{"id":355,"date":"2015-01-06T19:38:57","date_gmt":"2015-01-06T19:38:57","guid":{"rendered":"http:\/\/fisicaevestibular.com.br\/novo\/?page_id=355"},"modified":"2024-09-02T16:41:41","modified_gmt":"2024-09-02T16:41:41","slug":"resolucao-comentada-da-cefet-mg-2015","status":"publish","type":"page","link":"https:\/\/fisicaevestibular.com.br\/novo\/universidades-2015\/exercicios-da-cefet-mg-2015\/resolucao-comentada-da-cefet-mg-2015\/","title":{"rendered":"Resolu\u00e7\u00e3o comentada da CEFET MG 2015"},"content":{"rendered":"

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

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

\"\"<\/p>\n

\"\"<\/p>\n

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

\"\"<\/p>\n

\"\"<\/p>\n

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

\"\"<\/p>\n

Observando as <\/b><\/span><\/span><\/span>figuras<\/b><\/span><\/span><\/span> abaixo voc\u00ea verificar\u00e1 que, tanto na <\/b><\/span><\/span><\/span>Terra <\/b><\/span><\/span><\/span>quanto na <\/b><\/span><\/span><\/span>Lua,<\/b><\/span><\/span><\/span> os corpos est\u00e3o em <\/b><\/span><\/span><\/span>repouso<\/b><\/span><\/span><\/span> (<\/b><\/span><\/span><\/span>equil\u00edbrio est\u00e1tico<\/b><\/span><\/span><\/span>) e a <\/b><\/span><\/span><\/span>for\u00e7a resultante sobre eles deve ser nula.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

04- <\/b><\/span><\/span><\/span>O <\/b><\/span><\/span><\/span>per\u00edodo\u00a0<\/b><\/span><\/span><\/span>T<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>de um <\/b><\/span><\/span><\/span>MHS<\/b><\/span><\/span><\/span> \u00e9 fornecido pela <\/b><\/span><\/span><\/span>express\u00e3o:<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

T <\/b><\/span><\/span><\/span>\u2013 <\/b><\/span><\/span><\/span>per\u00edodo<\/b><\/span><\/span><\/span> \u2013 <\/b><\/span><\/span><\/span>tempo <\/b><\/span><\/span><\/span>que a <\/b><\/span><\/span><\/span>massa <\/b><\/span><\/span><\/span>m <\/b><\/span><\/span><\/span>demora para efetuar um <\/b><\/span><\/span><\/span>\u201cvai e vem\u201d completo<\/b><\/span><\/span><\/span><\/p>\n

m<\/b><\/span><\/span><\/span> \u2013 <\/b><\/span><\/span><\/span>massa<\/b><\/span><\/span><\/span> que executa o <\/b><\/span><\/span><\/span>MHS<\/b><\/span><\/span><\/span><\/p>\n

k<\/b><\/span><\/span><\/span> \u2013 <\/b><\/span><\/span><\/span>constante el\u00e1stica <\/b><\/span><\/span><\/span>da mola\u00a0<\/b><\/span><\/span><\/span><\/p>\n

Observe<\/b><\/span><\/span><\/span> na <\/b><\/span><\/span><\/span>express\u00e3o acima <\/b><\/span><\/span><\/span>que o <\/b><\/span><\/span><\/span>per\u00edodo T<\/b><\/span><\/span><\/span> (e <\/b><\/span><\/span><\/span>consequentemente a frequ\u00eancia <\/b><\/span><\/span><\/span>f <\/b><\/span><\/span><\/span>que \u00e9 o inverso do per\u00edodo) da <\/b><\/span><\/span><\/span>massa oscilante <\/b><\/span><\/span><\/span>n\u00e3o depende <\/b><\/span><\/span><\/span>da <\/b><\/span><\/span><\/span>amplitude <\/b><\/span><\/span><\/span>e nem da <\/b><\/span><\/span><\/span>acelera\u00e7\u00e3o da gravidade local<\/b><\/span><\/span><\/span>, <\/b><\/span><\/span><\/span>independente <\/b><\/span><\/span><\/span>do fato da oscila\u00e7\u00e3o ser na <\/b><\/span><\/span><\/span>horizontal, vertical ou num plano inclinado<\/b><\/span><\/span><\/span>, desde que seja a <\/b><\/span><\/span><\/span>mesma mola e a mesma massa.<\/b><\/span><\/span><\/span><\/p>\n

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

05- <\/b><\/span><\/span><\/span>A <\/b><\/span><\/span><\/span>express\u00e3o<\/b><\/span><\/span><\/span> matem\u00e1tica da <\/b><\/span><\/span><\/span>dilata\u00e7\u00e3o linear \u00e9 <\/b><\/span><\/span><\/span>\u2206L = L<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sub><\/span>.\u03b1,\u2206T.<\/b><\/span><\/span><\/span><\/p>\n

Como, para as <\/b><\/span><\/span><\/span>duas barras, o comprimento inicial <\/b><\/span><\/span><\/span>(L<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sub><\/span>) <\/b><\/span><\/span><\/span>e a varia\u00e7\u00e3o de temperatura <\/b><\/span><\/span><\/span>(\u2206T) <\/b><\/span><\/span><\/span>\u00e9 a <\/b><\/span><\/span><\/span>mesma, <\/b><\/span><\/span><\/span>a <\/b><\/span><\/span><\/span>dilata\u00e7\u00e3o <\/b><\/span><\/span><\/span>\u2206L<\/b><\/span><\/span><\/span> <\/b>de cada uma \u00e9 <\/b><\/span><\/span><\/span>diretamente proporcional ao coeficiente de dilata\u00e7\u00e3o <\/b><\/span><\/span><\/span>\u03b1.<\/b><\/span><\/span><\/span><\/p>\n

Observe na figura <\/b><\/span><\/span><\/span>1(b) <\/b><\/span><\/span><\/span>que, ap\u00f3s a <\/b><\/span><\/span><\/span>eleva\u00e7\u00e3o de temperatura <\/b><\/span><\/span><\/span>\u2206T > 0<\/b><\/span><\/span><\/span>, a <\/b><\/span><\/span><\/span>barra 1<\/b><\/span><\/span><\/span> sofreu <\/b><\/span><\/span><\/span>maior<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

dilata\u00e7\u00e3o que a <\/b><\/span><\/span><\/span>barra 2 <\/b><\/span><\/span><\/span>e, portanto, ela tem <\/b><\/span><\/span><\/span>maior coeficiente de dilata\u00e7\u00e3o linear, ou seja, <\/b><\/span><\/span><\/span>\u03b1<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span> > \u03b1<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>.<\/b><\/span><\/span><\/span><\/p>\n

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

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

\"\"<\/p>\n

07- <\/b><\/span><\/span><\/span>Quanto <\/b><\/span><\/span><\/span>mais refringente \u00e9 o meio<\/b><\/span><\/span><\/span>, <\/b><\/span><\/span><\/span>maior <\/b><\/span><\/span><\/span>ser\u00e1 o valor de <\/b><\/span><\/span><\/span>n,<\/b><\/span><\/span><\/span> <\/b>menor<\/b><\/span><\/span><\/span> a velocidade da luz nesse meio <\/b><\/span><\/span><\/span>e <\/b><\/span><\/span><\/span>maior<\/b><\/span><\/span><\/span> ser\u00e1 o desvio sofrido, com o raio de <\/b><\/span><\/span><\/span>luz se aproximando da normal.<\/b><\/span><\/span><\/span><\/p>\n

Maior <\/b><\/span><\/span><\/span>\u00e2ngulo com a normal<\/b><\/span><\/span><\/span>, menor <\/b><\/span><\/span><\/span>\u00edndice de refra\u00e7\u00e3o<\/b><\/span><\/span><\/span> e <\/b><\/span><\/span><\/span>vice versa.<\/b><\/span><\/span><\/span><\/p>\n

I. <\/b><\/span><\/span><\/span>A velocidade da luz nos meios 1 e 2 \u00e9 a mesma.<\/b><\/span><\/span><\/span><\/p>\n

I. <\/b><\/span><\/span><\/span>Falsa <\/b><\/span><\/span><\/span>— <\/b><\/span><\/span><\/span>O <\/b><\/span><\/span><\/span><\/span>\u00edndice de refra\u00e7\u00e3o <\/b><\/span><\/span><\/span><\/span>de um meio <\/b><\/span><\/span><\/span><\/span>representa a <\/b><\/span><\/span><\/span><\/span>raz\u00e3o<\/b><\/span><\/span><\/span><\/span> <\/b>(compara\u00e7\u00e3o) entre a <\/b><\/span><\/span><\/span><\/span>velocidade da luz no v\u00e1cuo e \u00a0a velocidade da luz no meio<\/b><\/span><\/span><\/span><\/span>, ou seja:<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

Na express\u00e3o <\/b><\/span><\/span><\/span>n = C\/V<\/b><\/span><\/span><\/span>, como <\/b><\/span><\/span><\/span>C <\/b><\/span><\/span><\/span>\u00e9 constante <\/b><\/span><\/span><\/span>n <\/b><\/span><\/span><\/span>\u00e9 inversamente proporcional a <\/b><\/span><\/span><\/span>V,<\/b><\/span><\/span><\/span> ou seja, <\/b><\/span><\/span><\/span>quanto <\/b><\/span><\/span><\/span><\/span>maior<\/b><\/span><\/span><\/span><\/span> for o \u00edndice de refra\u00e7\u00e3o de um meio (B da figura acima), <\/b><\/span><\/span><\/span><\/span>menor ser\u00e1 a velocidade da luz nele <\/b><\/span><\/span><\/span><\/span>e <\/b><\/span><\/span><\/span><\/span>maior<\/b><\/span><\/span><\/span><\/span> ser\u00e1 o <\/b><\/span><\/span><\/span><\/span>desvio<\/b><\/span><\/span><\/span><\/span> sofrido, com o <\/b><\/span><\/span><\/span><\/span>raio aproximando-se da normal.<\/b><\/span><\/span><\/span><\/span> Maior <\/b><\/span><\/span><\/span>\u00e2ngulo com a normal<\/b><\/span><\/span><\/span>, menor <\/b><\/span><\/span><\/span>\u00edndice de refra\u00e7\u00e3o<\/b><\/span><\/span><\/span> e <\/b><\/span><\/span><\/span>vice versa.<\/b><\/span><\/span><\/span><\/p>\n

II. <\/b><\/span><\/span><\/span>O \u00edndice de refra\u00e7\u00e3o do meio 2 \u00e9 o menor dentre os tr\u00eas meios<\/b><\/span><\/span><\/span>.<\/b><\/span><\/span><\/span><\/p>\n

II.<\/b><\/span><\/span><\/span> Falsa <\/b><\/span><\/span><\/span>— sendo <\/b><\/span><\/span><\/span>\u03b8<\/b><\/span><\/span><\/span>3<\/b><\/span><\/span><\/sub><\/span> > \u03b8<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>, ent\u00e3o <\/b><\/span><\/span><\/span>n<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span> > n<\/b><\/span><\/span><\/span>3<\/b><\/span><\/span><\/sub><\/span> <\/b>e, pelo enunciado <\/b><\/span><\/span><\/span>n<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span> < n<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>, portanto <\/b><\/span><\/span><\/span>n<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span> > n<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span> > n<\/b><\/span><\/span><\/span>3<\/b><\/span><\/span><\/sub><\/span>.<\/b><\/span><\/span><\/span><\/p>\n

III. <\/b><\/span><\/span><\/span>A velocidade da luz no meio 1 \u00e9 a menor dentre os tr\u00eas meios<\/b><\/span><\/span><\/span><\/p>\n

III. <\/b><\/span><\/span><\/span>Correta<\/b><\/span><\/span><\/span> — <\/b><\/span><\/span><\/span>maior<\/b><\/span><\/span><\/span> <\/b>\u00edndice de refra\u00e7\u00e3o<\/b><\/span><\/span><\/span>, <\/b><\/span><\/span><\/span>menor<\/b><\/span><\/span><\/span> <\/b>velocidade<\/b><\/span><\/span><\/span> e o <\/b><\/span><\/span><\/span>maio<\/b><\/span><\/span><\/span>r \u00edndice de refra\u00e7\u00e3o \u00e9 o do <\/b><\/span><\/span><\/span>meio 1 <\/b><\/span><\/span><\/span>(veja II).<\/b><\/span><\/span><\/span><\/p>\n

IV. <\/b><\/span><\/span><\/span>O \u00edndice de refra\u00e7\u00e3o do meio 3 \u00e9 menor que o \u00edndice de refra\u00e7\u00e3o do meio 1.<\/b><\/span><\/span><\/span><\/p>\n

IV. <\/b><\/span><\/span><\/span>Correta <\/b><\/span><\/span><\/span>— <\/b><\/span><\/span><\/span>Veja (II).<\/b><\/span><\/span><\/span><\/p>\n

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

08- <\/b><\/span><\/span><\/span>Sendo a <\/b><\/span><\/span><\/span>imagem <\/b><\/span><\/span><\/span>virtual e maior <\/b><\/span><\/span><\/span>n\u00e3o pode ser um <\/b><\/span><\/span><\/span>espelho plano <\/b><\/span><\/span><\/span>(imagem virtual e do mesmo tamanho que o do objeto), <\/b><\/span><\/span><\/span>nem uma <\/b><\/span><\/span><\/span>lente divergente ou um espelho convexo <\/b><\/span><\/span><\/span>que formam sempre <\/b><\/span><\/span><\/span>imagem virtual e menor que objeto<\/b><\/span><\/span><\/span>.<\/b><\/span><\/span><\/span><\/p>\n

Assim, das alternativas sobra o <\/b><\/span><\/span><\/span>espelho c\u00f4ncavo e a lente convergente <\/b><\/span><\/span><\/span>e, veja nas figuras abaixo<\/b><\/span><\/span><\/span><\/p>\n

\"\"que a alternativa correta \u00e9 a <\/b><\/span><\/span><\/span>lente convergente (da direita), onde, objeto e imagem est\u00e3o do mesmo lado (esquerdo),<\/b><\/span><\/span><\/span><\/p>\n

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

09- <\/b><\/span><\/span><\/span>I. <\/b><\/span><\/span><\/span>O <\/b><\/span><\/span><\/span>funcionamento de um gerador <\/b><\/span><\/span><\/span>de <\/b><\/span><\/span><\/span>corrente el\u00e9trica <\/b><\/span><\/span><\/span>pode ser explicado pela <\/b><\/span><\/span><\/span>lei de Faraday.<\/b><\/span><\/span><\/span><\/p>\n

I. <\/b><\/span><\/span><\/span>Verdadeira <\/b><\/span><\/span><\/span>— Geradores el\u00e9tricos <\/b><\/span><\/span><\/span>s\u00e3o dispositivos que <\/b><\/span><\/span><\/span>transformam <\/b><\/span><\/span><\/span>qualquer tipo de energia em energia<\/b><\/span><\/span><\/span> <\/b>el\u00e9trica<\/b><\/span><\/span><\/span>.<\/b><\/span><\/span><\/span><\/p>\n

O <\/b><\/span><\/span><\/span>mais comum<\/b><\/span><\/span><\/span>, o <\/b><\/span><\/span><\/span>d\u00ednamo <\/b><\/span><\/span><\/span>funciona <\/b><\/span><\/span><\/span>convertendo a energia mec\u00e2nica <\/b><\/span><\/span><\/span>contida na <\/b><\/span><\/span><\/span>rota\u00e7\u00e3o do eixo do <\/b><\/span><\/span><\/span>mesmo que faz com que a i<\/b><\/span><\/span><\/span>ntensidade <\/b><\/span><\/span><\/span>de um <\/b><\/span><\/span><\/span>campo magn\u00e9tico produzido por um\u00a0im\u00e3\u00a0<\/b><\/span><\/span><\/span>permanente que atravessa um conjunto de enrolamentos <\/b><\/span><\/span><\/span>varie no tempo<\/b><\/span><\/span><\/span>, o que pela <\/b><\/span><\/span><\/span>Lei da indu\u00e7\u00e3o de Faraday <\/b><\/span><\/span><\/span>leva a <\/b><\/span><\/span><\/span>indu\u00e7\u00e3o de tens\u00f5es<\/b><\/span><\/span><\/span>nos terminais dos mesmos.<\/b><\/span><\/span><\/span><\/p>\n

II. <\/b><\/span><\/span><\/span>Ao <\/b><\/span><\/span><\/span>girar o eixo de um motor <\/b><\/span><\/span><\/span>de <\/b><\/span><\/span><\/span>corrente cont\u00ednua<\/b><\/span><\/span><\/span>, com as m\u00e3os, ele <\/b><\/span><\/span><\/span>funcionar\u00e1 como um gerador de corrente el\u00e9trica.<\/b><\/span><\/span><\/span><\/p>\n

II. <\/b><\/span><\/span><\/span>Verdadeira <\/b><\/span><\/span><\/span>— <\/b><\/span><\/span><\/span><\/b>Veja I, <\/b><\/span><\/span><\/span>voc\u00ea estar\u00e1 <\/b><\/span><\/span><\/span>transformando energia mec\u00e2nica em energia el\u00e9trica<\/b><\/span><\/span><\/span>.<\/b><\/span><\/span><\/span><\/p>\n

III.<\/b><\/span><\/span><\/span> Um <\/b><\/span><\/span><\/span>fio<\/b><\/span><\/span><\/span> percorrido por uma <\/b><\/span><\/span><\/span>corrente el\u00e9trica <\/b><\/span><\/span><\/span>e colocado em um <\/b><\/span><\/span><\/span>campo magn\u00e9tico uniforme <\/b><\/span><\/span><\/span>sofrer\u00e1 a a\u00e7\u00e3o de uma <\/b><\/span><\/span><\/span>for\u00e7a magn\u00e9tica<\/b><\/span><\/span><\/span>, <\/b><\/span><\/span><\/span>independente da sua orienta\u00e7\u00e3o no campo.<\/b><\/span><\/span><\/span><\/p>\n

III. <\/b><\/span><\/span><\/span>Falsa <\/b><\/span><\/span><\/span>— express\u00e3o matem\u00e1tica da for\u00e7a magn\u00e9tica que age sobre o fio:<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

F<\/b><\/span><\/span><\/span>m<\/b><\/span><\/span><\/sub><\/span>\u00a0<\/b><\/span><\/span><\/span>\u2013 intensidade da <\/b><\/span><\/span><\/span>for\u00e7a magn\u00e9tica que age sobre o fio <\/b><\/span><\/span><\/span>\u2013 medida em newton (N), no SI.<\/b><\/span><\/span><\/span><\/p>\n

B<\/b><\/span><\/span><\/span> \u2013 intensidade do <\/b><\/span><\/span><\/span>campo magn\u00e9tico <\/b><\/span><\/span><\/span>\u2013 medido em tesla (T), no SI.<\/b><\/span><\/span><\/span><\/p>\n

i <\/b><\/span><\/span><\/span>\u2013 <\/b><\/span><\/span><\/span>corrente el\u00e9trica <\/b><\/span><\/span><\/span>no fio \u2013 medida em amp\u00e8re (A), no SI.<\/b><\/span><\/span><\/span><\/p>\n

\u03b8<\/b><\/span><\/span><\/span> \u2013 <\/b><\/span><\/span><\/span>\u00e2ngulo entre a dire\u00e7\u00e3o de <\/b><\/span><\/span><\/span>B e de i.<\/b><\/span><\/span><\/span><\/p>\n

Observe <\/b><\/span><\/span><\/span>nessa express\u00e3o <\/b><\/span><\/span><\/span>que, sendo <\/b><\/span><\/span><\/span>\u03b8<\/b><\/span><\/span><\/span> o \u00e2ngulo entre B e i<\/b><\/span><\/span><\/span>, o <\/b><\/span><\/span><\/span>seno de \u03b8 ser\u00e1 zero <\/b><\/span><\/span><\/span>quando <\/b><\/span><\/span><\/span>\u03b8=0<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sup><\/span> <\/b>ou <\/b><\/span><\/span><\/span>\u03b8=180<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sup><\/span>, ou seja, quando o <\/b><\/span><\/span><\/span>fio <\/b><\/span><\/span><\/span>percorrido pela corrente el\u00e9trica i estiver <\/b><\/span><\/span><\/span>disposto paralelamente ao<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

campo magn\u00e9tico B.<\/b><\/span><\/span><\/span><\/p>\n

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

10- <\/b><\/span><\/span><\/span>I. <\/b><\/span><\/span><\/span>A <\/b><\/span><\/span><\/span>chave <\/b><\/span><\/span><\/span>C <\/b><\/i><\/span><\/span><\/span>na posi\u00e7\u00e3o <\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/span> <\/b>corresponde a <\/b><\/span><\/span><\/span>\u00e1gua quente.<\/b><\/span><\/span><\/span><\/p>\n

I. <\/b><\/span><\/span><\/span>Verdadeira <\/b><\/span><\/span><\/span>—<\/b><\/span><\/span><\/span> <\/b>Com a chave na <\/b><\/span><\/span><\/span>posi\u00e7\u00e3o <\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/span>, o <\/b><\/span><\/span><\/span>resistor inferior de <\/b><\/span><\/span><\/span>8,0 \u2126 fica em curto-circuito <\/b><\/span><\/span><\/span>e \u00e9<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

eliminado<\/b><\/span><\/span><\/span>, com a <\/b><\/span><\/span><\/span>resist\u00eancia equivalente diminuindo <\/b><\/span><\/span><\/span>(passando de 16 \u2126 para 8 \u2126).<\/b><\/span><\/span><\/span><\/p>\n

Na <\/b><\/span><\/span><\/span>express\u00e3o <\/b><\/span><\/span><\/span>P = U<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sup><\/span>\/R<\/b><\/span><\/span><\/span>, <\/b><\/span><\/span><\/span>sendo a <\/b><\/span><\/span><\/span>ddp <\/b><\/span><\/span><\/span>U <\/b><\/span><\/span><\/span>a <\/b><\/span><\/span><\/span>mesma<\/b><\/span><\/span><\/span> com a chave <\/b><\/span><\/span><\/span>C em 1 ou em 2 <\/b><\/span><\/span><\/span>(220V)<\/b><\/span><\/span><\/span>, a resist\u00eancia <\/b><\/span><\/span><\/span>R<\/b><\/span><\/span><\/span> \u00e9 <\/b><\/span><\/span><\/span>inversamente proporcional \u00e0 pot\u00eancia el\u00e9trica <\/b><\/span><\/span><\/span>P<\/b><\/span><\/span><\/span> <\/b>e, assim, como <\/b><\/span><\/span><\/span>R diminui a P dever\u00e1 aumentar, aquecendo mais.<\/b><\/span><\/span><\/span><\/p>\n

II. <\/b><\/span><\/span><\/span>A <\/b><\/span><\/span><\/span>chave <\/b><\/span><\/span><\/span>C<\/b><\/i><\/span><\/span><\/span> <\/b><\/i>na posi\u00e7\u00e3o <\/b><\/span><\/span><\/span>“morno” <\/b><\/span><\/span><\/span>corresponde a uma <\/b><\/span><\/span><\/span>corrente de 13,75 A.<\/b><\/span><\/span><\/span><\/p>\n

II. <\/b><\/span><\/span><\/span>Verdadeira <\/b><\/span><\/span><\/span>— se, com a chave na posi\u00e7\u00e3o 1 estar\u00e1 em \u201cquente\u201d, na <\/b><\/span><\/span><\/span>posi\u00e7\u00e3o <\/b><\/span><\/span><\/span>2 <\/b><\/span><\/span><\/span>estar\u00e1 em <\/b><\/span><\/span><\/span>\u201cmorno\u201d <\/b><\/span><\/span><\/span>e, nela, passar\u00e1 corrente pelos dois resistores:<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

III. <\/b><\/span><\/span><\/span>A <\/b><\/span><\/span><\/span>chave <\/b><\/span><\/span><\/span>C<\/b><\/i><\/span><\/span><\/span> <\/b><\/i>na posi\u00e7\u00e3o <\/b><\/span><\/span><\/span>2 <\/b><\/span><\/span><\/span>corresponde a um <\/b><\/span><\/span><\/span>consumo de aproximadamente <\/b><\/span><\/span><\/span>3000 W.<\/b><\/span><\/span><\/span><\/p>\n

III. <\/b><\/span><\/span><\/span>Verdadeira <\/b><\/span><\/span><\/span>— <\/b><\/span><\/span><\/span>U = 220V i = 13,75 A <\/b><\/span><\/span><\/span>P = i.U <\/b><\/span><\/span><\/span>= 13,75.220 <\/b><\/span><\/span><\/span>P = 3025W.<\/b><\/span><\/span><\/span><\/p>\n

IV. <\/b><\/span><\/span><\/span>A <\/b><\/span><\/span><\/span>chave <\/b><\/span><\/span><\/span>C <\/b><\/i><\/span><\/span><\/span>na posi\u00e7\u00e3o <\/b><\/span><\/span><\/span>“quente<\/b><\/span><\/span><\/span>” <\/b><\/span><\/span><\/span>corresponde a uma <\/b><\/span><\/span><\/span>diferen\u00e7a de potencial de 110 V em cada resistor.<\/b><\/span><\/span><\/span><\/p>\n

IV. <\/b><\/span><\/span><\/span>Falsa<\/b><\/span><\/span><\/span> — na <\/b><\/span><\/span><\/span>posi\u00e7\u00e3o <\/b><\/span><\/span><\/span>quente <\/b><\/span><\/span><\/span>o chuveiro possui <\/b><\/span><\/span><\/span>apenas <\/b><\/span><\/span><\/span>uma <\/b><\/span><\/span><\/span>resist\u00eancia el\u00e9trica de 8 \u2126 e est\u00e1<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

submetido \u00e0 uma <\/b><\/span><\/span><\/span>ddp de 220V.<\/b><\/span><\/span><\/span><\/p>\n

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

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

RESOLU\u00c7\u00d5ES 01- 02- 03- Observando as figuras abaixo voc\u00ea verificar\u00e1 que, tanto na Terra quanto na Lua, os corpos est\u00e3o em repouso (equil\u00edbrio est\u00e1tico) e a for\u00e7a resultante sobre eles deve ser nula. 04- O per\u00edodo\u00a0T\u00a0de um MHS \u00e9 fornecido pela express\u00e3o: T \u2013 per\u00edodo \u2013 tempo que a massa m demora para efetuar um \u201cvai e vem\u201d completo m<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":353,"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-355","page","type-page","status-publish","hentry"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/355","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=355"}],"version-history":[{"count":2,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/355\/revisions"}],"predecessor-version":[{"id":357,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/355\/revisions\/357"}],"up":[{"embeddable":true,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/353"}],"wp:attachment":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/media?parent=355"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}