{"id":2130,"date":"2016-04-13T03:25:37","date_gmt":"2016-04-13T03:25:37","guid":{"rendered":"http:\/\/fisicaevestibular.com.br\/novo\/?page_id=2130"},"modified":"2024-08-21T15:01:34","modified_gmt":"2024-08-21T15:01:34","slug":"2130-2","status":"publish","type":"page","link":"https:\/\/fisicaevestibular.com.br\/novo\/fisica-termica\/termodinamica\/segunda-lei-da-termodinamica\/2130-2\/","title":{"rendered":"Segunda Lei da Termodin\u00e2mica"},"content":{"rendered":"

Resolu\u00e7\u00e3o comentada dos exerc\u00edcios de vestibulares sobre a <\/b><\/span><\/span><\/span><\/p>\n

Segunda Lei da Termodin\u00e2mica<\/b><\/span><\/span><\/span><\/p>\n

\u00a0<\/span><\/p>\n

01-<\/b><\/span><\/span>\u00a0\u03b7=1 \u2013 36\/45\u00a0 —\u00a0 \u03b7= 1 –\u00a0 0,8\u00a0 —\u00a0\u00a0<\/b><\/span><\/span>\u03b7=0,2=20%<\/b><\/span><\/span><\/p>\n

02<\/b><\/span><\/span><\/span>–<\/b><\/span><\/span><\/span> <\/b>a) \u03b7 = 1 \u2013 T<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\/T= 1 \u2013 (0 + 273)\/(100 + 273)\u00a0 —\u00a0 \u03b7 = 1 \u2013 273\/373=(373 \u2013 273)\/373\u00a0 —\u00a0\u00a0<\/b><\/span><\/span>\u03b7 =0,268 ou \u03b7 = 26,8%<\/b><\/span><\/span><\/p>\n

b) \u03b7 = 1 \u2013 Q<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\/Q\u00a0 —\u00a0 0,268= 1 \u2013 Q<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\/1.000\u00a0 —\u00a0\u00a0<\/b><\/span><\/span>Q<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>=732cal<\/b><\/span><\/span><\/p>\n

03<\/b><\/span><\/span><\/span>–\u00a0<\/b><\/span><\/span>\u03b7 = 1 \u2013 T<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\/T\u00a0 —\u00a0 0,25= 1 \u2013 (27 + 273)\/T\u00a0 —\u00a0 0,75=300\/T\u00a0 —\u00a0 T=300\/0,75\u00a0 —<\/b><\/span><\/span>\u00a0T=400K=127<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sup>C<\/b><\/span><\/span><\/p>\n

04<\/b><\/span><\/span><\/span>–<\/b><\/span><\/span><\/span> <\/b>\u03b7 = 1- 275\/300\u00a0 —\u00a0 \u03b7 = 25\/300\u00a0 —\u00a0 \u03b7 = 0,08\u00a0 —\u00a0<\/b><\/span><\/span>\u00a0\u03b7 = 8%<\/b><\/span><\/span><\/p>\n

05-<\/b><\/span><\/span><\/span> <\/b>R- V V V V V\u00a0\u00a0<\/b><\/span><\/span>—\u00a0 veja teoria<\/b><\/span><\/span><\/p>\n

06-<\/b><\/span><\/span><\/span> <\/b>R- D<\/b><\/span><\/span>\u00a0 —\u00a0 veja teoria\u00a0<\/b><\/span><\/span><\/p>\n

07-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>\u03b7=1 \u2013(273 \u2013 73)\/(273 + 227)=1 \u2013 200\/500\u00a0 —\u00a0 \u03b7=1 \u2013 0,4=0,6\u00a0 —\u00a0\u00a0<\/b><\/span><\/span>R- E<\/b><\/span><\/span><\/p>\n

08-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>(01) Falsa\u00a0 —\u00a0 veja teoria<\/b><\/span><\/span><\/p>\n

(02) Correta\u00a0 —\u00a0 veja teoria<\/b><\/span><\/span><\/p>\n

(04) Falsa\u00a0 —\u00a0 veja teoria<\/b><\/span><\/span><\/p>\n

(08) Verdadeira\u00a0 —\u00a0 o rendimento da m\u00e1quina de Carnot \u00e9 fun\u00e7\u00e3o exclusiva das temperaturas absolutas das fontes fria e quente e n\u00e3o depende da subst\u00e2ncia que faz a m\u00e1quina t\u00e9rmica funcionar.<\/b><\/span><\/span><\/p>\n

(16) Verdadeira\u00a0 —\u00a0 veja teoria<\/b><\/span><\/span><\/p>\n

R- (02+08+16) = 26<\/b><\/span><\/span><\/p>\n

09-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>01. Falsa\u00a0 —\u00a0 o ciclo de Carnot indica um rendimento m\u00e1ximo, mas menor que 100%.<\/b><\/span><\/span><\/p>\n

02. Verdadeira\u00a0 —\u00a0 \u03b7= 1 \u2013 (273 + 7)\/(273 + 37)= 1 \u2013 0,9\u00a0 —\u00a0 \u03b7=90%\u00a0 —\u00a0 20%<\u03b7<\/b><\/span><\/span><\/p>\n

04. Verdadeira\u00a0 —\u00a0 a \u00e1gua apresenta densidade m\u00e1xima a 4<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sup>C.<\/b><\/span><\/span><\/p>\n

08. Verdadeira\u00a0 —\u00a0 veja teoria.<\/b><\/span><\/span><\/p>\n

16. Falsa\u00a0 —\u00a0 n\u00e3o viola o princ\u00edpio da conserva\u00e7\u00e3o da energia.<\/b><\/span><\/span><\/p>\n

R-\u00a0 (02 + 04 + 08)=14<\/b><\/span><\/span><\/p>\n

10-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>W=Q<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\u00a0\u2013 \u2502Q<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\u2502=3,0.10<\/b><\/span><\/span>4<\/b><\/span><\/span><\/sup>J\u00a0 —\u00a0 \u03b7 = W\/Q<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0 0,6=3,0.10<\/b><\/span><\/span>4<\/b><\/span><\/span><\/sup>\/Q<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0\u00a0<\/b><\/span><\/span>Q<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>=5,0.10<\/b><\/span><\/span>4<\/b><\/span><\/span><\/sup>J\u00a0<\/b><\/span><\/span>\u00a0—\u00a0 Q<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\u2013 \u2502Q<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\u2502=3,0.10<\/b><\/span><\/span>4<\/b><\/span><\/span><\/sup>J\u00a0 —\u00a0 5,0.10<\/b><\/span><\/span>4<\/b><\/span><\/span><\/sup>\u00a0\u2013 \u2502Q<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\u2502= 3,0.10<\/b><\/span><\/span>4<\/b><\/span><\/span><\/sup>\u00a0 — \u00a0<\/b><\/span><\/span>\u2502Q<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\u2502= 2,0.10<\/b><\/span><\/span>4<\/b><\/span><\/span><\/sup>J<\/b><\/span><\/span>\u00a0 —\u00a0 primeira lei da termodin\u00e2mica\u00a0 —\u00a0 \u0394Q=W\u00a0 —\u00a0 \u0394U=\u0394Q \u2013 W\u00a0 —\u00a0 \u0394U=3,0.10<\/b><\/span><\/span>4<\/b><\/span><\/span><\/sup>\u00a0\u2013 3,0.10<\/b><\/span><\/span>4<\/b><\/span><\/span><\/sup>\u00a0 —\u00a0\u00a0<\/b><\/span><\/span>\u0394U=0\u00a0\u00a0<\/b><\/span><\/span>—\u00a0<\/b><\/span><\/span>R- D<\/b><\/span><\/span><\/p>\n

11-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>W= Q<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\u00a0\u2013 Q<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0 800=4.000 \u2013 Q<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0 Q<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>=3.200J\u00a0 —\u00a0 \u03b7 = 1 \u2013 Q<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\/Q<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0 \u03b7 = 1 \u2013 3.200\/4.000\u00a0 —\u00a0 \u03b7 = 1,0 \u2013 0,8\u00a0 —\u00a0 \u03b7 = 0,2\u00a0 —\u00a0<\/b><\/span><\/span><\/p>\n

\u03b7 = 1 \u2013 T<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\/T<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0 0,2= 1 \u2013 300\/T<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0 T<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>=300\/0,8\u00a0 —\u00a0 T<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>= 375K\u00a0 —<\/b><\/span><\/span>\u00a0 R- A<\/b><\/span><\/span><\/p>\n

12-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>I. Correta\u00a0 —\u00a0 os espa\u00e7os vazios entre as prateleiras facilitam as correntes de convec\u00e7\u00e3o.<\/b><\/span><\/span><\/p>\n

II. Falsa\u00a0 —\u00a0 a massa de gelo corresponde a um isolante t\u00e9rmico evitando que o congelador retire calor do interior da geladeira.<\/b><\/span><\/span><\/p>\n

III. Correta\u00a0 —\u00a0 o calor retirado do interior da geladeira deve sair pela \u201cgrade\u201d.<\/b><\/span><\/span><\/p>\n

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

13-<\/b><\/span><\/span><\/span> <\/b>R- E<\/b><\/span><\/span>\u00a0 —\u00a0 veja teoria<\/b><\/span><\/span><\/p>\n

14-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>Com T<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>=500K e T<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>=250K, o rendimento m\u00e1ximo dessa m\u00e1quina valeria\u00a0 —\u00a0 \u03b7 = 1 \u2013 T<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\/T<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>=1 \u2013 250\/500\u00a0 —\u00a0 \u03b7 = 0,5\u00a0 —\u00a0 se o trabalho produzido por essa m\u00e1quina fosse W=0,75Q<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\u00a0e o calor rejeitado fosse Q<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>=0,25Q<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>, o rendimento dessa m\u00e1quina seria\u00a0 —\u00a0 \u03b7 = Q<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\u00a0\u2013 Q<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\/Q<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0 \u03b7 = W\/Q<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>=0,75Q<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\/Q<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0 \u03b7 =0,75\u00a0 —\u00a0 esse rendimento \u00e9 imposs\u00edvel, pois \u00e9 maior que o rendimento de uma m\u00e1quina de Carnot operando entre as mesmas fontes\u00a0 —<\/b><\/span><\/span>\u00a0R- A<\/b><\/span><\/span><\/p>\n

15-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>No tempo 2, ocorre a compress\u00e3o: com as v\u00e1lvulas fechadas, o \u00eambolo sobe, movido pelo virabrequim, comprimindo a mistura ar combust\u00edvel<\/b><\/span><\/span>\u00a0rapidamente\u00a0\u00a0<\/b><\/span><\/span>—\u00a0 observe que como a compress\u00e3o \u00e9 muito r\u00e1pida, n\u00e3o ocorre trocas de calor com o meio, portanto o processo \u00e9 adiab\u00e1tico\u00a0 —\u00a0\u00a0<\/b><\/span><\/span>R- B<\/b><\/span><\/span><\/p>\n

16-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>\u03b7 = 1 \u2013 X\/400\u00a0 —\u00a0 1= 1 \u2013 X\/400\u00a0 —\u00a0 0=T\/400\u00a0 —\u00a0 T=0K\u00a0 —\u00a0<\/b><\/span><\/span>\u00a0R- D\u00a0\u00a0<\/b><\/span><\/span>—\u00a0 Observa\u00e7\u00e3o\u00a0 —\u00a0\u00a0<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>para o rendimento ser de 100% a temperatura da fonte fria deveria ser a temperatura absoluta 0K (-273<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sup>C), o que, de acordo com a segunda lei da Termodin\u00e2mica n\u00e3o pode ocorrer\u00a0 —\u00a0 veja teoria de entropia.<\/b><\/span><\/span><\/p>\n

17-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>I. Falsa\u00a0 —\u00a0 temperatura \u00e9 um n\u00famero associado ao n\u00edvel de vibra\u00e7\u00e3o das mol\u00e9culas.<\/b><\/span><\/span><\/p>\n

II. Verdadeira\u00a0 —\u00a0 veja teoria<\/b><\/span><\/span><\/p>\n

III. Verdadeira\u00a0 —\u00a0 adiab\u00e1tica\u00a0 —\u00a0 Q=0\u00a0 —\u00a0 \u0394U=Q \u2013 W\u00a0 —\u00a0 \u0394U= 0 \u2013 W\u00a0 —\u00a0 \u0394U=-W\u00a0 —\u00a0 observe que numa expans\u00e3o\u00a0 —\u00a0 W>0 e, consequentemente \u0394U<0.<\/b><\/span><\/span><\/p>\n

IV. Falsa\u00a0 —\u00a0 voc\u00ea pode comprimi-lo isotermicamente que sua temperatura aumenta.<\/b><\/span><\/span><\/p>\n

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

18-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>a) Transforma\u00e7\u00e3o Isot\u00e9rmica: ocorre \u00e0 temperatura constante\u00a0 —\u00a0 Transforma\u00e7\u00e3o adiab\u00e1tica: ocorre sem quem haja trocas de calor<\/b><\/span><\/span><\/p>\n

b) \u03b7=1 \u2013 400\/800=1 \u2013 \u00bd\u00a0 —\u00a0\u00a0<\/b><\/span><\/span>\u03b7=0,5=50%<\/b><\/span><\/span><\/p>\n

c) Se o rendimento \u00e9 de 50%, de todo calor recebido essa porcentagem \u00e9 transformada em trabalho\u00a0 —\u00a0\u00a0<\/b><\/span><\/span>W=500J<\/b><\/span><\/span><\/p>\n

19-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>\u03b7=30\/100=0,3\u00a0 —\u00a0 \u03b7 = 1 \u2013 T<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\/T<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0 0,3= 1 \u2013 T<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\/T<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0 T<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>=T<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\/0,7\u00a0 —\u00a0 T\u2019=2T<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0 T\u2019=2T<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\/0,7\u00a0 —\u00a0 T\u2019=T<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\/0,35\u00a0 —\u00a0 \u03b7\u2019=1 \u2013 T<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\/T<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0 \u03b7\u2019= 1 \u2013 T<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\/(T<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\/0,35)\u00a0 —\u00a0 \u03b7\u2019=1 \u2013 0,35\u00a0 —\u00a0 \u03b7\u2019=0,65\u00a0 —\u00a0\u00a0<\/b><\/span><\/span>R- E<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span><\/sub>\u00a0<\/b><\/span><\/span><\/sub>\u00a0<\/b><\/span><\/span><\/p>\n

20-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>C\u00e1lculo do m\u00e1ximo rendimento dessa m\u00e1quina\u00a0 —\u00a0 \u03b7 = 1 \u2013 300\/500\u00a0 —\u00a0 \u03b7=1,0 \u2013 0,6\u00a0 —\u00a0 \u03b7 = 0,4=40%\u00a0 —\u00a0 nenhuma das m\u00e1quinas pode ter rendimento superior a 0,4\u00a0 — A\u00a0 — \u03b7 =10.000\/10.000\u00a0 —\u00a0 \u03b7=1 (n\u00e3o pode, superior a 0,4)\u00a0 —\u00a0 B\u00a0 —\u00a0 \u03b7=6.000\/12.000\u00a0 —\u00a0 \u03b7=0,5 (n\u00e3o pode, superior a 0,4)\u00a0 —\u00a0 C\u00a0 —\u00a0 \u03b7=3.000\/8.000\u00a0 —\u00a0 \u03b7=0,375\u00a0 —\u00a0 (pode, inferior a 0,4)\u00a0 —\u00a0\u00a0<\/b><\/span><\/span>R- C<\/b><\/span><\/span><\/p>\n

21-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>I. Verdadeira\u00a0 —\u00a0 veja teoria<\/b><\/span><\/span><\/p>\n

II. Falsa\u00a0 —\u00a0 como no decorrer do ciclo a temperatura varia, energia interna tamb\u00e9m variar\u00e1<\/b><\/span><\/span><\/p>\n

III. Falsa\u00a0 — \u00e9 imposs\u00edvel transformar todo calor recebido em trabalho<\/b><\/span><\/span><\/p>\n

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

22-<\/b><\/span><\/span><\/span> <\/b>R- C\u00a0<\/b><\/span><\/span>\u00a0—\u00a0 veja teoria<\/b><\/span><\/span><\/p>\n

23-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>01. Correta\u00a0 —\u00a0 compress\u00e3o r\u00e1pida \u00e9 adiab\u00e1tica (n\u00e3o troca calor com o ambiente)\u00a0 — \u00a0Q=0\u00a0 —\u00a0 \u0394U=Q \u2013 W\u00a0 —\u00a0 \u0394U= -W\u00a0 —\u00a0 na compress\u00e3o o volume diminui e o W \u00e9 negativo\u00a0 —\u00a0 \u0394U= – (-W)\u00a0 —\u00a0 \u0394U > 0.<\/b><\/span><\/span><\/p>\n

02. Falsa\u00a0 —\u00a0 duas isot\u00e9rmicas e duas adiab\u00e1ticas.<\/b><\/span><\/span><\/p>\n

04. Falsa\u00a0 —\u00a0 depende tamb\u00e9m da temperatura da fonte fria.<\/b><\/span><\/span><\/p>\n

08. Correta\u00a0 —\u00a0 veja teoria<\/b><\/span><\/span><\/p>\n

16. Correta\u00a0 —\u00a0 veja teoria<\/b><\/span><\/span><\/p>\n

R- (01 + 08 + 16)=25<\/b><\/span><\/span><\/p>\n

24-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>Temperatura est\u00e1 associada ao numero que mede o movimento oscilat\u00f3rio das mol\u00e9culas\u00a0 —\u00a0 no compartimento das mais velozes, a temperatura \u00e9 maior e no das mais lentas, a temperatura \u00e9 maior\u00a0 —\u00a0\u00a0<\/b><\/span><\/span>R- A<\/b><\/span><\/span><\/p>\n

25-<\/b><\/span><\/span><\/span> <\/b>R- E\u00a0<\/b><\/span><\/span>\u00a0—\u00a0 sempre que o g\u00e1s se expande, seu volume ao aumentar, produz trabalho positivo.<\/b><\/span><\/span><\/p>\n

26-<\/b><\/span><\/span><\/span> <\/b>R- A<\/b><\/span><\/span>\u00a0 —\u00a0 O Segundo Princ\u00edpio da Termodin\u00e2mica que um sistema isolado tende a evoluir no sentido de aumentar a entropia.<\/b><\/span><\/span><\/p>\n

27-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>Como a entropia refere-se \u00e0 desordem do sistema, a entropia diminui\u00a0 —\u00a0<\/b><\/span><\/span>\u00a0R- A<\/b><\/span><\/span><\/p>\n

28-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>a) Utilizando a equa\u00e7\u00e3o\u00a0 —\u00a0 E<\/b><\/span><\/span>a<\/b><\/span><\/span><\/sub>\u22481 \u2013 1\/\u221ar<\/b><\/span><\/span>a<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0 E<\/b><\/span><\/span>a<\/b><\/span><\/span><\/sub>=1 \u2013 1\/\u221a11=1 \u2013 1\/(10\/3)\u00a0 —\u00a0 E<\/b><\/span><\/span>a<\/b><\/span><\/span><\/sub>=1 \u2013 3\/10\u00a0 —\u00a0<\/b><\/span><\/span>\u00a0E<\/b><\/span><\/span>a<\/b><\/span><\/span><\/sub>=0,7=70%<\/b><\/span><\/span>\u00a0 —\u00a0 E<\/b><\/span><\/span>g<\/b><\/span><\/span><\/sub>\u22481 \u2013 1\/\u221ar<\/b><\/span><\/span>g<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0 E<\/b><\/span><\/span>g<\/b><\/span><\/span><\/sub>=1 \u2013 1\/\u221a9=1 \u2013 1\/3\u00a0 —\u00a0 E<\/b><\/span><\/span>g<\/b><\/span><\/span><\/sub>=2\/3\u00a0 —<\/b><\/span><\/span>\u00a0E<\/b><\/span><\/span>g<\/b><\/span><\/span><\/sub>=0,67=67%<\/b><\/span><\/span><\/p>\n

b) P<\/b><\/span><\/span><\/span>f<\/b><\/span><\/span><\/span><\/sub>V<\/b><\/span><\/span><\/span>f<\/b><\/span><\/span><\/span><\/sub>\/T<\/b><\/span><\/span><\/span>f<\/b><\/span><\/span><\/span><\/sub>= P<\/b><\/span><\/span><\/span>i<\/b><\/span><\/span><\/span><\/sub>V<\/b><\/span><\/span><\/span>i<\/b><\/span><\/span><\/span><\/sub>\/T<\/b><\/span><\/span><\/span>i<\/b><\/span><\/span><\/span><\/sub>\u00a0 — 30.36\/T<\/b><\/span><\/span><\/span>f<\/b><\/span><\/span><\/span><\/sub>=1.400\/300\u00a0 —\u00a0<\/b><\/span><\/span><\/span>\u00a0T<\/b><\/span><\/span><\/span>f<\/b><\/span><\/span><\/span><\/sub>=810K<\/b><\/span><\/span><\/span><\/p>\n

29-<\/b><\/span><\/span><\/span> <\/b>R- (01 + 04 + 16) = 21<\/b><\/span><\/span><\/p>\n

30-<\/b><\/span><\/span><\/span> <\/b>R- D\u00a0\u00a0<\/b><\/span><\/span>—\u00a0 veja teoria<\/b><\/span><\/span><\/p>\n

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

\"\"<\/p>\n

32-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>I. Falsa\u00a0 —\u00a0 A maior temperatura obtida por uma m\u00e1quina (motor) t\u00e9rmica \u00e9 a da combust\u00e3o, que \u00e9 a temperatura onde acontece a rea\u00e7\u00e3o qu\u00edmica do carboidrato com o oxig\u00eanio do ar, resultando em g\u00e1s carb\u00f4nico e \u00e1gua, sem rela\u00e7\u00e3o nenhuma com a temperatura de fervura.<\/b><\/span><\/span><\/p>\n

II. Correta\u00a0 —\u00a0 esta equa\u00e7\u00e3o \u00e9 a que fornece o rendimento de uma m\u00e1quina t\u00e9rmica ideal e pode ser utilizada para an\u00e1lise de rendimento de m\u00e1quinas reais.<\/b><\/span><\/span><\/p>\n

III. Correta\u00a0 —\u00a0 Carnot\u00a0 —\u00a0 \u201cO rendimento de uma m\u00e1quina t\u00e9rmica n\u00e3o depende do tipo de combust\u00edvel utilizado, dependendo apenas da temperatura da fonte quente (mais alta) e da fonte fria (mais baixa)\u201d<\/b><\/span><\/span><\/p>\n

IV. Correta\u00a0 —\u00a0 N\u00e3o existe m\u00e1quina t\u00e9rmica com rendimento de 100%, que consiga transformar integralmente calor em trabalho.<\/b><\/span><\/span><\/p>\n

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

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

\"\"<\/p>\n

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

34-<\/b><\/span><\/span><\/span>\u00a0\u00a0<\/b><\/span><\/span><\/span>I. Correta\u00a0 —\u00a0 O refrigerador \u00e9 uma m\u00e1quina t\u00e9rmica que transfere calor da fonte fria para a fonte quente.<\/b><\/span><\/span><\/p>\n

II. Correta\u00a0 —\u00a0 O refrigerador \u00e9 uma m\u00e1quina t\u00e9rmica que usa um l\u00edquido refrigerante com processos de condensa\u00e7\u00e3o e vaporiza\u00e7\u00e3o.<\/b><\/span><\/span><\/p>\n

III. Falsa\u00a0 —\u00a0 quanto maior o calor latente de vaporiza\u00e7\u00e3o do l\u00edquido refrigerante, menor \u00e9 o trabalho realizado pelo refrigerador.<\/b><\/span><\/span><\/p>\n

IV. Correta\u00a0 —\u00a0 O processo de refrigera\u00e7\u00e3o realiza trabalho por meio de um compressor que mant\u00e9m a circula\u00e7\u00e3o do fluido refrigerante, retirando calor da fonte fria e transferindo-o para a fonte quente.<\/b><\/span><\/span><\/p>\n

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

35<\/b><\/span><\/span><\/span>–\u00a0<\/b><\/span><\/span>Em um sistema de refrigera\u00e7\u00e3o, como uma geladeira ou ar-condicionado, o trabalho \u00e9 recebido para que o calor oriundo da fonte fria seja transferido para a fonte quente\u00a0 —\u00a0 R<\/b><\/span><\/span>– D<\/b><\/span><\/span><\/p>\n

36-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>(01) Correta.<\/b><\/span><\/span><\/p>\n

(02) Correta.<\/b><\/span><\/span><\/p>\n

(04) Errada. A 2\u00aa lei da termodin\u00e2mica afirma que \u00e9 IMPOSS\u00cdVEL transformar integralmente calor em trabalho.<\/b><\/span><\/span><\/p>\n

(08) Correta.<\/b><\/span><\/span><\/p>\n

(16) Correta. A varia\u00e7\u00e3o da energia interna depende somente da temperatura. Se o processo \u00e9 c\u00edclico, o sistema retorna sempre \u00e0 temperatura inicial.\u00a0<\/b><\/span><\/span><\/p>\n

R- (01 + 02 + 08 + 16) = 27<\/b><\/span><\/span><\/p>\n

37-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>No ciclo temos as seguintes transforma\u00e7\u00f5es:<\/b><\/span><\/span><\/p>\n

JK\u00a0 —\u00a0 \u00a0expans\u00e3o isot\u00e9rmica. Se a entropia aumenta, o sistema recebe calor e realiza trabalho;<\/b><\/span><\/span><\/p>\n

KL\u00a0 —\u00a0 \u00a0resfriamento adiab\u00e1tico. A temperatura diminui sem variar a entropia, logo n\u00e3o h\u00e1 troca de calor;<\/b><\/span><\/span><\/p>\n

LM\u00a0 —\u00a0 \u00a0compress\u00e3o isot\u00e9rmica. A entropia diminui, o sistema perde calor e recebe trabalho;<\/b><\/span><\/span><\/p>\n

MJ\u00a0 —\u00a0 \u00a0aquecimento adiab\u00e1tico. A temperatura aumenta sem variar a entropia\u00a0 —\u00a0 observe que se trata de um ciclo de Carnot, com rendimento\u00a0 —\u00a0 \u03b7=1 \u2013 T<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\/T<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\u00a0\u00a0\u00a0—\u00a0 Calculo do trabalho realizado no ciclo, lembrando que a varia\u00e7\u00e3o da entropia \u00e9\u00a0 —\u00a0 \u0394S=Q\/T, onde Q \u00e9 o calor trocado na transforma\u00e7\u00e3o\u00a0 —\u00a0 a transforma\u00e7\u00e3o JK \u00e9 isot\u00e9rmica, portanto a varia\u00e7\u00e3o da energia interna \u00e9 nula\u00a0 —\u00a0\u00a0 da 1\u00aa lei da termodin\u00e2mica (\"\")\u00a0 —\u00a0 0 = Q<\/b><\/span><\/span>JK<\/b><\/span><\/span><\/sub>\u00a0\u2013 W<\/b><\/span><\/span>JK<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0 \u00a0W<\/b><\/span><\/span>JK<\/b><\/span><\/span><\/sub>\u00a0= Q<\/b><\/span><\/span>JK<\/b><\/span><\/span><\/sub>. (equa\u00e7\u00e3o 1)\u00a0 — \u00a0DS<\/b><\/span><\/span>JK<\/b><\/span><\/span><\/sub>= Q<\/b><\/span><\/span>JK<\/b><\/span><\/span><\/sub>\/T<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0 Q<\/b><\/span><\/span>JK<\/b><\/span><\/span><\/sub>=(S<\/b><\/span><\/span>J<\/b><\/span><\/span><\/sub>\u00a0\u2013 S<\/b><\/span><\/span>K<\/b><\/span><\/span><\/sub>).T<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0 Q<\/b><\/span><\/span>JK<\/b><\/span><\/span><\/sub>\u00a0= (S<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\u00a0\u2013 S<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>)T<\/b><\/span><\/span>2\u00a0<\/b><\/span><\/span><\/sub>\u00a0\u00a0—\u00a0 substituindo nessa express\u00e3o a equa\u00e7\u00e3o (1)\u00a0 —\u00a0 W<\/b><\/span><\/span>JK<\/b><\/span><\/span><\/sub>\u00a0= (S<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\u00a0\u2013 S<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>)T<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0 seguindo esse mesmo racioc\u00ednio para a transforma\u00e7\u00e3o LM, que tamb\u00e9m \u00e9 isot\u00e9rmica, mas com compress\u00e3o\u00a0 —\u00a0 W<\/b><\/span><\/span>LM<\/b><\/span><\/span><\/sub>\u00a0= (S<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\u00a0\u2013 S<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>)T<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\u00a0\u00de\u00a0 W<\/b><\/span><\/span>LM<\/b><\/span><\/span><\/sub>\u00a0= \u2013(S<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\u00a0\u2013 S<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>)T<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0 nas transforma\u00e7\u00f5es KL e MJ o sistema n\u00e3o troca calor\u00a0 —\u00a0 novamente, pela 1\u00aa lei da termodin\u00e2mica\u00a0 —\u00a0 DU<\/b><\/span><\/span>KL<\/b><\/span><\/span><\/sub>\u00a0= \u2013<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span><\/sub>W<\/b><\/span><\/span>KL<\/b><\/span><\/span><\/sub>\u00a0 e\u00a0 DU<\/b><\/span><\/span>MJ<\/b><\/span><\/span><\/sub>\u00a0= \u2013W<\/b><\/span><\/span>MJ<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0 \u00a0como DU<\/b><\/span><\/span>MJ<\/b><\/span><\/span><\/sub>\u00a0= \u2013<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span><\/sub>DU<\/b><\/span><\/span>KL\u00a0<\/b><\/span><\/span><\/sub>\u00de<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span><\/sup>W<\/b><\/span><\/span>MJ<\/b><\/span><\/span><\/sub>\u00a0= \u2013<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span><\/sub>W<\/b><\/span><\/span>KL<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0 o trabalho no ciclo \u00e9 o somat\u00f3rio desses trabalhos\u00a0 —\u00a0 W<\/b><\/span><\/span>ciclo<\/b><\/span><\/span><\/sub>\u00a0= W<\/b><\/span><\/span>JK<\/b><\/span><\/span><\/sub>\u00a0+ W<\/b><\/span><\/span>KL<\/b><\/span><\/span><\/sub>\u00a0+ W<\/b><\/span><\/span>LM<\/b><\/span><\/span><\/sub>\u00a0+ W<\/b><\/span><\/span>MJ<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0 W<\/b><\/span><\/span>ciclo<\/b><\/span><\/span><\/sub>\u00a0= (S<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\u00a0\u2013 S<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>)T<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\u00a0+ W<\/b><\/span><\/span>KL<\/b><\/span><\/span><\/sub>\u00a0\u2013 (S<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\u00a0\u2013 S<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>)T<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\u00a0\u2013 W<\/b><\/span><\/span>KL<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0 W<\/b><\/span><\/span>ciclo<\/b><\/span><\/span><\/sub>\u00a0= (S<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\u00a0\u2013 S<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>)T<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\u00a0\u2013 (S<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\u00a0\u2013 S<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>)T<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0 W<\/b><\/span><\/span>ciclo<\/b><\/span><\/span><\/sub>\u00a0= (S<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\u00a0\u2013 S<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>) (T<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\u00a0\u2013 T<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>).\u00a0<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span><\/p>\n

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

38-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>A 2\u00aa Lei da Termodin\u00e2mica afirma que nenhuma m\u00e1quina t\u00e9rmica, operando em ciclos entre uma fonte quente, \u00e0 temperatura T<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>, e uma fonte fria, \u00e0 temperatura T<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>, consegue transformar integralmente calor em trabalho. Portanto o rendimento nunca pode chegar a 100%, sendo no m\u00e1ximo, igual ao da m\u00e1quina de Carnot\u00a0 —\u00a0 de fato, analisando o gr\u00e1fico, vemos que o rendimento seria igual a 100% quando a raz\u00e3o T<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\/T<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\u00a0\u00a0fosse nula, ou seja\u00a0 —\u00a0 T<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\/T<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>=0\u00a0 —\u00a0 T<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>=0\u00a0 —\u00a0 a fonte fria teria que estar a 0 K, o que \u00e9 um absurdo\u00a0 —\u00a0 portanto o rendimento r \u00e9 sempre menor que 100%.\u00a0<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span><\/p>\n

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

39-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>Dados:\u00a0<\/b><\/span><\/span>T<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\u00a0= 27 \u00b0C = 300 K;\u00a0<\/b><\/span><\/span>Q<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\u00a0<\/b><\/span><\/span>= 40 kJ;\u00a0<\/b><\/span><\/span>W<\/b><\/span><\/span>\u00a0= 10 kJ.<\/b><\/span><\/span><\/p>\n

O rendimento (<\/b><\/span><\/span>h<\/b><\/span><\/span>) desse motor \u00e9\u00a0 —\u00a0 \u03b7=W\/Q<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>=10\/40\u00a0 —\u00a0 \u03b7=0,25=25%\u00a0 —\u00a0 aplicando esse rendimento ao ciclo de Carnot\u00a0 —\u00a0<\/b><\/span><\/span><\/p>\n

h = 1 \u2013\u00a0\"\"\u00a0\u00a0—\u00a0 \u00a0\u00a0\"\"h\u00a0\u00a0 —\u00a0 \u00a0T<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\u00a0=\"\"\u00a0\u00a0 —\u00a0 \u00a0\u00a0T<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\u00a0=\u00a0\"\"K\u00a0 —\u00a0 \u00a0\u00a0T<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\u00a0= 400 \u2013 273\u00a0 —\u00a0 \u00a0T<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\u00a0= 127 \u00b0C.\u00a0\u00a0\u00a0<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span><\/p>\n

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

40-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>(01) Correta.<\/b><\/span><\/span><\/p>\n

(02) Correta.<\/b><\/span><\/span><\/p>\n

(04) Errada. A 2\u00aa lei da termodin\u00e2mica afirma que \u00e9 IMPOSS\u00cdVEL transformar integralmente calor em trabalho.<\/b><\/span><\/span><\/p>\n

(08) Correta.<\/b><\/span><\/span><\/p>\n

(16) Correta. A varia\u00e7\u00e3o da energia interna depende somente da temperatura. Se o processo \u00e9 c\u00edclico, o sistema retorna sempre \u00e0 temperatura inicial.<\/b><\/span><\/span><\/p>\n

R- (01 + 02 + 08 + 16) = 27<\/b><\/span><\/span><\/p>\n

41-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>A termodin\u00e2mica estabelece que nenhuma m\u00e1quina operando em ciclos fornece rendimento maior que a m\u00e1quina ideal de Carnot.Portanto, r < 50%\u00a0 —\u00a0<\/b><\/span><\/span>\u00a0R- D<\/b><\/span><\/span><\/p>\n

42-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>Se a expans\u00e3o \u00e9 isot\u00e9rmica a energia interna n\u00e3o varia. Sendo o sistema n\u00e3o termicamente isolado, todo calor recebido pelo g\u00e1s \u00e9 transformado em trabalho\u00a0 —\u00a0<\/b><\/span><\/span>\u00a0R- A<\/b><\/span><\/span><\/p>\n

43-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>Respostas das quest\u00f5es de f\u00edsica:<\/b><\/span><\/span><\/p>\n

01. Falsa\u00a0 — \u00a0O ciclo de Carnot \u00e9 um ciclo te\u00f3rico que d\u00e1 o m\u00e1ximo rendimento que uma m\u00e1quina t\u00e9rmica poderia fornecer\u00a0 —\u00a0 na pr\u00e1tica, nenhum motor opera segundo esse ciclo.<\/b><\/span><\/span><\/p>\n

04. Falsa\u00a0 —\u00a0 a rela\u00e7\u00e3o entre for\u00e7a (F) e velocidade (v) depende da pot\u00eancia (P), pois\u00a0 —\u00a0 P = F.V<\/b><\/span><\/span><\/p>\n

08. Falsa\u00a0 —\u00a0 o calor de combust\u00e3o \u00e9 fornecido pela queima do combust\u00edvel\u00a0 —\u00a0 a fa\u00edsca \u00e9 somente para iniciar a combust\u00e3o.<\/b><\/span><\/span><\/p>\n

16. Correta. \u00a0\u00a0<\/b><\/span><\/span><\/p>\n

R- (02 + 16 + 64) = 82<\/b><\/span><\/span><\/p>\n

44-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>01. Resposta de Biologia. O neodarwinismo \u00e9 a s\u00edntese entre a teoria darwinista (s\u00e9c. XIX) e os conhecimentos de gen\u00e9tica (s\u00e9c. XX).<\/b><\/span><\/span><\/p>\n

02. Resposta de F\u00edsica\u00a0 —\u00a0 Falsa\u00a0 —\u00a0 a equa\u00e7\u00e3o geral dos gases, afirma que, para uma amostra de g\u00e1s ideal confinada num recipiente, vale a rela\u00e7\u00e3o\u00a0 —\u00a0 PV=nRT\u00a0 —\u00a0 atrav\u00e9s dessa express\u00e3o voc\u00ea observa que a teoria geral dos gases ideais \u00e9 assim resumida: \u201co produto press\u00e3o (P) x volume (V) \u00e9 diretamente proporcional \u00e0 temperatura absoluta (T) do g\u00e1s.\u201d\u00a0 —\u00a0 existe uma \u00fanica exce\u00e7\u00e3o que ocorre numa transforma\u00e7\u00e3o isot\u00e9rmica onde a temperatura absoluta \u00e9 constante e P.V=K e, nesse caso a press\u00e3o e o volume s\u00e3o inversamente proporcionais\u00a0 —\u00a0 mas trata-se apenas de um caso particular.<\/b><\/span><\/span><\/p>\n

04. Resposta de F\u00edsica\u00a0 —\u00a0 Falsa\u00a0 —\u00a0 a falta de comunica\u00e7\u00e3o entre os componentes da comunidade cient\u00edfica \u00e9 apenas um dos entraves\u00a0 —\u00a0 existem outros fatores, como por exemplo, falta de investimentos nessas novas tecnologias, dificuldades t\u00e9cnicas na constru\u00e7\u00e3o de equipamentos para elabora\u00e7\u00e3o dos produtos em escala comercial\u00a0 —\u00a0 tecnologia exige tecnologia.<\/b><\/span><\/span><\/p>\n

08) Resposta de F\u00edsica\u00a0 —\u00a0 falsa\u00a0 —\u00a0 a segunda lei da termodin\u00e2mica afirma exatamente o contr\u00e1rio: \u00e9 imposs\u00edvel transformar integralmente calor em trabalho.<\/b><\/span><\/span><\/p>\n

16. Resposta de F\u00edsica\u00a0 —\u00a0 Correta\u00a0 —\u00a0 o transporte de informa\u00e7\u00f5es atrav\u00e9s de fibras \u00f3pticas \u00e9 feito por reflex\u00e3o total no interior da fibra\u00a0 —\u00a0 esse fen\u00f4meno s\u00f3 \u00e9 poss\u00edvel quando o sentido de propaga\u00e7\u00e3o da luz \u00e9 do meio mais refringente (n\u00facleo) para o meio menos refringente (revestimento), como indicado na figura abaixo.<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

32. Resposta de Biologia\u00a0 —\u00a0 a conserva\u00e7\u00e3o dos alimentos imp\u00f5e a elimina\u00e7\u00e3o ou redu\u00e7\u00e3o da a\u00e7\u00e3o de microrganismos decompositores ou patog\u00eanicos como bact\u00e9rias, fungos e algas\u00a0 —\u00a0 os trabalhos de Pasteur contribu\u00edram para o desenvolvimento de t\u00e9cnicas de conserva\u00e7\u00e3o dos alimentos.\u00a0<\/b><\/span><\/span><\/p>\n

R- (01 + 16 + 32) = 49.<\/b><\/span><\/span><\/p>\n

45-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>A segunda lei da termodin\u00e2mica envolve a transforma\u00e7\u00e3o de calor em trabalho\u00a0 —\u00a0 dos processos dados, o \u00fanico que n\u00e3o envolve realiza\u00e7\u00e3o de trabalho \u00e9 o movimento de um sat\u00e9lite em \u00f3rbita, pois se trata de um sistema conservativo, j\u00e1 que ocorre\u00a0no v\u00e1cuo, n\u00e3o havendo atrito com o ar e consequentemente n\u00e3o provocando calor\u00a0 —\u00a0 assim, n\u00e3o h\u00e1 transforma\u00e7\u00e3o de calor em trabalho ou vice-versa, n\u00e3o violando, portanto, a segunda lei da termodin\u00e2mica, qualquer que seja o sentido de giro do sat\u00e9lite.\u00a0<\/b><\/span><\/span>\"\"<\/p>\n

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

46- Observe as figuras e as explica\u00e7\u00f5es abaixo\u00a0 —\u00a0 o primeiro tempo refere-se \u00e0 admiss\u00e3o, a mistura entra e o g\u00e1s se expande<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

isob\u00e1ricamemte (trecho OA)\u00a0 —\u00a0 o segundo tempo refere-se \u00e0 compress\u00e3o (trecho AD)\u00a0 —\u00a0 o terceiro tempo refere-se \u00e0 combust\u00e3o, cujo in\u00edcio ocorre devido \u00e0 fa\u00edsca el\u00e9trica (trecho DC)\u00a0 —\u00a0 o quarto tempo refere-se \u00e0 exaust\u00e3o (escape) ao final da qual os gases s\u00e3o expelidos (trecho CB)\u00a0 —\u00a0 a fa\u00edsca ocorre no in\u00edcio do trecho DC, em C e a libera\u00e7\u00e3o dos gases no final do trecho CB, em B\u00a0 —\u00a0<\/b><\/span><\/span>\u00a0R- D<\/b><\/span><\/span><\/p>\n

\u00a0<\/span><\/p>\n

\u00a047-<\/b><\/span><\/span><\/span> <\/b>I- Falsa\u00a0 —\u00a0m\u00e1quinas t\u00e9rmicas\u00a0\u2013 qualquer dispositivo capaz de transformar a energia interna de um combust\u00edvel em energia mec\u00e2nica\u00a0 —\u00a0 tamb\u00e9m pode ser definida como o dispositivo capaz de transformar parte de calor em trabalho.<\/b><\/span><\/span><\/p>\n

II. Correta\u00a0 —\u00a0\u00a0<\/b><\/span><\/span>e<\/b><\/span><\/span>nunciado de Clausius\u00a0 —\u00a0 n\u00e3o \u00e9 poss\u00edvel um processo cujo \u00fanico resultado seja a transfer\u00eancia de calor de um corpo de menor temperatura a outro de maior temperatura\u00a0 —\u00a0 para que isso ocorra \u00e9 preciso realizar trabalho\u00a0 —\u00a0 \u00a0as m\u00e1quinas frigor\u00edficas n\u00e3o contrariam o enunciado da segunda lei da Termodin\u00e2mica, que a referida passagem n\u00e3o \u00e9 espont\u00e2nea, ocorrendo \u00e0 custa de um trabalho externo. No refrigerador das geladeiras comuns existe um l\u00edquido refrigerante (freon, tetrafluoretano, etc,), que, ao sofrer expans\u00e3o passa do estado l\u00edquido ao estado gasoso, que abaixa a temperatura na serpentina interna (congelador).<\/b><\/span><\/span><\/p>\n

III. Falsa\u00a0 —\u00a0 contraria o segundo princ\u00edpio da termodin\u00e2mica que pode ser definido como: \u201c\u00c9 imposs\u00edvel obter uma m\u00e1quina t\u00e9rmica que, operando em ciclos, seja capaz de transformar totalmente o calor por ela recebido em trabalho\u201d.<\/b><\/span><\/span><\/p>\n

IV- Correta\u00a0 —\u00a0\u00a0<\/b><\/span><\/span>Ciclo\u00a0<\/b><\/span><\/span>de Carnot\u00a0\u00e9 o ciclo executado pela\u00a0m\u00e1quina de Carnot, idealizada pelo engenheiro franc\u00eas\u00a0Carnot\u00a0e que tem funcionamento apenas te\u00f3rico\u00a0 —\u00a0 funcionando entre duas transforma\u00e7\u00f5es\u00a0isot\u00e9rmicas\u00a0e duas\u00a0adiab\u00e1ticas\u00a0alternadamente, permite menor perda de energia (Calor) para o meio externo (fonte fria)\u00a0 —\u00a0 o rendimento da M\u00e1quina de Carnot \u00e9 o m\u00e1ximo que uma\u00a0m\u00e1quina t\u00e9rmica\u00a0trabalhando entre dadas temperaturas da fonte quente e da fonte fria pode ter (mas o rendimento nunca chega a 100%).<\/b><\/span><\/span><\/p>\n

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

<\/a> 48-<\/b><\/span><\/span><\/span> Pode-se definir o Segundo Princ\u00edpio da Termodin\u00e2mica da seguinte maneira: \u201c\u00c9 imposs\u00edvel obter uma m\u00e1quina t\u00e9rmica que, operando em ciclos, seja capaz de transformar totalmente o calor por ela recebido em trabalho\u201d\u00a0 — sempre haver\u00e1 energia dissipada pelo motor\u00a0 —\u00a0\u00a0\u00a0R- C.<\/b><\/span><\/span><\/p>\n

 <\/p>\n

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

Resolu\u00e7\u00e3o comentada dos exerc\u00edcios de vestibulares sobre a Segunda Lei da Termodin\u00e2mica \u00a0 01-\u00a0\u03b7=1 \u2013 36\/45\u00a0 —\u00a0 \u03b7= 1 –\u00a0 0,8\u00a0 —\u00a0\u00a0\u03b7=0,2=20% 02– a) \u03b7 = 1 \u2013 T1\/T= 1 \u2013 (0 + 273)\/(100 + 273)\u00a0 —\u00a0 \u03b7 = 1 \u2013 273\/373=(373 \u2013 273)\/373\u00a0 —\u00a0\u00a0\u03b7 =0,268 ou \u03b7 = 26,8% b) \u03b7 = 1 \u2013 Q1\/Q\u00a0 —\u00a0 0,268= 1 \u2013<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":2126,"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-2130","page","type-page","status-publish","hentry"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/2130","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=2130"}],"version-history":[{"count":5,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/2130\/revisions"}],"predecessor-version":[{"id":10746,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/2130\/revisions\/10746"}],"up":[{"embeddable":true,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/2126"}],"wp:attachment":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/media?parent=2130"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}