{"id":725,"date":"2015-05-12T19:30:38","date_gmt":"2015-05-12T19:30:38","guid":{"rendered":"http:\/\/fisicaevestibular.com.br\/novo\/?page_id=725"},"modified":"2024-09-03T13:13:26","modified_gmt":"2024-09-03T13:13:26","slug":"resolucao-comentada-da-unisinos-2015","status":"publish","type":"page","link":"https:\/\/fisicaevestibular.com.br\/novo\/universidades-2015\/exercicios-resolvidos-da-unisinos\/resolucao-comentada-da-unisinos-2015\/","title":{"rendered":"Resolu\u00e7\u00e3o Comentada da UNISINOS 2015"},"content":{"rendered":"

RESOLU\u00c7\u00d5ES<\/span><\/span><\/span><\/p>\n

01- <\/span><\/span><\/span>Tempo que o som, com velocidade de V<\/b><\/span><\/span>s<\/b><\/span><\/span><\/sub> = 340 m\/s demorou para ir de Fred at\u00e9 Hulk, percorrendo d=340m \"\" V<\/b><\/span><\/span>s<\/b><\/span><\/span><\/sub> = d\/t\u2019 \"\" 340 = 340\/t\u2019 \"\" t\u2019 = 1s.<\/b><\/span><\/span><\/p>\n

Nesse tempo <\/b><\/span><\/span>t\u2019 = 1s<\/b><\/span><\/span><\/span> o carro com velocidade <\/b><\/span><\/span>V<\/b><\/span><\/span><\/span>c<\/b><\/span><\/span><\/sub><\/span> percorreu uma dist\u00e3ncia x<\/b><\/span><\/span><\/span> tal que \"\" V<\/b><\/span><\/span>c<\/b><\/span><\/span><\/sub> = x\/t\u2019 \"\" V<\/b><\/span><\/span>c<\/b><\/span><\/span><\/sub> =<\/b><\/span><\/span><\/p>\n

x\/1 \"\" <\/b><\/span><\/span>V<\/b><\/span><\/span><\/span>c<\/b><\/span><\/span><\/sub><\/span> = x (I).<\/b><\/span><\/span><\/span><\/p>\n

Quando ouviu o som do apito<\/b><\/span><\/span><\/span> e com o <\/b><\/span><\/span>carro na posi\u00e7\u00e3o x<\/b><\/span><\/span><\/span>, Hulk <\/b><\/span><\/span>disparou <\/b><\/span><\/span><\/span>o cron\u00f4metro e o <\/b><\/span><\/span>desligou <\/b><\/span><\/span><\/span>quando o <\/b><\/span><\/span>carro passou por ele marcando 12,6s<\/b><\/span><\/span><\/span>, portanto o carro <\/b><\/span><\/span>percorreu uma dist\u00e2ncia de d\u2019 = 340 \u2013 x em t = 12,6s.<\/b><\/span><\/span><\/span><\/p>\n

V<\/b><\/span><\/span><\/span>c<\/b><\/span><\/span><\/span><\/sub> = d\u2019\/t \"\" <\/b><\/span><\/span><\/span>V<\/b><\/span><\/span><\/span><\/span>c<\/b><\/span><\/span><\/span><\/sub><\/span> = (340 \u2013 x)\/12.6 (II)<\/b><\/span><\/span><\/span><\/span><\/p>\n

Igualando (I) com (II) \"\" x = (340 \u2013 x)\/12,6 \"\" 12,6x = 340 \u2013 x \"\" <\/b><\/span><\/span><\/span>x <\/b><\/span><\/span><\/span>= 340\/13,6 <\/b><\/span><\/span><\/span>= 25m<\/b><\/span><\/span><\/span>.<\/b><\/span><\/span><\/span><\/p>\n

Substituindo <\/b><\/span><\/span>x = 25m em (I<\/b><\/span><\/span><\/span>) \"\" <\/b><\/span><\/span>V<\/b><\/span><\/span><\/span>c<\/b><\/span><\/span><\/sub><\/span> =<\/b><\/span><\/span><\/span> x = <\/b><\/span><\/span>25m\/s.<\/b><\/span><\/span><\/span><\/p>\n

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

02- <\/span><\/span><\/span>No <\/b><\/span><\/span>instante em que a luz deixa de iluminar<\/b><\/span><\/span><\/span> o fundo do tanque, o raio de luz refratado no interior do l\u00edquido <\/b><\/span><\/span>atinge o lado esquerdo de sua base<\/b><\/span><\/span><\/span>.<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

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

03- <\/span><\/span><\/span>Figura 1<\/b><\/span><\/span><\/span> \"\" A e C se <\/b><\/span><\/span>atraem<\/b><\/span><\/span><\/span> \"\" ou <\/b><\/span><\/span>uma est\u00e1 neutra e a outra eletrizada,<\/b><\/span><\/span><\/span> ou ambas est\u00e3o eletrizadas <\/b><\/span><\/span>com cargas de sinais opostos<\/b><\/span><\/span><\/span>.<\/b><\/span><\/span><\/p>\n

Figura 2<\/b><\/span><\/span><\/span> \"\" B e C se atraem \"\" ou <\/b><\/span><\/span>uma est\u00e1 neutra e a outra eletrizada,<\/b><\/span><\/span><\/span> ou ambas est\u00e3o eletrizadas <\/b><\/span><\/span>com cargas de sinais opostos<\/b><\/span><\/span><\/span>.<\/b><\/span><\/span><\/p>\n

Figura 3<\/b><\/span><\/span><\/span> \"\" A e B se atraem \"\" ou <\/b><\/span><\/span>uma est\u00e1 neutra e a outra eletrizada,<\/b><\/span><\/span><\/span> ou ambas est\u00e3o eletrizadas <\/b><\/span><\/span>com cargas de sinais opostos<\/b><\/span><\/span><\/span>.<\/b><\/span><\/span><\/p>\n

Observe nos experimentos que <\/b><\/span><\/span><\/span>as esferas A e B est\u00e3o eletrizadas com cargas de sinais contr\u00e1rios<\/b><\/span><\/span><\/span> (pois se <\/b><\/span><\/span><\/span>atraem no experimento 3<\/b><\/span><\/span><\/span>) e que a <\/b><\/span><\/span><\/span>esfera C est\u00e1 neutra<\/b><\/span><\/span><\/span>, sendo <\/b><\/span><\/span><\/span>atra\u00edda por indu\u00e7\u00e3o<\/b><\/span><\/span><\/span> pela <\/b><\/span><\/span><\/span>esfera<\/b><\/span><\/span><\/span> <\/b>A<\/b><\/span><\/span><\/span> (experimento 1) e <\/b><\/span><\/span><\/span>pela esfera B<\/b><\/span><\/span><\/span> (experimento 2). Assim, das tr\u00eas hip\u00f3teses apresentadas, a <\/b><\/span><\/span><\/span>correta<\/b><\/span><\/span><\/span> \u00e9 a <\/b><\/span><\/span><\/span>hip\u00f3tese III.<\/b><\/span><\/span><\/span><\/p>\n

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

04- <\/span><\/span><\/span>I. Falsa<\/b><\/span><\/span><\/span> \"\" <\/b><\/span><\/span>Garrafa t\u00e9rmica\u00a0<\/b><\/span><\/span>\u2013 H\u00e1 aproximadamente um s\u00e9culo, foi inventada por James Dewar e foi constru\u00edda de maneira que evite a transmiss\u00e3o de calor pelos tr\u00eas processos (condu\u00e7\u00e3o, convec\u00e7\u00e3o e <\/b><\/span><\/span>irradia\u00e7\u00e3o<\/b><\/span><\/span><\/span>).<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

A condu\u00e7\u00e3o t\u00e9rmica \u00e9 evitada pelo v\u00e1cuo entre as paredes duplas e pela tampa de material isolante. A <\/b><\/span><\/span>irradia\u00e7\u00e3o \u00e9 evitada pelas paredes espelhadas que refletem as radia\u00e7\u00f5es tanto interna como<\/b><\/span><\/span><\/span> <\/b>externamente.<\/b><\/span><\/span><\/span> A convec\u00e7\u00e3o \u00e9 evitada pelo v\u00e1cuo entre as paredes duplas.<\/b><\/span><\/span><\/p>\n

II. Correta<\/b><\/span><\/span><\/span> \"\" <\/b><\/span><\/span>\u00c9 o fen\u00f4meno pelo qual a energia emitida <\/b><\/span><\/span><\/span>pelo Sol chega at\u00e9 a Terra atrav\u00e9s do v\u00e1cuo.<\/b><\/span><\/span><\/span> <\/b><\/p>\n

\"\"<\/p>\n

Realiza-se atrav\u00e9s de <\/b><\/span><\/span><\/span>ondas eletromagn\u00e9ticas<\/b><\/span><\/span><\/span> que s\u00e3o compostas por diversas ondas de freq\u00fc\u00eancias diferentes (raios c\u00f3smicos, raios X, raios ultravioleta, luz vis\u00edvel, raios infravermelhos, microondas, etc.), chamadas radia\u00e7\u00f5es t\u00e9rmicas. Qualquer corpo que possua temperatura superior ao zero absoluto (0K ou -273<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sup><\/span>C) emite energia radiante e as que se transformam mais facilmente em calor quando absorvidas pelo receptor s\u00e3o as <\/b><\/span><\/span><\/span>infravermelhas, denominadas tamb\u00e9m de ondas de calor.<\/b><\/span><\/span><\/span><\/p>\n

A radia\u00e7\u00e3o ocorre tamb\u00e9m no ar, como voc\u00ea pode observar na figura a onde a m\u00e3o est\u00e1 recebendo <\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

calor por irradia\u00e7\u00e3o.<\/b><\/span><\/span><\/span><\/p>\n

III. Falsa<\/b><\/span><\/span><\/span> \"\" <\/b><\/span><\/span>\u00a0O gelo \u00e9 um excelente <\/b><\/span><\/span><\/span>isolante t\u00e9rmico, evitando perda de calor por condu\u00e7\u00e3o.<\/b><\/span><\/span><\/span>. Os esquim\u00f3s o utilizam para fazerem suas moradias que se denominam <\/b><\/span><\/span><\/span>iglus.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\u00a0Normalmente a parte interna \u00e9 forrada com peles de foca, deixando o recinto bastante confort\u00e1vel. A ilumina\u00e7\u00e3o \u00e9 garantida por uma janela feita ou de um bloco de gelo transparente ou de pele de foca ou de baleia.<\/b><\/span><\/span><\/span><\/p>\n

O calor da fogueira derrete parte dos blocos, mas a \u00e1gua escorre e congela novamente, refor\u00e7ando a veda\u00e7\u00e3o das paredes de gelo.<\/b><\/span><\/span><\/span><\/p>\n

Na entrada do iglu, \u00e9 constru\u00eddo um pequeno t\u00fanel para impedir<\/b><\/span><\/span><\/span> que o vento chegue ao interior<\/b><\/span><\/span><\/span><\/p>\n

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

05- <\/span><\/span><\/span>Efeito fotoel\u00e9trico<\/b><\/span><\/span><\/span>\u00a0– \u00a0\u00a0Heinrich Rudolf Hertz, em 1887, detectou e gerou em laborat\u00f3rio, em uma s <\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

s\u00e9rie de experi\u00eancias que,\u00a0<\/b><\/span><\/span>quando a <\/b><\/span><\/span>luz<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>(onda eletromagn\u00e9tica<\/b><\/span><\/span><\/span>, <\/b><\/span><\/span>radia\u00e7\u00e3o eletromagn\u00e9tica<\/b><\/span><\/span><\/span>) de freq\u00fc\u00eancia suficientemente alta <\/b><\/span><\/span>incide sobre a superf\u00edcie de um metal que a absorve<\/b><\/span><\/span><\/span>, <\/b><\/span><\/span>ela pode retirar el\u00e9trons do mesmo<\/b><\/span><\/span><\/span>. <\/b><\/span><\/span><\/span>Esse fen\u00f4meno ficou conhecido como<\/b><\/span><\/span>\u00a0efeito fotoel\u00e9trico.<\/b><\/span><\/span><\/span><\/p>\n

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

<\/h2>\n

Voltar para exerc\u00edcios.<\/span><\/a><\/h2>\n","protected":false},"excerpt":{"rendered":"

RESOLU\u00c7\u00d5ES 01- Tempo que o som, com velocidade de Vs = 340 m\/s demorou para ir de Fred at\u00e9 Hulk, percorrendo d=340m Vs = d\/t\u2019 340 = 340\/t\u2019 t\u2019 = 1s. Nesse tempo t\u2019 = 1s o carro com velocidade Vc percorreu uma dist\u00e3ncia x tal que Vc = x\/t\u2019 Vc = x\/1 Vc = x (I). Quando ouviu o<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":722,"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-725","page","type-page","status-publish","hentry"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/725","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=725"}],"version-history":[{"count":1,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/725\/revisions"}],"predecessor-version":[{"id":726,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/725\/revisions\/726"}],"up":[{"embeddable":true,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/722"}],"wp:attachment":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/media?parent=725"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}