{"id":385,"date":"2015-01-15T03:01:12","date_gmt":"2015-01-15T03:01:12","guid":{"rendered":"http:\/\/fisicaevestibular.com.br\/novo\/?page_id=385"},"modified":"2024-09-02T16:49:24","modified_gmt":"2024-09-02T16:49:24","slug":"resolucao-comentada-da-fuvest-sp-2015","status":"publish","type":"page","link":"https:\/\/fisicaevestibular.com.br\/novo\/universidades-2015\/exercicios-da-fuvest-sp-2015\/resolucao-comentada-da-fuvest-sp-2015\/","title":{"rendered":"Resolu\u00e7\u00e3o comentada da FUVEST SP 2015"},"content":{"rendered":"

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

01- <\/b><\/span><\/span><\/span>Observe que<\/b><\/span><\/span><\/span>, apesar do desenho, fora de escala, na pr\u00e1tica, os <\/b><\/span><\/span>di\u00e2metros do pino e do cilindro<\/b><\/span><\/span><\/span><\/p>\n

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s\u00e3o aproximadamente iguais (d=4 mm).<\/b><\/span><\/span><\/span><\/p>\n

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Al\u00e9m dessas duas for\u00e7as acima<\/b><\/span><\/span><\/span>, agem sobre o pino a <\/b><\/span><\/span>for\u00e7a F<\/b><\/span><\/span><\/span>g<\/b><\/span><\/span><\/sub><\/span> <\/b>aplicada pelos gases da panela sobre<\/b><\/span><\/span><\/span> <\/b>ele<\/b><\/span><\/span><\/span>, (vertical e para cima) e a <\/b><\/span><\/span>for\u00e7a normal N<\/b><\/span><\/span><\/span> aplicada pelo tubo cil\u00edndrico, no apoio, sobre o pino.<\/b><\/span><\/span><\/span><\/p>\n

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

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

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dois <\/b><\/span><\/span><\/span>resistores de <\/b><\/span><\/span>mesma resist\u00eancia<\/b><\/span><\/span><\/span> e, assim <\/b><\/span><\/span>cada um deles ficar\u00e1 sujeito \u00e0 <\/b><\/span><\/span><\/span>220\/2 = 110 V,<\/b><\/span><\/span><\/span> como pede o enunciado.<\/b><\/span><\/span><\/span><\/p>\n

Correta<\/b><\/span><\/span><\/span><\/p>\n

Circuito II:<\/b><\/span><\/span><\/span><\/p>\n

Observe na <\/b><\/span><\/span>figura abaixo<\/b><\/span><\/span><\/span> que no <\/b><\/span><\/span>ramo inferior <\/b><\/span><\/span><\/span>cada<\/b><\/span><\/span><\/span> l\u00e2mpada est\u00e1 sob <\/b><\/span><\/span><\/span>tens\u00e3o de 55 V<\/b><\/span><\/span><\/span> e n\u00e3o de 110 V<\/b><\/span><\/span><\/span> como \u00e9 pedido.<\/b><\/span><\/span><\/p>\n

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No <\/b><\/span><\/span>ramo superior<\/b><\/span><\/span><\/span> as l\u00e2mpadas possuem <\/b><\/span><\/span>resist\u00eancias diferentes<\/b><\/span><\/span><\/span> e ent\u00e3o est\u00e3o sob <\/b><\/span><\/span>tens\u00f5es<\/b><\/span><\/span><\/span><\/p>\n

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diferentes.<\/b><\/span><\/span><\/span><\/p>\n

Errada<\/b><\/span><\/span><\/span><\/p>\n

Circuito III:<\/b><\/span><\/span><\/span><\/p>\n

Como, <\/b><\/span><\/span>cada ramo sob tens\u00e3o de 220 V<\/b><\/span><\/span><\/span>, possui <\/b><\/span><\/span>2 resistores iguais<\/b><\/span><\/span><\/span>, <\/b><\/span><\/span>cada um<\/b><\/span><\/span><\/span> desses resistores ficar\u00e1<\/b><\/span><\/span><\/p>\n

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sob <\/b><\/span><\/span>tens\u00e3o de 220V\/2 = 110V.<\/b><\/span><\/span><\/span><\/p>\n

Correta<\/b><\/span><\/span><\/span><\/p>\n

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

04- <\/span><\/span><\/span>Segunda lei da reflex\u00e3o da luz:<\/b><\/span><\/span><\/span><\/p>\n

\u201cO <\/b><\/span><\/span>\u00e2ngulo de incid\u00eancia <\/b><\/span><\/span><\/span>( i )<\/b><\/span><\/span><\/span> que o <\/b><\/span><\/span>raio incidente <\/b><\/span><\/span><\/span>forma com a normal (linha pontilhada)<\/b><\/span><\/span><\/span> \u00e9 <\/b><\/span><\/span>igual ao <\/b><\/span><\/span><\/span>\u00e2ngulo de reflex\u00e3o ( r )<\/b><\/span><\/span><\/span> que o raio refletido forma com a norma\u201d.<\/b><\/span><\/span><\/span><\/p>\n

\"\"\"\"\"\"<\/p>\n

Observe que essa lei \u00e9 <\/b><\/span><\/span>v\u00e1lida para espelhos planos, curvos e para qualquer tipo de superf\u00edcie refletora.<\/b><\/span><\/span><\/span><\/p>\n

Para espelhos esf\u00e9ricos,<\/b><\/span><\/span><\/span> como no exerc\u00edcio, <\/b><\/span><\/span>a <\/b><\/span><\/span><\/span>reta normal <\/b><\/span><\/span><\/span>\u00e9 a reta que <\/b><\/span><\/span><\/span>une o ponto de incid\u00eancia do raio de luz ao centro da circunfer\u00eancia que originou o espelho<\/b><\/span><\/span><\/span>(figura abaixo).<\/b><\/span><\/span><\/span><\/b><\/p>\n

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Veja na <\/b><\/span><\/span>figura acima<\/b><\/span><\/span><\/span> que <\/b><\/span><\/span>\u03b8<\/b><\/span><\/span><\/span>A<\/b><\/span><\/span><\/sub><\/span> > \u03b8<\/b><\/span><\/span><\/span>C<\/b><\/span><\/span><\/sub><\/span> > \u03b8<\/b><\/span><\/span><\/span>B<\/b><\/span><\/span><\/sub><\/span>.<\/b><\/span><\/span><\/span><\/p>\n

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

05- <\/span><\/span><\/span>Na <\/b><\/span><\/span>\u00f3rbita circular da figura<\/b><\/span><\/span><\/span> abaixo, <\/b><\/span><\/span>M<\/b><\/span><\/span><\/span> \u00e9 a massa da Terra<\/b><\/span><\/span><\/span>, <\/b><\/span><\/span>m <\/b><\/span><\/span><\/span>a massa do sat\u00e9lite<\/b><\/span><\/span><\/span>, <\/b><\/span><\/span>V<\/b><\/span><\/span><\/span> a velocidade de<\/b><\/span><\/span><\/span><\/b><\/p>\n

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06 – <\/b><\/span><\/span><\/span>Pelo enunciado<\/b><\/span><\/span><\/span>, como a esfera <\/b><\/span><\/span>desce<\/b><\/span><\/span><\/span> no interior da c\u00e2mara com <\/b><\/span><\/span>velocidade constante <\/b><\/span><\/span><\/span>ent\u00e3o ela est\u00e1 em <\/b><\/span><\/span>equil\u00edbrio din\u00e2mico<\/b><\/span><\/span><\/span> e a <\/b><\/span><\/span>for\u00e7a resultante<\/b><\/span><\/span><\/span> sobre ela deve ser <\/b><\/span><\/span><\/span>nula.<\/b><\/span><\/span><\/span><\/p>\n

Sendo a <\/b><\/span><\/span>for\u00e7a peso vertical e para baixo<\/b><\/span><\/span><\/span>, a <\/b><\/span><\/span>for\u00e7a el\u00e9trica<\/b><\/span><\/span><\/span> sobre a esfera, <\/b><\/span><\/span>para anular o peso<\/b><\/span><\/span><\/span>, deve ter <\/b><\/span><\/span>dire\u00e7\u00e3o vertical e sentido para cima.<\/b><\/span><\/span><\/span><\/p>\n

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Se, <\/b><\/span><\/span>pelo enunciado, o <\/b><\/span><\/span><\/span>campo el\u00e9trico<\/b><\/span><\/span><\/span> uniforme tem a mesma dire\u00e7\u00e3o e sentido da acelera\u00e7\u00e3o local da<\/b><\/span><\/span><\/span> <\/b>gravidade <\/b><\/span><\/span><\/span>(vertical e para baixo),<\/b><\/span><\/span><\/span> a <\/b><\/span><\/span>esfera<\/b><\/span><\/span><\/span> deve estar eletrizada com <\/b><\/span><\/span><\/span>carga negativa <\/b><\/span><\/span><\/span>(excesso de<\/b><\/span><\/span><\/span> <\/b>el\u00e9trons<\/b><\/span><\/span><\/span>)<\/b><\/span><\/span><\/span>, pois, para <\/b><\/span><\/span>cargas negativas a for\u00e7a el\u00e9trica e o campo el\u00e9trico<\/b><\/span><\/span><\/span> t\u00eam mesma dire\u00e7\u00e3o <\/b><\/span><\/span>(vertical)<\/b><\/span><\/span><\/span> e <\/b><\/span><\/span>sentido contr\u00e1rio<\/b><\/span><\/span><\/span> <\/b>(campo para baixo e for\u00e7a para cima).<\/b><\/span><\/span><\/span><\/b><\/p>\n

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07- <\/b><\/span><\/span><\/span>Vamos estabelecer como <\/b><\/span><\/span><\/span>positivo <\/b><\/span><\/span><\/span>o sentido das velocidades <\/b><\/span><\/span><\/span>para a direita.<\/b><\/span><\/span><\/span><\/p>\n

Na primeira situa\u00e7\u00e3o (antes de come\u00e7ar a andar) o trabalhador <\/b><\/span><\/span>de <\/b><\/span><\/span><\/span>massa m<\/b><\/span><\/span><\/span> est\u00e1 em p\u00e9, <\/b><\/span><\/span><\/span>em repouso<\/b><\/span><\/span><\/span>, sobre uma <\/b><\/span><\/span><\/span>plataforma de massa M<\/b><\/span><\/span><\/span>. O conjunto <\/b><\/span><\/span>se move, sem atrito, sobre trilhos horizontais e retil\u00edneos<\/b><\/span><\/span><\/span>, com <\/b><\/span><\/span>velocidade de m\u00f3dulo constante v, <\/b><\/span><\/span><\/span>ou seja, <\/b><\/span><\/span><\/span>trabalhador e plataforma possuem a mesma <\/b><\/span><\/span><\/span>velocidade V, <\/b><\/span><\/span><\/span>em rela\u00e7\u00e3o aos trilhos.<\/b><\/span><\/span><\/span><\/p>\n

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Depois, <\/b><\/span><\/span><\/span>o <\/b><\/span><\/span>trabalhador come\u00e7a a caminhar sobre a plataforma <\/b><\/span><\/span><\/span>e <\/b><\/span><\/span>permanece<\/b><\/span><\/span><\/span> com <\/b><\/span><\/span>velocidade de m\u00f3dulo v, em rela\u00e7\u00e3o a ela (cuidado \u00e9 em rela\u00e7\u00e3o \u00e0 plataforma)<\/b><\/span><\/span><\/span>, e com sentido <\/b><\/span><\/span>oposto ao do movimento dela em rela\u00e7\u00e3o aos trilhos, <\/b><\/span><\/span><\/span>ou seja, <\/b><\/span><\/span><\/span>trabalhador se move para a esquerda<\/b><\/span><\/span><\/span> com velocidade (- V)<\/b><\/span><\/span><\/span> e a <\/b><\/span><\/span><\/span>plataforma para a <\/b><\/span><\/span><\/span>direita com velocidade (V\u2019). <\/b><\/span><\/span><\/span>Observe que, <\/b><\/span><\/span>em rela\u00e7\u00e3o aos<\/b><\/span><\/span><\/span> <\/b>trilhos<\/b><\/span><\/span><\/span>, o trabalhado<\/b><\/span><\/span><\/span>r se move para a <\/b><\/span><\/span><\/span>direita <\/b><\/span><\/span><\/span>e sua velocidade ser\u00e1 <\/b><\/span><\/span><\/span>V<\/b><\/span><\/span><\/span>t<\/b><\/span><\/span><\/sub><\/span> = V\u2019 \u2013 V, pois V\u2019 > V (princ\u00edpio da <\/b><\/span><\/span><\/span>a\u00e7\u00e3o e rea\u00e7\u00e3o):<\/b><\/span><\/span><\/span><\/p>\n

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08- <\/b><\/span><\/span><\/span>I.<\/b><\/span><\/span><\/span> O <\/b><\/span><\/span>trabalho total<\/b><\/span><\/span><\/span> realizado no <\/b><\/span><\/span>ciclo ABCA \u00e9 nulo<\/b><\/span><\/span><\/span>.<\/b><\/span><\/span><\/p>\n

I.<\/b><\/span><\/span><\/span> <\/b>Falsa<\/b><\/span><\/span><\/span> — Em toda <\/b><\/span><\/span>transforma\u00e7\u00e3o c\u00edclica<\/b><\/span><\/span><\/span> representada no <\/b><\/span><\/span>diagrama PxV<\/b><\/span><\/span><\/span>, o <\/b><\/span><\/span>trabalho realizado<\/b><\/span><\/span><\/span> \u00e9<\/b><\/span><\/span><\/p>\n

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fornecido pela \u00e1rea do ciclo<\/b><\/span><\/span><\/span>.<\/b><\/span><\/span><\/p>\n

Se o <\/b><\/span><\/span>ciclo \u00e9 realizado no <\/b><\/span><\/span><\/span>sentido hor\u00e1rio<\/b><\/span><\/span><\/span>, o trabalho \u00e9 <\/b><\/span><\/span><\/span>positivo.<\/b><\/span><\/span><\/span><\/p>\n

Se o <\/b><\/span><\/span>ciclo \u00e9 realizado<\/b><\/span><\/span><\/span> no <\/b><\/span><\/span>sentido anti-hor\u00e1rio<\/b><\/span><\/span><\/span>, o trabalho \u00e9 <\/b><\/span><\/span>negativo.<\/b><\/span><\/span><\/span><\/p>\n

II.<\/b><\/span><\/span><\/span> A <\/b><\/span><\/span>energia interna <\/b><\/span><\/span><\/span>do g\u00e1s no <\/b><\/span><\/span>estado C \u00e9 maior que no estado A.<\/b><\/span><\/span><\/span><\/p>\n

II.<\/b><\/span><\/span><\/span> Correto <\/b><\/span><\/span><\/span>— <\/b><\/span><\/span><\/b>no <\/b><\/span><\/span><\/span>trecho <\/b><\/span><\/span><\/span>CA<\/b><\/span><\/span><\/span> a transforma\u00e7\u00e3o \u00e9 <\/b><\/span><\/span><\/span>isovolum\u00e9trica onde o volume V<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span> \u00e9 constante<\/b><\/span><\/span><\/span>.<\/b><\/span><\/span><\/span><\/p>\n

Observe nas figuras abaixo que quanto <\/b><\/span><\/span>maior a temperatura<\/b><\/span><\/span><\/span> maior \u00e9 o movimento vibrat\u00f3rio das<\/b><\/span><\/span><\/p>\n

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mol\u00e9culas do g\u00e1s e\u00a0consequentemente maior a energia cin\u00e9tica (E<\/b><\/span><\/span>c<\/b><\/span><\/span><\/sub>) de suas mol\u00e9culas, o que implica <\/b><\/span><\/span>num aumento da energia interna (U) do g\u00e1s.<\/b><\/span><\/span><\/span><\/b><\/p>\n

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III.<\/b><\/span><\/span><\/span> Durante a <\/b><\/span><\/span>transforma\u00e7\u00e3o \"\"<\/b><\/span><\/span><\/span>, o g\u00e1s <\/b><\/span><\/span>recebe <\/b><\/span><\/span><\/span>calor<\/b><\/span><\/span><\/span> e realiza <\/b><\/span><\/span><\/span>trabalho.<\/b><\/span><\/span><\/span><\/p>\n

Observe no gr\u00e1fico que no <\/b><\/span><\/span>trecho AB<\/b><\/span><\/span><\/span> o <\/b><\/span><\/span>volume<\/b><\/span><\/span><\/span> est\u00e1 <\/b><\/span><\/span>aumentando<\/b><\/span><\/span><\/span> (V<\/b><\/span><\/span>B<\/b><\/span><\/span><\/sub> > V<\/b><\/span><\/span>A<\/b><\/span><\/span><\/sub>) e o <\/b><\/span><\/span>trabalho realizado \u00e9<\/b><\/span><\/span><\/span> <\/b>positivo<\/b><\/span><\/span><\/span>, pois, numa <\/b><\/span><\/span>isob\u00e1rica W = P.(V<\/b><\/span><\/span><\/span>B<\/b><\/span><\/span><\/sub><\/span> \u2013 V<\/b><\/span><\/span><\/span>A<\/b><\/span><\/span><\/sub><\/span>)<\/b><\/span><\/span><\/span> e, sendo <\/b><\/span><\/span>P positiva e constante e (V<\/b><\/span><\/span><\/span>B <\/b><\/span><\/span><\/sub><\/span>\u2013 V<\/b><\/span><\/span><\/span>A<\/b><\/span><\/span><\/sub><\/span>) > 0<\/b><\/span><\/span><\/span>, o <\/b><\/span><\/span>trabalho ser\u00e1 W<\/b><\/span><\/span><\/span>AB<\/b><\/span><\/span><\/sub><\/span> > 0.<\/b><\/span><\/span><\/span><\/p>\n

A transforma\u00e7\u00e3o <\/b><\/span><\/span>BC \u00e9 isot\u00e9rmica<\/b><\/span><\/span><\/span> (mesma temperatura, <\/b><\/span><\/span>T<\/b><\/span><\/span><\/span>B<\/b><\/span><\/span><\/sub><\/span> = T<\/b><\/span><\/span><\/span>C<\/b><\/span><\/span><\/sub><\/span>) e, como vimos em <\/b><\/span><\/span>I, T<\/b><\/span><\/span><\/span>B<\/b><\/span><\/span><\/sub><\/span>=T<\/b><\/span><\/span><\/span>C<\/b><\/span><\/span><\/sub><\/span> > T<\/b><\/span><\/span><\/span>A<\/b><\/span><\/span><\/sub><\/span> o que implica que <\/b><\/span><\/span>U<\/b><\/span><\/span><\/span>B<\/b><\/span><\/span><\/sub><\/span> > U<\/b><\/span><\/span><\/span>A<\/b><\/span><\/span><\/sub><\/span>\u00a0fazendo com que a <\/b><\/span><\/span>varia\u00e7\u00e3o de energia interna <\/b><\/span><\/span><\/span>\u2206U = U<\/b><\/span><\/span><\/span>B\u00ad<\/b><\/span><\/span><\/sub><\/span> \u2013 U<\/b><\/span><\/span><\/span>A<\/b><\/span><\/span><\/sub><\/span> seja positiva (\u2206U<\/b><\/span><\/span><\/span>AB<\/b><\/span><\/span><\/sub><\/span> > 0.<\/b><\/span><\/span><\/span><\/p>\n

Pela <\/b><\/span><\/span>segunda lei da termodin\u00e2mica <\/b><\/span><\/span><\/span>\u2206U = Q \u2013 W<\/b><\/span><\/span><\/span> \"\" <\/b><\/span><\/span>Q<\/b><\/span><\/span><\/span>AB<\/b><\/span><\/span><\/sub><\/span> =\u2206U<\/b><\/span><\/span><\/span>AB<\/b><\/span><\/span><\/sub><\/span> + W<\/b><\/span><\/span><\/span>AB<\/b><\/span><\/span><\/sub><\/span> \"\" <\/b><\/span><\/span>como \u2206U<\/b><\/span><\/span><\/span>AB<\/b><\/span><\/span><\/sub><\/span> e W<\/b><\/span><\/span><\/span>AB<\/b><\/span><\/span><\/sub><\/span> s\u00e3o positivos, Q<\/b><\/span><\/span><\/span>AB<\/b><\/span><\/span><\/sub><\/span> > 0 e o g\u00e1s recebe calor e realiza trabalho. \u00a0<\/b><\/span><\/span><\/span><\/p>\n

R- E\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/b><\/span><\/span><\/span><\/p>\n

09- <\/b><\/span><\/span><\/span>For\u00e7as<\/b><\/span><\/span><\/span> que agem sobre o <\/b><\/span><\/span>sistema <\/b><\/span><\/span><\/span>(guindaste + carga):<\/b><\/span><\/span><\/span><\/p>\n

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Colocando o <\/b><\/span><\/span>p\u00f3lo (eixo de rota\u00e7\u00e3o) no ponto (0,0), rodas dianteiras<\/b><\/span><\/span><\/span>, e calculando o <\/b><\/span><\/span>momento de cada<\/b><\/span><\/span><\/span> <\/b>for\u00e7a em rela\u00e7\u00e3o ao p\u00f3lo<\/b><\/span><\/span><\/span>, e estabelecendo o <\/b><\/span><\/span>sentido hor\u00e1rio de rota\u00e7\u00e3o como positivo:<\/b><\/span><\/span><\/span><\/p>\n

M<\/b><\/span><\/span><\/span>Pg<\/b><\/span><\/span><\/sub><\/span> <\/b>= – P<\/b><\/span><\/span><\/span>g<\/b><\/span><\/span><\/sub><\/span>.d<\/b><\/span><\/span><\/span> = – 50.000.3 \"\" <\/b><\/span><\/span>M<\/b><\/span><\/span><\/span>Pg<\/b><\/span><\/span><\/sub><\/span> = – 150.000 N.m.<\/b><\/span><\/span><\/span><\/p>\n

M<\/b><\/span><\/span><\/span><\/span>N<\/b><\/span><\/span><\/span><\/sub><\/span> <\/b>= <\/b><\/span><\/span><\/span>N.d<\/b><\/span><\/span><\/span><\/span> = N.0 \"\" <\/b><\/span><\/span><\/span>M<\/b><\/span><\/span><\/span><\/span>N<\/b><\/span><\/span><\/span><\/sub><\/span> = 0.<\/b><\/span><\/span><\/span><\/span><\/p>\n

M<\/b><\/span><\/span><\/span><\/span>P<\/b><\/span><\/span><\/span><\/sub><\/span> <\/b>= <\/b><\/span><\/span><\/span>+ P.d<\/b><\/span><\/span><\/span><\/span> = + P.2 \"\" <\/b><\/span><\/span><\/span>M<\/b><\/span><\/span><\/span><\/span>P<\/b><\/span><\/span><\/span><\/sub><\/span> = 2P.<\/b><\/span><\/span><\/span><\/span><\/p>\n

No <\/b><\/span><\/span>equil\u00edbrio de rota\u00e7\u00e3o<\/b><\/span><\/span><\/span> a <\/b><\/span><\/span>soma dos momentos de cada for\u00e7a deve ser nulo:<\/b><\/span><\/span><\/span><\/p>\n

– 150.000 + 0 + 2P = 0<\/b><\/span><\/span><\/span> \"\" P = 150.000\/2 \"\" <\/b><\/span><\/span>P = 75.000 N.<\/b><\/span><\/span><\/span><\/p>\n

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

10- <\/b><\/span><\/span><\/span>O <\/b><\/span><\/span>enunciado afirma<\/b><\/span><\/span><\/span> que a esfera est\u00e1 em <\/b><\/span><\/span>repouso na posi\u00e7\u00e3o x = x<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span> <\/b>o que implica que, <\/b><\/span><\/span>nessa posi\u00e7\u00e3o, sua energia cin\u00e9tica \u00e9 nula<\/b><\/span><\/span><\/span> (E<\/b><\/span><\/span>c<\/b><\/span><\/span><\/sub> = mV<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sup>\/2 = m.0<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sup>\/2=0).<\/b><\/span><\/span><\/p>\n

Sendo os <\/b><\/span><\/span>efeitos dissipativos desprez\u00edveis <\/b><\/span><\/span><\/span>voc\u00ea pode aplicar o <\/b><\/span><\/span>Princ\u00edpio da Conserva\u00e7\u00e3o da energia Mec\u00e2nica em que, para <\/b><\/span><\/span><\/span>qualquer posi\u00e7\u00e3o da trajet\u00f3ria, a energia mec\u00e2nica (E<\/b><\/span><\/span><\/span>m<\/b><\/span><\/span><\/sub><\/span>) \u00e9 constante<\/b><\/span><\/span><\/span>,<\/b><\/span><\/span><\/span> ou seja, a <\/b><\/span><\/span>soma das energias cin\u00e9tica (E\u00adc) e potencial gravitacional (E<\/b><\/span><\/span><\/span>p<\/b><\/span><\/span><\/sub><\/span>) em cada ponto fornece sempre o mesmo valor.<\/b><\/span><\/span><\/span><\/p>\n

Assim, se <\/b><\/span><\/span>E<\/b><\/span><\/span><\/span>m<\/b><\/span><\/span><\/sub><\/span> = E<\/b><\/span><\/span><\/span>c<\/b><\/span><\/span><\/sub><\/span> + E<\/b><\/span><\/span><\/span>p<\/b><\/span><\/span><\/sub><\/span> = constante<\/b><\/span><\/span><\/span>, ent\u00e3o no ponto <\/b><\/span><\/span>x = x<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span> onde a cin\u00e9tica \u00e9 nula a <\/b><\/span><\/span><\/span>potencial ser\u00e1 m\u00e1xima.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Da mesma maneira, se <\/b><\/span><\/span>E<\/b><\/span><\/span><\/span>m<\/b><\/span><\/span><\/sub><\/span> = E<\/b><\/span><\/span><\/span>c<\/b><\/span><\/span><\/sub><\/span> + E<\/b><\/span><\/span><\/span>p<\/b><\/span><\/span><\/sub><\/span> = constante<\/b><\/span><\/span><\/span>, ent\u00e3o no ponto <\/b><\/span><\/span>x = x<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span> onde a energia potencial gravitacional \u00e9 m\u00ednima (veja gr\u00e1fico) e de valor U<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sub><\/span>, <\/b><\/span><\/span><\/span>a cin\u00e9tica ser\u00e1 m\u00e1xima.<\/b><\/span><\/span><\/span><\/p>\n

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

11- <\/b><\/span><\/span><\/span>Observe na figura abaixo<\/b><\/span><\/span><\/span> que entre a primeira <\/b><\/span><\/span>tecla (nota) D\u00f31 e a segunda D\u00f32 voc\u00ea tem 13 teclas (notas).<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

O <\/b><\/span><\/span>enunciado pede o comprimento de onda, no ar, da <\/b><\/span><\/span><\/span>nota Sol<\/b><\/span><\/span><\/span>, fornecendo que a <\/b><\/span><\/span>frequ\u00eancia<\/b><\/span><\/span><\/span> da nota <\/b><\/span><\/span>L\u00e1 <\/b><\/span><\/span><\/span>do teclado da figura <\/b><\/span><\/span>\u00e9 440 Hz.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

12- <\/b><\/span><\/span><\/span>A <\/b><\/span><\/span>termodin\u00e2mica<\/b><\/span><\/span><\/span> nasceu no s\u00e9culo XIX, como resultado das <\/b><\/span><\/span>preocupa\u00e7\u00f5es relativas \u00e0s m\u00e1quinas a<\/b><\/span><\/span><\/span> <\/b>vapor,<\/b><\/span><\/span><\/span> dos la\u00e7os entre os <\/b><\/span><\/span>fen\u00f4menos mec\u00e2nicos e os t\u00e9rmicos assim como da evolu\u00e7\u00e3o da calorimetria.<\/b><\/span><\/span><\/span><\/p>\n

Sem d\u00favida alguma, ela permitiu a <\/b><\/span><\/span><\/span>revolu\u00e7\u00e3o industrial <\/b><\/span><\/span><\/span>e, na atualidade, <\/b><\/span><\/span><\/span>as m\u00e1quinas t\u00e9rmicas se baseiam<\/b><\/span><\/span><\/span> em seus<\/b><\/span><\/span><\/span>\u00a0princ\u00edpios.<\/b><\/span><\/span><\/span><\/p>\n

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

 <\/p>\n

Voltar para os Exerc\u00edcios da FUVEST 2015<\/a><\/span><\/h3>\n","protected":false},"excerpt":{"rendered":"

RESOLU\u00c7\u00d5ES 01- Observe que, apesar do desenho, fora de escala, na pr\u00e1tica, os di\u00e2metros do pino e do cilindro s\u00e3o aproximadamente iguais (d=4 mm). Al\u00e9m dessas duas for\u00e7as acima, agem sobre o pino a for\u00e7a Fg aplicada pelos gases da panela sobre ele, (vertical e para cima) e a for\u00e7a normal N aplicada pelo tubo cil\u00edndrico, no apoio, sobre o<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":383,"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-385","page","type-page","status-publish","hentry"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/385","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=385"}],"version-history":[{"count":1,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/385\/revisions"}],"predecessor-version":[{"id":386,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/385\/revisions\/386"}],"up":[{"embeddable":true,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/383"}],"wp:attachment":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/media?parent=385"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}