{"id":3755,"date":"2018-02-15T01:52:31","date_gmt":"2018-02-15T01:52:31","guid":{"rendered":"http:\/\/fisicaevestibular.com.br\/novo\/?page_id=3755"},"modified":"2024-08-20T23:04:50","modified_gmt":"2024-08-20T23:04:50","slug":"resolucao-comentada-fisica-termica-calor-sensivel-especifico","status":"publish","type":"page","link":"https:\/\/fisicaevestibular.com.br\/novo\/enem\/fisica-termica-calor-sensivel-especifico-trocas-de-calor-sem-mudanca-de-estado\/resolucao-comentada-fisica-termica-calor-sensivel-especifico\/","title":{"rendered":"F\u00edsica T\u00e9rmica – Resolu\u00e7\u00e3o"},"content":{"rendered":"

Resolu\u00e7\u00e3o Comentada<\/b><\/span><\/span><\/span> \u00a0<\/b><\/span><\/span><\/span><\/p>\n

F\u00edsica T\u00e9rmica<\/b><\/span><\/span><\/span><\/p>\n

Calor Sens\u00edvel (Espec\u00edfico) \u2013 Trocas de calor sem mudan\u00e7a de estado<\/b><\/span><\/span><\/span><\/p>\n

01-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>Observe os dados do gr\u00e1fico\u00a0 — \u00a0<\/b><\/span><\/span><\/span>R- C<\/b><\/span><\/span><\/span><\/p>\n

02-<\/b><\/span><\/span><\/span> <\/b>R- A<\/b><\/span><\/span><\/span>\u00a0 <\/b><\/span><\/span><\/span>—\u00a0 veja informa\u00e7\u00f5es abaixo:<\/b><\/span><\/span><\/span><\/p>\n

Nas regi\u00f5es des\u00e9rticas a amplitude t\u00e9rmica (diferen\u00e7a entre a m\u00e1xima e m\u00ednima temperaturas) \u00e9 bastante elevada e nas regi\u00f5es litor\u00e2neas ela \u00e9 bem menor devido ao alto calor espec\u00edfico da \u00e1gua <\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

em rela\u00e7\u00e3o a outras subst\u00e2ncias, \u00e9 que ela pode absorver ou\u00a0ceder grandes quantidades de calor com pequena altera\u00e7\u00e3o de temperatura. \u00a0Isto ocorre devido \u00e0s pontes de hidrog\u00eanio que mant\u00eam as mol\u00e9culas unidas. A aus\u00eancia de \u00e1gua faz um ambiente possuir um baixo calor espec\u00edfico, e desta forma o ambiente se aquece facilmente e se arrefece facilmente.<\/b><\/span><\/span><\/span><\/p>\n

03-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>Substituindo m=1g e \u0394t=1<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sup><\/span>C na express\u00e3o Q=m.c.\u0394t\u00a0 —\u00a0 Q=1.c.1 \u00a0—\u00a0 Q=c\u00a0 —\u00a0 ou seja,\u00a0o calor espec\u00edfico de uma subst\u00e2ncia \u00e9 a quantidade de calor necess\u00e1ria para fazer a temperatura da massa\u00a0 de 1g dessa subst\u00e2ncia sofrer uma varia\u00e7\u00e3o de temperatura de<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

1\u00a0<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sup><\/span>C, ou mais precisamente\u00a0 — \u00a0caloria (cal): quantidade de calor necess\u00e1ria para elevar a temperatura de 1g de \u00e1gua de 14,5<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sup><\/span>C a 15,5<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sup><\/span>C, ou seja, de 1<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sup><\/span>C, ou para diminuir a temperatura de 1g de \u00e1gua de 15,5<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sup><\/span>C para 14,5<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sup><\/span>C, ou seja , de 1<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sup><\/span>C\u00a0 —\u00a0 1 quilocaloria = 1 kcal=1.000 cal.<\/b><\/span><\/span><\/span><\/p>\n

04-\u00a0<\/b><\/span><\/span><\/span>Observe que eles possuem a mesma massa (m) e recebem a mesma quantidade de calor (Q)\u00a0\u00a0 —\u00a0 Q=m.c.\u0394\u03b8\u00a0 —\u00a0 \u0394\u03b8=Q\/m.c\u00a0 —como Q e m s\u00e3o constantes, a varia\u00e7\u00e3o de temperatura (\u0394\u03b8) \u00e9 inversamente proporcional ao calor espec\u00edfico (c)\u00a0 —\u00a0 observe na tabela que, aquele que apresenta menor calor espec\u00edfico \u00e9 o merc\u00fario\u00a0 —\u00a0<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>R- E<\/b><\/span><\/span><\/span><\/p>\n

05-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>Capacidade t\u00e9rmica de X\u00a0 —\u00a0 C<\/b><\/span><\/span><\/span>X<\/b><\/span><\/span><\/sub><\/span>=Q\/\u0394\u03b8<\/b><\/span><\/span><\/span>X<\/b><\/span><\/span><\/sub><\/span>\u00a0 —\u00a0 Q=C<\/b><\/span><\/span><\/span>X<\/b><\/span><\/span><\/sub><\/span>.\u0394\u03b8<\/b><\/span><\/span><\/span>X<\/b><\/span><\/span><\/sub><\/span>\u00a0 —\u00a0 Q=30C<\/b><\/span><\/span><\/span>X<\/b><\/span><\/span><\/sub><\/span>\u00a0 —\u00a0 capacidade t\u00e9rmica de Y\u00a0 —\u00a0 C<\/b><\/span><\/span><\/span>Y<\/b><\/span><\/span><\/sub><\/span>=Q\/\u0394\u03b8<\/b><\/span><\/span><\/span>Y<\/b><\/span><\/span><\/sub><\/span>\u00a0 —\u00a0 Q=C<\/b><\/span><\/span><\/span>y<\/b><\/span><\/span><\/sub><\/span>.\u0394\u03b8<\/b><\/span><\/span><\/span>Y<\/b><\/span><\/span><\/sub><\/span>\u00a0 —\u00a0 Q=60C<\/b><\/span><\/span><\/span>Y<\/b><\/span><\/span><\/sub><\/span>\u00a0 —\u00a0 30C<\/b><\/span><\/span><\/span>X<\/b><\/span><\/span><\/sub><\/span>=60C<\/b><\/span><\/span><\/span>Y<\/b><\/span><\/span><\/sub><\/span>\u00a0\u00a0—\u00a0 C<\/b><\/span><\/span><\/span>X<\/b><\/span><\/span><\/sub><\/span>=2C<\/b><\/span><\/span><\/span>Y<\/b><\/span><\/span><\/sub><\/span>\u00a0 —\u00a0<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>R-B<\/b><\/span><\/span><\/span>\u00a0\u00a0<\/b><\/span><\/span><\/span>—\u00a0 <\/b><\/span><\/span><\/span>observe que, quanto maior \u00e9 a capacidade t\u00e9rmica C ( e consequentemente o calor espec\u00edfico c, pois C=m.c) de um corpo, menor ser\u00e1 sua varia\u00e7\u00e3o de temperatura.<\/b><\/span><\/span><\/span><\/p>\n

06-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>A quantidade de calor total recebida corresponde \u00e0 soma das quantidades de calor sens\u00edvel\u00a0necess\u00e1rias para aquecer a \u00e1gua e a chaleira de alum\u00ednio\u00a0 —\u00a0 Q<\/b><\/span><\/span><\/span>total<\/b><\/span><\/span><\/sub><\/span>=Q<\/b><\/span><\/span><\/span>\u00e1gua\u00a0<\/b><\/span><\/span><\/sub><\/span>+ Q<\/b><\/span><\/span><\/span>aluminio<\/b><\/span><\/span><\/sub><\/span>\u00a0\u00a0—\u00a0 Q<\/b><\/span><\/span><\/span>total<\/b><\/span><\/span><\/sub><\/span>\u00a0= m<\/b><\/span><\/span><\/span>\u00e1gua<\/b><\/span><\/span><\/sub><\/span>.c<\/b><\/span><\/span><\/span>\u00e1gua<\/b><\/span><\/span><\/sub><\/span>.\u2206\u03b8 + m<\/b><\/span><\/span><\/span>aluminio<\/b><\/span><\/span><\/sub><\/span>.c<\/b><\/span><\/span><\/span>aluminio<\/b><\/span><\/span><\/sub><\/span>. \u2206\u03b8\u00a0 —\u00a0 Q<\/b><\/span><\/span><\/span>total<\/b><\/span><\/span><\/sub><\/span>=2 000.1.75 + 500.0,2.75\u00a0 —\u00a0 Q<\/b><\/span><\/span><\/span>total<\/b><\/span><\/span><\/sub><\/span>=157 500cal=157,5kcal (I)\u00a0 —\u00a0 o enunciado afirma que apenas 65% do calor de combust\u00e3o (Q<\/b><\/span><\/span><\/span>combust\u00e3o<\/b><\/span><\/span><\/sub><\/span>) \u00e9 utilizado no aquecimento\u00a0 —\u00a0 Q<\/b><\/span><\/span><\/span>\u00fatil<\/b><\/span><\/span><\/sub><\/span>=0,65Q<\/b><\/span><\/span><\/span>combust\u00e3o<\/b><\/span><\/span><\/sub><\/span>\u00a0 —\u00a0 Q<\/b><\/span><\/span><\/span>combust\u00e3o<\/b><\/span><\/span><\/sub><\/span>=m<\/b><\/span><\/span><\/span>g\u00e1s<\/b><\/span><\/span><\/sub><\/span>.12 000\u00a0 —\u00a0 Q<\/b><\/span><\/span><\/span>\u00fatil<\/b><\/span><\/span><\/sub><\/span>=0,65.m<\/b><\/span><\/span><\/span>g\u00e1s<\/b><\/span><\/span><\/sub><\/span>.12 000 (II)\u00a0 —\u00a0 igualando (I) com (II).\u00a0<\/b><\/span><\/span><\/span><\/p>\n

0,65.m<\/b><\/span><\/span><\/span>g\u00e1s<\/b><\/span><\/span><\/sub><\/span>.12 000 = 157,5\u00a0 —\u00a0 m<\/b><\/span><\/span><\/span>g\u00e1s<\/b><\/span><\/span><\/sub><\/span>=0,020kg=20g (quantidade a ser usada no aquecimento) — o butij\u00e3o cont\u00e9m uma massa de 1% da massa total\u00a0 —\u00a0 massa do butij\u00e3o\u00a0 —\u00a0 m<\/b><\/span><\/span><\/span>butij\u00e3o<\/b><\/span><\/span><\/sub><\/span>=0,01.13=0,13kg=130g\u00a0 —\u00a0 existe g\u00e1s suficiente, sendo usados apenas 20g e ainda sobrar\u00e3o no butij\u00e3o 110g de g\u00e1s\u00a0 —\u00a0\u00a0<\/b><\/span><\/span><\/span>R- B<\/b><\/span><\/span><\/span><\/p>\n

07-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>Quantidade de calor absorvida pelo pur\u00ea\u00a0 —\u00a0 Q=m.c.\u0394\u03b8=1.000×1,8x(50 \u2013 20)\u00a0 —\u00a0 Q=54.000calx4,18\u00a0 —\u00a0 Q=225.720J\u00a0 —\u00a0 80% da pot\u00eancia de 1.200W \u00e9 transferida para o prato\u00a0 —\u00a0 P=Q\/\u0394t\u00a0 —\u00a0 0,8×1.200=225.720\/\u0394t\u00a0 —\u00a0 \u0394t=235,125s\/60=3,918 minutos\u00a0 —<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>R- C<\/b><\/span><\/span><\/span><\/p>\n

08-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>d<\/b><\/span><\/span><\/span>\u00e1gua<\/b><\/span><\/span><\/sub><\/span>=m<\/b><\/span><\/span><\/span>\u00e1gua<\/b><\/span><\/span><\/sub><\/span>\/V<\/b><\/span><\/span><\/span>\u00e1gua<\/b><\/span><\/span><\/sub><\/span>\u00a0 —\u00a0 1=m<\/b><\/span><\/span><\/span>\u00e1gua<\/b><\/span><\/span><\/sub><\/span>\/8×250\u00a0 —\u00a0 m<\/b><\/span><\/span><\/span>\u00e1gua<\/b><\/span><\/span><\/sub><\/span>=2.000g (massa de \u00e1gua ingerida)\u00a0 —\u00a0 quantidade de calor fornecida pelo organismo da menina para elevar a temperatura dessa massa de \u00e1gua de 6,5<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sup><\/span>C at\u00e9 36,5<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sup><\/span>C\u00a0 —\u00a0 Q=m.c.(t \u2013 to)=2.000.1.30\u00a0 —\u00a0 Q=60.000cal\u00a0 —\u00a0 Q=60kcal\u00a0 —\u00a0<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>R- B<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span><\/p>\n

09-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>Energia cin\u00e9tica dissipada\u00a0 —\u00a0 Ec=m.V<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sup><\/span>\/2=30.000.(20)<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sup><\/span>\/2\u00a0 —\u00a0 Ec=6,0.10<\/b><\/span><\/span><\/span>6<\/b><\/span><\/span><\/sup><\/span>J\u00a0 —\u00a0 dessa energia, cada freio absorve sob forma de calor\u00a0 — Q<\/b><\/span><\/span><\/span>freio<\/b><\/span><\/span><\/sub><\/span>=6.10<\/b><\/span><\/span><\/span>6<\/b><\/span><\/span><\/sup><\/span>\/6\u00a0 —\u00a0 Q<\/b><\/span><\/span><\/span>freio<\/b><\/span><\/span><\/sub><\/span>=10<\/b><\/span><\/span><\/span>6<\/b><\/span><\/span><\/sup><\/span>J\u00a0 —\u00a0 Q<\/b><\/span><\/span><\/span>freio<\/b><\/span><\/span><\/sub><\/span>=m<\/b><\/span><\/span><\/span>freio<\/b><\/span><\/span><\/sub><\/span>.c<\/b><\/span><\/span><\/span>freio<\/b><\/span><\/span><\/sub><\/span>.\u0394t<\/b><\/span><\/span><\/span>freio<\/b><\/span><\/span><\/sub><\/span>\u00a0 —\u00a0 10<\/b><\/span><\/span><\/span>6<\/b><\/span><\/span><\/sup><\/span>=8.1.500. \u0394t<\/b><\/span><\/span><\/span>freio<\/b><\/span><\/span><\/sub><\/span>\u00a0 —\u00a0\u00a0\u0394t<\/b><\/span><\/span><\/span>freio<\/b><\/span><\/span><\/sub><\/span>=83<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sup><\/span>C\u00a0 —\u00a0\u00a0<\/b><\/span><\/span><\/span>R- E<\/b><\/span><\/span><\/span><\/p>\n

10-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>Densidade volum\u00e9trica\u00a0 —\u00a0 d=m\/V\u00a0 —\u00a0 m=d.V\u00a0 —\u00a0 vaz\u00e3o volum\u00e9trica\u00a0 —\u00a0 Z=volume de \u00e1gua despejada\/tempo\u00a0 —\u00a0 Z=V\/\u2206t\u00a0 —\u00a0 V=Z.\u2206t\u00a0 —\u00a0 m=d.Z.\u2206t\u00a0 —\u00a0 no equil\u00edbrio t\u00e9rmico, a temperatura final \u00e9 a mesma t=30<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sup><\/span>C\u00a0 —\u00a0 Q<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>\u00a0+ Q<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>\u00a0= 0\u00a0 —\u00a0 m<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>.c.\u2206\u03b8<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>\u00a0+ m<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>.c.\u2206\u03b8<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>\u00a0= 0\u00a0 —\u00a0 d.Z.\u2206t<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>.c.\u2206\u03b8<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>\u00a0+ d.Z.\u2206t<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>.c.\u2206\u03b8<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>\u00a0= 0\u00a0 —\u00a0 observe que d, Z e c s\u00e3o constantes (mesma subst\u00e2ncia, \u00e1gua e mesma vaz\u00e3o das torneiras)\u00a0 —\u00a0 .\u2206t<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>.\u2206\u03b8<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>\u00a0+ \u2206t<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>.\u2206\u03b8<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>\u00a0= 0\u00a0 —\u00a0 10.(30 \u2013 20) + \u2206t<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>(30 \u2013 70) = 0\u00a0 —\u00a0 100 – 40\u2206t<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>\u00a0= 0\u00a0 —\u00a0 \u2206t<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>\u00a0= 2,5 min\u00a0 —\u00a0<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span><\/p>\n

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

11-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>L\u00edquido\u00a0 —\u00a0 Q<\/b><\/span><\/span><\/span>l<\/b><\/span><\/span><\/sub><\/span>=m<\/b><\/span><\/span><\/span>l<\/b><\/span><\/span><\/sub><\/span>.c<\/b><\/span><\/span><\/span>l<\/b><\/span><\/span><\/sub><\/span>.(t<\/b><\/span><\/span><\/span>e<\/b><\/span><\/span><\/sub><\/span>\u00a0\u2013 t<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sub><\/span>)\u00a0 —\u00a0 entre 0<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sup><\/span>C e 120<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sup><\/span>C\u00a0 —\u00a0 300.000= m<\/b><\/span><\/span><\/span>l<\/b><\/span><\/span><\/sub><\/span>.c<\/b><\/span><\/span><\/span>l<\/b><\/span><\/span><\/sub><\/span>.(120 \u2013 0)\u00a0 —\u00a0 m<\/b><\/span><\/span><\/span>l<\/b><\/span><\/span><\/sub><\/span>.c<\/b><\/span><\/span><\/span>l<\/b><\/span><\/span><\/sub><\/span>=2.500\u00a0 —\u00a0metal\u00a0 — Q<\/b><\/span><\/span><\/span>m<\/b><\/span><\/span><\/sub><\/span>=m<\/b><\/span><\/span><\/span>m<\/b><\/span><\/span><\/sub><\/span>.c<\/b><\/span><\/span><\/span>m<\/b><\/span><\/span><\/sub><\/span>.(t<\/b><\/span><\/span><\/span>e<\/b><\/span><\/span><\/sub><\/span>\u00a0\u2013 t<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sub><\/span>)\u00a0 —\u00a0 entre 0<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sup><\/span>C e 100<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sup><\/span>C\u00a0 —\u00a0 100.000= m<\/b><\/span><\/span><\/span>m<\/b><\/span><\/span><\/sub><\/span>.c<\/b><\/span><\/span><\/span>m<\/b><\/span><\/span><\/sub><\/span>.(100 \u2013 0)\u00a0 —\u00a0 m<\/b><\/span><\/span><\/span>m<\/b><\/span><\/span><\/sub><\/span>.c<\/b><\/span><\/span><\/span>m<\/b><\/span><\/span><\/sub><\/span>=1.000\u00a0 —\u00a0 misturando-os\u00a0 —\u00a0 m<\/b><\/span><\/span><\/span>l<\/b><\/span><\/span><\/sub><\/span>.c<\/b><\/span><\/span><\/span>l<\/b><\/span><\/span><\/sub><\/span>.(t<\/b><\/span><\/span><\/span>e<\/b><\/span><\/span><\/sub><\/span>\u00a0\u2013 t<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sub><\/span>) + m<\/b><\/span><\/span><\/span>m<\/b><\/span><\/span><\/sub><\/span>.c<\/b><\/span><\/span><\/span>m<\/b><\/span><\/span><\/sub><\/span>.(t<\/b><\/span><\/span><\/span>e<\/b><\/span><\/span><\/sub><\/span>\u00a0\u2013 t<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sub><\/span>) = 0\u00a0 —\u00a0 2.500.(t<\/b><\/span><\/span><\/span>e<\/b><\/span><\/span><\/sub><\/span>\u2013 10) + 1.000.(t<\/b><\/span><\/span><\/span>e<\/b><\/span><\/span><\/sub><\/span>\u00a0\u2013 115) = 0\u00a0 —\u00a0 3.500t<\/b><\/span><\/span><\/span>e<\/b><\/span><\/span><\/sub><\/span>\u00a0= 140.000\u00a0 —\u00a0 t<\/b><\/span><\/span><\/span>e<\/b><\/span><\/span><\/sub><\/span>=40<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sup><\/span>C\u00a0 —\u00a0\u00a0<\/b><\/span><\/span><\/span>R- E<\/b><\/span><\/span><\/span><\/p>\n

12-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>O metal tem menor calor espec\u00edfico que a madeira e tem maior facilidade em perder calor, se resfriando mais r\u00e1pido e liberando menos calor, pois, supondo que o bloco de madeira tenha calor espec\u00edfico dez vezes\u00a0 maior, a capacidade t\u00e9rmica do bloco de madeira\u00a0 ser\u00e1 dez\u00a0 maior que a do bloco de chumbo de mesma massa. <\/b><\/span><\/span><\/span><\/p>\n

Como os blocos sofrem a mesma queda de temperatura, o bloco de madeira ir\u00e1 fornecer dez vezes mais calor que o bloco de chumbo e assim sendo ir\u00e1 derreter mais gelo do que o bloco de chumbo\u00a0 —\u00a0<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>R- C<\/b><\/span><\/span><\/span><\/p>\n

13-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>Como o calor espec\u00edfico c \u00e9 o mesmo (\u00e1gua) e ambas recebem a mesma quantidade de calor Q aquele de menor massa sofrer\u00e1 maior eleva\u00e7\u00e3o de temperatura\u00a0 —\u00a0<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>R- C<\/b><\/span><\/span><\/span><\/p>\n

14-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>Pelo enunciado, toda pot\u00eancia e consequentemente toda energia eletromagn\u00e9tica liberada pelo telefone celular \u00e9 transformada em energia t\u00e9rmica provocando o aquecimento do l\u00edquido\u00a0 —\u00a0 P<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sub><\/span>=W\/\u2206t\u00a0 —\u00a0 1=W\/9×60\u00a0 —\u00a0 W=540J\u00a0 —\u00a0 W=Q=m.c.<\/b><\/span><\/span><\/span>\u2206\u03b8<\/b><\/span><\/span><\/span>\u00a0 —\u00a0 540=2.10<\/b><\/span><\/span><\/span>3<\/b><\/span><\/span><\/sup><\/span>.3,6.<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>\u2206\u03b8\u00a0 —\u00a0 \u2206\u03b8=540\/7,2.10<\/b><\/span><\/span><\/span>3<\/b><\/span><\/span><\/sup><\/span>\u00a0 —\u00a0 \u2206\u03b8=75.10<\/b><\/span><\/span><\/span>-3<\/b><\/span><\/span><\/sup><\/span>=7,5.10<\/b><\/span><\/span><\/span>-2<\/b><\/span><\/span><\/sup><\/span>\u00a0<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sup><\/span>C\u00a0 —\u00a0<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>R- A<\/b><\/span><\/span><\/span><\/p>\n

15-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>H\u00e1 dois sistemas de corpos a serem analisados, o constitu\u00eddo por \u00e1gua, l\u00e2mpada e meio (sistema 1) e o constitu\u00eddo por areia, l\u00e2mpada e meio (sistema 2)\u00a0 —\u00a0 os sistemas s\u00e3o termicamente isolados.\u00a0 —\u00a0 \u2211Q = 0\u00a0 —\u00a0 Q + Q<\/b><\/span><\/span><\/span>l\u00e2mpada<\/b><\/span><\/span><\/sub><\/span>\u00a0+ Q<\/b><\/span><\/span><\/span>meio<\/b><\/span><\/span><\/sub><\/span>\u00a0= 0<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/sub><\/span>\u00a0—\u00a0 n\u00e3o havendo<\/b><\/span><\/span><\/span><\/p>\n

mudan\u00e7a de estado f\u00edsico\u00a0 —\u00a0 m <\/b><\/span><\/span><\/span>\u22c5<\/b><\/span><\/span><\/span> c <\/b><\/span><\/span><\/span>\u22c5<\/b><\/span><\/span><\/span> \u0394\u03b8 + Q<\/b><\/span><\/span><\/span>l\u00e3mpada\u00a0<\/b><\/span><\/span><\/sub><\/span>+ Q<\/b><\/span><\/span><\/span>meio<\/b><\/span><\/span><\/sub><\/span>= 0 (1)<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/sub><\/span>\u00a0—\u00a0 pelo enunciado, a l\u00e2mpada fornece 3,6 kJ de energia\u00a0 — Q<\/b><\/span><\/span><\/span>l\u00e2mpada<\/b><\/span><\/span><\/sub><\/span>= \u20133,6 kJ\u00a0 —\u00a0 acertando as unidades dos calores espec\u00edficos.<\/b><\/span><\/span><\/span><\/p>\n

C<\/b><\/span><\/span><\/span>areia<\/b><\/span><\/span><\/sub><\/span>\u00a0= 0,2 cal\/g\u00b0C= 0,2 <\/b><\/span><\/span><\/span>\u22c5<\/b><\/span><\/span><\/span> 4 Jg\u00b0C = 0,8 <\/b><\/span><\/span><\/span>\u22c5<\/b><\/span><\/span><\/span> 10<\/b><\/span><\/span><\/span>-3<\/b><\/span><\/span><\/sup><\/span>\u00a0kJ\/g\u00b0C\u00a0 —\u00a0 C<\/b><\/span><\/span><\/span>\u00e1gua<\/b><\/span><\/span><\/sub><\/span>= 1 cal\/g\u00b0C = 4 <\/b><\/span><\/span><\/span>\u22c5<\/b><\/span><\/span><\/span> 10<\/b><\/span><\/span><\/span>-3<\/b><\/span><\/span><\/sup><\/span>\u00a0kJ\/g\u00b0C.<\/b><\/span><\/span><\/span><\/p>\n

Sistema 1<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/sub><\/span>\u00a0—\u00a0 m<\/b><\/span><\/span><\/span>\u00e1gua<\/b><\/span><\/span><\/sub><\/span>.c<\/b><\/span><\/span><\/span>\u00e1gua..<\/b><\/span><\/span><\/sub><\/span>\u0394\u03b8<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/sub><\/span>+ Q<\/b><\/span><\/span><\/span>l\u00e2mpada<\/b><\/span><\/span><\/sub><\/span>+ Q<\/b><\/span><\/span><\/span>meio<\/b><\/span><\/span><\/sub><\/span>\u00a0= 0\u00a0 —\u00a0 100 <\/b><\/span><\/span><\/span>\u22c5<\/b><\/span><\/span><\/span> 4 <\/b><\/span><\/span><\/span>\u22c5<\/b><\/span><\/span><\/span> 10<\/b><\/span><\/span><\/span>-3<\/b><\/span><\/span><\/sup><\/span>.(8)\u00a0 – 3,6 + Q<\/b><\/span><\/span><\/span>meio\u00a0<\/b><\/span><\/span><\/sub><\/span>=<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/sub><\/span>0\u00a0 —\u00a0 Q<\/b><\/span><\/span><\/span>meio<\/b><\/span><\/span><\/sub><\/span>= + 0,4kJ\u00a0 —\u00a0 sistema 2\u00a0 —\u00a0 m<\/b><\/span><\/span><\/span>areia<\/b><\/span><\/span><\/sub><\/span>.c<\/b><\/span><\/span><\/span>areia<\/b><\/span><\/span><\/sub><\/span>.\u0394\u03b8 + Q<\/b><\/span><\/span><\/span>l\u00e2mpada\u00a0<\/b><\/span><\/span><\/sub><\/span>+ Q<\/b><\/span><\/span><\/span>meio<\/b><\/span><\/span><\/sub><\/span>= 0\u00a0 —\u00a0 100 <\/b><\/span><\/span><\/span>\u22c5<\/b><\/span><\/span><\/span> 0,8 <\/b><\/span><\/span><\/span>\u22c5<\/b><\/span><\/span><\/span> 10<\/b><\/span><\/span><\/span>-3<\/b><\/span><\/span><\/sup><\/span>.(30) \u2013 3,6 + Q<\/b><\/span><\/span><\/span>meio<\/b><\/span><\/span><\/sub><\/span>=0\u00a0 —\u00a0<\/b><\/span><\/span><\/span><\/p>\n

Q<\/b><\/span><\/span><\/span>meio<\/b><\/span><\/span><\/sub><\/span>= + 1,2kJ\u00a0 —\u00a0<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>R- C<\/b><\/span><\/span><\/span><\/p>\n

 <\/p>\n

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

Resolu\u00e7\u00e3o Comentada \u00a0 F\u00edsica T\u00e9rmica Calor Sens\u00edvel (Espec\u00edfico) \u2013 Trocas de calor sem mudan\u00e7a de estado 01-\u00a0Observe os dados do gr\u00e1fico\u00a0 — \u00a0R- C 02- R- A\u00a0 —\u00a0 veja informa\u00e7\u00f5es abaixo: Nas regi\u00f5es des\u00e9rticas a amplitude t\u00e9rmica (diferen\u00e7a entre a m\u00e1xima e m\u00ednima temperaturas) \u00e9 bastante elevada e nas regi\u00f5es litor\u00e2neas ela \u00e9 bem menor devido ao alto calor espec\u00edfico<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":3753,"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-3755","page","type-page","status-publish","hentry"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/3755","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=3755"}],"version-history":[{"count":6,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/3755\/revisions"}],"predecessor-version":[{"id":10662,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/3755\/revisions\/10662"}],"up":[{"embeddable":true,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/3753"}],"wp:attachment":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/media?parent=3755"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}