\/span><\/span><\/span>, a <\/b><\/span><\/span><\/span>energia el\u00e9trica consumida<\/b><\/span><\/span><\/span> por um <\/b><\/span><\/span><\/span>aparelho el\u00e9trico<\/b><\/span><\/span><\/span> varia <\/b><\/span><\/span><\/span>inversamente com a pot\u00eancia<\/b><\/span><\/span><\/span> desse aparelho.<\/b><\/span><\/span><\/span><\/p>\n

C) ERRADA \"\" <\/b><\/span><\/span><\/span>Pelo enunciado \"\" E = V.i.<\/b><\/span><\/span><\/span>\u2206t \"\" <\/b><\/span><\/span><\/span>E = P.<\/b><\/span><\/span><\/span> <\/b>\u2206t<\/b><\/span><\/span><\/span> \"\" \u2206t =E\/P \"\" <\/b><\/span><\/span><\/span>no <\/b><\/span><\/span><\/span>mesmo intervalo<\/b><\/span><\/span><\/span> de <\/b><\/span><\/span><\/span>tempo, <\/b><\/span><\/span><\/span>a energia consumida \u00e9 diretamente proporcional \u00e0 pot\u00eancia.<\/b><\/span><\/span><\/p>\n

(D)<\/b><\/span><\/span><\/span> uma <\/b><\/span><\/span><\/span>poss\u00edvel unidade de medida de energia el\u00e9trica \u00e9 o kV\u00b7A<\/b><\/span><\/span><\/span> <\/b>(quilovolt-amp\u00e8re),<\/b><\/span><\/span><\/span> que pode, portanto, ser <\/b><\/span><\/span><\/span>convertida para a unidade correspondente do Sistema Internacional, o joule.<\/b><\/span><\/span><\/span><\/p>\n

D<\/b><\/span><\/span>)<\/b><\/span><\/span><\/span> ERRADA \"\" <\/b><\/span><\/span><\/span>Pelo enunciado \"\" E = V.i.<\/b><\/span><\/span><\/span>\u2206t \"\" <\/b><\/span><\/span><\/span>substituindo as unidades de medida, <\/b><\/span><\/span><\/span>temos \"\"<\/b><\/span><\/span><\/span><\/p>\n

E = V.i.\u2206t = kV.A.s<\/b><\/span><\/span><\/span><\/p>\n

E)<\/b><\/span><\/span><\/span> para um <\/b><\/span><\/span><\/span>valor constante de tens\u00e3o el\u00e9trica (V)<\/b><\/span><\/span><\/span>, a <\/b><\/span><\/span><\/span>intensidade de corrente (i)<\/b><\/span><\/span><\/span> que atravessa um condutor ser\u00e1 <\/b><\/span><\/span><\/span>tanto maior quanto maior for a \u00e1rea de sua sec\u00e7\u00e3o transversal.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

 <\/p>\n

Voltar para os exerc\u00edcios<\/a>\u00a0<\/span><\/h3>\n","protected":false},"excerpt":{"rendered":"

Exerc\u00edcios da UNESP\/2016 com resolu\u00e7\u00e3o comentada 01- Veja a figura abaixo:   R- D 02- Pode-se\u00a0interligar duas ou mais\u00a0 polias atrav\u00e9s de uma correia (figura 1) ou acoplar duas ou mais engrenagens (figura 2) R- A 03- R- C 04- Energia mec\u00e2nica (Em) \u00a0 \u00e9 a energia total do sistema, ou seja, a soma das energias cin\u00e9tica (Ec) com a<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":1658,"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-1660","page","type-page","status-publish","hentry"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/1660","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=1660"}],"version-history":[{"count":2,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/1660\/revisions"}],"predecessor-version":[{"id":1662,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/1660\/revisions\/1662"}],"up":[{"embeddable":true,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/1658"}],"wp:attachment":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/media?parent=1660"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}