{"id":2975,"date":"2017-05-24T02:43:57","date_gmt":"2017-05-24T02:43:57","guid":{"rendered":"http:\/\/fisicaevestibular.com.br\/novo\/?page_id=2975"},"modified":"2024-09-03T16:50:40","modified_gmt":"2024-09-03T16:50:40","slug":"resolucao-comentada-das-questoes-de-fisica-da-universidade-estadual-feira-de-santana-uefs-ba-017","status":"publish","type":"page","link":"https:\/\/fisicaevestibular.com.br\/novo\/universidades-2017\/uefs-2017\/resolucao-comentada-das-questoes-de-fisica-da-universidade-estadual-feira-de-santana-uefs-ba-017\/","title":{"rendered":"Resolu\u00e7\u00e3o comentada das quest\u00f5es de F\u00cdSICA da Universidade Estadual Feira de Santana (UEFS-BA-017)"},"content":{"rendered":"

Resolu\u00e7\u00e3o comentada das quest\u00f5es de F\u00cdSICA da <\/b><\/span><\/span><\/span><\/p>\n

Universidade Estadual Feira de Santana (UEFS-BA-017)<\/b><\/span><\/span><\/span><\/p>\n

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

Colocando as <\/b><\/span><\/span><\/span>for\u00e7as que agem em cada bloco <\/b><\/span><\/span><\/span>apenas na <\/b><\/span><\/span><\/span>dire\u00e7\u00e3o do movimento:<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Aplicando a <\/b><\/span><\/span><\/span>lei fundamental da Din\u00e2mica<\/b><\/span><\/span><\/span> para <\/b><\/span><\/span><\/span>cada bloco:<\/b><\/span><\/span><\/span><\/p>\n

C \"\" F<\/b><\/span><\/span><\/span>RC<\/b><\/span><\/span><\/sub><\/span> = m<\/b><\/span><\/span><\/span>C<\/b><\/span><\/span><\/sub><\/span>.a \"\" P<\/b><\/span><\/span><\/span>C<\/b><\/span><\/span><\/sub><\/span> \u2013 T<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span> = 5.a \"\" 50 \u2013 T<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span> = 5.a \"\" T<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span> = 50 \u2013 5a (I).<\/b><\/span><\/span><\/span><\/p>\n

B \"\" F<\/b><\/span><\/span><\/span>RB<\/b><\/span><\/span><\/sub><\/span> = m<\/b><\/span><\/span><\/span>B<\/b><\/span><\/span><\/sub><\/span>.a \"\" T<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span> \u2013 T<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span> – F<\/b><\/span><\/span><\/span>atB<\/b><\/span><\/span><\/sub><\/span> = 3.a \"\"<\/b><\/span><\/span><\/span> T<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span> \u2013 T<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span> – 6 = 3.a \"\" <\/b><\/span><\/span><\/span>T<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span> \u2013 T<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span> = 3.a + 6 (II) <\/b><\/span><\/span><\/span><\/p>\n

A \"\" F<\/b><\/span><\/span><\/span>RA<\/b><\/span><\/span><\/sub><\/span> = m<\/b><\/span><\/span><\/span>A<\/b><\/span><\/span><\/sub><\/span>.a \"\" T<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span> – F<\/b><\/span><\/span><\/span>atA<\/b><\/span><\/span><\/sub><\/span> = 2.a \"\" <\/b><\/span><\/span><\/span>T<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span> – 4 = 2.a \"\" <\/b><\/span><\/span><\/span>T<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span> = 2.a + 4 (III)<\/b><\/span><\/span><\/span><\/p>\n

Somando <\/b><\/span><\/span><\/span>simultaneamente (I), (II) e (III):<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

(IV) em (I) \"\" <\/b><\/span><\/span><\/span>30 = 50 \u2013 5a<\/b><\/span><\/span><\/span> \"\" a = 4 m\/s<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sup><\/span> (V) <\/b><\/span><\/span><\/span>(acelera\u00e7\u00e3o de cada bloco).<\/b><\/span><\/span><\/span><\/p>\n

(V) em (III) \"\" <\/b><\/span><\/span><\/span>T<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span> = 2.4 + 4 \"\" <\/b><\/span><\/span><\/span>T<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span> = 12 N.<\/b><\/span><\/span><\/span><\/p>\n

R- 04<\/b><\/span><\/span><\/span><\/p>\n

02- <\/b><\/span><\/span><\/span>Quando <\/b><\/span><\/span><\/span>a mola <\/b><\/span><\/span><\/span>de <\/b><\/span><\/span><\/span>constante el\u00e1stica k = 4 N\/cm = 400 N\/m \u00e9 comprimida<\/b><\/span><\/span><\/span> de <\/b><\/span><\/span><\/span>x = 12cm = 0,12 m <\/b><\/span><\/span><\/span>(ponto <\/b><\/span><\/span><\/span>A<\/b><\/span><\/span><\/span>) ela s\u00f3 <\/b><\/span><\/span><\/span>possui armazenada energia potencial el\u00e1stica (E<\/b><\/span><\/span><\/span>pe<\/b><\/span><\/span><\/sub><\/span> = k.\"\"<\/b><\/span><\/span><\/span>) <\/b><\/span><\/span><\/span>pois, como V<\/b><\/span><\/span><\/span> <\/b>= 0 a <\/b><\/span><\/span><\/span>energia cin\u00e9tica <\/b><\/span><\/span><\/span>\u00e9 <\/b><\/span><\/span><\/span>nula (E<\/b><\/span><\/span><\/span>c<\/b><\/span><\/span><\/sub><\/span> = 0) <\/b><\/span><\/span><\/span>e como a <\/b><\/span><\/span><\/span>altura n\u00e3o varia <\/b><\/span><\/span><\/span>a <\/b><\/span><\/span><\/span>energia potencial gravitacional tamb\u00e9m \u00e9 nula (E<\/b><\/span><\/span><\/span>pg<\/b><\/span><\/span><\/sub><\/span> = 0).<\/b><\/span><\/span><\/span><\/p>\n

A <\/b><\/span><\/span><\/span>energia mec\u00e2nica total em A, E<\/b><\/span><\/span><\/span>mA<\/b><\/span><\/span><\/sub><\/span> <\/b>\u00e9 apenas a <\/b><\/span><\/span><\/span>energia potencial el\u00e1stica<\/b><\/span><\/span><\/span> \"\" <\/b><\/span><\/span><\/span>E<\/b><\/span><\/span><\/span>mA<\/b><\/span><\/span><\/sub><\/span> = <\/b><\/span><\/span><\/span>E<\/b><\/span><\/span><\/span>pe<\/b><\/span><\/span><\/sub><\/span> = k.\"\"<\/b><\/span><\/span><\/span> =<\/b><\/span><\/span><\/span> <\/b>400.\"\"<\/b><\/span><\/span><\/span> \"\" <\/b><\/span><\/span><\/span>E<\/b><\/span><\/span><\/span>mA<\/b><\/span><\/span><\/sub><\/span> = 200.0,0144<\/b><\/span><\/span><\/span> \"\" <\/b><\/span><\/span><\/span>E<\/b><\/span><\/span><\/span>mA<\/b><\/span><\/span><\/sub><\/span> = 2,88 J.<\/b><\/span><\/span><\/span><\/p>\n

Depois que o bloco \u00e9 liberado no ponto A ele se desloca at\u00e9 atingir o ponto B onde para (V = 0) na altura H.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Em <\/b><\/span><\/span><\/span>B, onde a altura H \u00e9 m\u00e1xima,<\/b><\/span><\/span><\/span> suas <\/b><\/span><\/span><\/span>energias potencial el\u00e1stica e cin\u00e9tica s\u00e3o nulas, <\/b><\/span><\/span><\/span>sobrando apenas <\/b><\/span><\/span><\/span>a energia potencial gravitacional (E<\/b><\/span><\/span><\/span>pg<\/b><\/span><\/span><\/sub><\/span> = m.g.H) que \u00e9 a mec\u00e2nica em B. <\/b><\/span><\/span><\/span><\/p>\n

E<\/b><\/span><\/span><\/span>mB<\/b><\/span><\/span><\/sub><\/span> = E<\/b><\/span><\/span><\/span>pg<\/b><\/span><\/span><\/sub><\/span> = m.g.H<\/b><\/span><\/span><\/span> = 1,2.10.H <\/b><\/span><\/span><\/span>= 12H.<\/b><\/span><\/span><\/span><\/p>\n

Sendo as <\/b><\/span><\/span><\/span>for\u00e7as dissipativas desprezadas<\/b><\/span><\/span><\/span>, a <\/b><\/span><\/span><\/span>energia mec\u00e2nica se conserva \"\"<\/b><\/span><\/span><\/span> <\/b>E<\/b><\/span><\/span><\/span>mA<\/b><\/span><\/span><\/sub><\/span> = E<\/b><\/span><\/span><\/span>mB<\/b><\/span><\/span><\/sub><\/span> \"\"<\/b><\/span><\/span><\/span> 2,88 = 12H \"\" H = \"\"<\/b><\/span><\/span><\/span> \"\" <\/b><\/span><\/span><\/span>H <\/b><\/span><\/span><\/span>= 0,24 m <\/b><\/span><\/span><\/span>= 24 cm.<\/b><\/span><\/span><\/span><\/p>\n

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

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

\"\"<\/p>\n

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

Express\u00e3o matem\u00e1tica da dilat\u00e7\u00e3o linear de um s\u00f3lido<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Sendo:<\/b><\/span><\/span><\/p>\n

\u0394L<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span>\u00a0\"\"<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>dilata\u00e7\u00e3o linear<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>(de quanto dilatou o comprimento ou uma dimens\u00e3o)<\/b><\/span><\/span><\/span><\/p>\n

\u03b1<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span>\u00a0\"\"<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>coeficiente de dilata\u00e7\u00e3o linear m\u00e9dio<\/b><\/span><\/span><\/span>, <\/b><\/span><\/span>caracter\u00edstica do material que constitui a barra.<\/b><\/span><\/span><\/span><\/p>\n

Lo<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span>\u00a0\"\"<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>comprimento inicial<\/b><\/span><\/span><\/span><\/p>\n

L<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span>\u00a0\"\"<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>comprimento final<\/b><\/span><\/span><\/span><\/p>\n

\u0394t<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span>\u00a0\"\"\u00a0<\/b><\/span><\/span><\/span>intervalo de temperatura<\/b><\/span><\/span><\/span><\/p>\n

S\u00e3o dados \"\"<\/b><\/span><\/span><\/span> <\/b>L<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sub><\/span> =<\/b><\/span><\/span><\/span> 20,5 m \"\" \"\"<\/b><\/span><\/span><\/span> = <\/b><\/span><\/span><\/span>1,7.10<\/b><\/span><\/span><\/span>-5<\/b><\/span><\/span><\/sup><\/span>\/<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sup><\/span>C \"\" <\/b><\/span><\/span><\/span>\u0394t = <\/b><\/span><\/span><\/span>(40 \u2013 20) = 20 <\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sup><\/span>C.<\/b><\/span><\/span><\/span><\/p>\n

\u2206L = L<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sub><\/span>.\"\"<\/b><\/span><\/span><\/span> \u0394t \"\" <\/b><\/span><\/span><\/span>\u2206L = 20,5.1,7.10<\/b><\/span><\/span><\/span>-5<\/b><\/span><\/span><\/sup><\/span>.20 \"\" \u2206L = 697.10<\/b><\/span><\/span><\/span>-5<\/b><\/span><\/span><\/sup><\/span> m = 6,97.10<\/b><\/span><\/span><\/span>-3<\/b><\/span><\/span><\/sup><\/span> m \"\" <\/b><\/span><\/span><\/span>\u2206L = 6,97 mm<\/b><\/span><\/span><\/span><\/p>\n

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

05- <\/b><\/span><\/span><\/span>A <\/b><\/span><\/span><\/span>troca de calor<\/b><\/span><\/span><\/span> \u00e9 entre o <\/b><\/span><\/span><\/span>calor\u00edmetro de capacidade t\u00e9rmica C = 300 ca\/<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sup><\/span>C com temperatura inicial de t<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sub><\/span> =20 <\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sup><\/span>C<\/b><\/span><\/span><\/span>, a <\/b><\/span><\/span><\/span>massa m<\/b><\/span><\/span><\/span>a<\/b><\/span><\/span><\/sub><\/span> = 200 g de \u00e1gua de calor espec\u00edfico c<\/b><\/span><\/span><\/span>a<\/b><\/span><\/span><\/sub><\/span> = 1 cal\/g<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sup><\/span>C com temperatura inicial t<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sub><\/span> = 20 <\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sup><\/span>C <\/b><\/span><\/span><\/span>e o <\/b><\/span><\/span><\/span>bloco de massa m<\/b><\/span><\/span><\/span>b<\/b><\/span><\/span><\/sub><\/span> = 1000 g, calor espec\u00edfico c<\/b><\/span><\/span><\/span>b<\/b><\/span><\/span><\/sub><\/span> = 0,25 cal\/g<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sup><\/span>C e temperatura inicial t<\/b><\/span><\/span><\/span>ob<\/b><\/span><\/span><\/sub><\/span> = 50 <\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sup><\/span>C.<\/b><\/span><\/span><\/span><\/p>\n

Ap\u00f3s as trocas de calor<\/b><\/span><\/span><\/span> entre eles <\/b><\/span><\/span><\/span>todos ter\u00e3o a mesma temperatura t <\/b><\/span><\/span><\/span>(temperatura de equil\u00edbrio t\u00e9rmico).<\/b><\/span><\/span><\/span><\/p>\n

A <\/b><\/span><\/span><\/span>soma das quantidades de calor que eles trocam entre si deve ser nula.<\/b><\/span><\/span><\/span><\/p>\n

C.(t \u2013 t<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sub><\/span>) + m<\/b><\/span><\/span><\/span>a<\/b><\/span><\/span><\/sub><\/span>.c<\/b><\/span><\/span><\/span>a<\/b><\/span><\/span><\/sub><\/span>.(t \u2013 t<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sub><\/span>) + m<\/b><\/span><\/span><\/span>b<\/b><\/span><\/span><\/sub><\/span>.c<\/b><\/span><\/span><\/span>b<\/b><\/span><\/span><\/sub><\/span>.(t \u2013 t<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sub><\/span>) = 0 \"\"<\/b><\/span><\/span><\/span> 300.(t \u2013 20) + 200.1.(t \u2013 20) + 1000.0,25.(t \u2013 50) = 0 \"\" 300t \u2013 6000 + 200t \u2013 4000 +250t \u2013 12500 = 0 \"\" 750t = 22500 \"\" t = \"\" \"\" <\/b><\/span><\/span><\/span>t = 30 <\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sup><\/span>C.<\/b><\/span><\/span><\/span><\/p>\n

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

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

Lei de Snell-Descartes<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

n<\/b><\/span><\/span><\/span>ar<\/b><\/span><\/span><\/sub><\/span>.sen\"\"<\/b><\/span><\/span><\/span> = n<\/b><\/span><\/span><\/span>.<\/b><\/span><\/span><\/sub><\/span>sen\"\"<\/b><\/span><\/span><\/span> \"\"<\/b><\/span><\/span><\/sub><\/span> <\/b> 1.0,5 = n.0,87 \"\" n = \"\" \"\" <\/b><\/span><\/span><\/span>n = 1,74.<\/b><\/span><\/span><\/span><\/p>\n

R- 04<\/b><\/span><\/span><\/span><\/p>\n

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

Express\u00e3o matem\u00e1tica do empuxo quando imerso num l\u00edquido<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

R – 01<\/b><\/span><\/span><\/span><\/p>\n

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

IM\u00c3S E CAMPO MAGN\u00c9TICO<\/b><\/span><\/span><\/span><\/p>\n

IM\u00c3S<\/b><\/span><\/span><\/span><\/p>\n

Desde a\u00a0<\/b><\/span><\/span><\/span>antiguidade se conhecia um mineral,\u00a0<\/b><\/span><\/span><\/span>hoje denominado\u00a0<\/b><\/span><\/span><\/span>magnetita, <\/b><\/span><\/span><\/span>composto basicamente por\u00a0<\/b><\/span><\/span><\/span>\u00f3xido de ferro (Fe3O4)\u00a0<\/b><\/span><\/span><\/span>que\u00a0<\/b><\/span><\/span><\/span>possu\u00eda propriedade de atrair alguns minerais como o ferro, o n\u00edquel <\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

e o cobalto e pedras de \u00f3xidos de ferro e que s\u00e3o denominadas de\u00a0im\u00e3s naturais.<\/b><\/span><\/span><\/span><\/p>\n

Essa propriedade recebe o nome de magnetismo <\/b><\/span><\/span><\/span>e as <\/b><\/span><\/span><\/span>regi\u00f5es do im\u00e3 onde as\u00a0propriedades magn\u00e9ticas s\u00e3o mais intensas\u00a0s\u00e3o denominadas de\u00a0polos do im\u00e3.<\/b><\/span><\/span><\/span><\/p>\n

R- 05<\/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 das quest\u00f5es de F\u00cdSICA da Universidade Estadual Feira de Santana (UEFS-BA-017) 01- Colocando as for\u00e7as que agem em cada bloco apenas na dire\u00e7\u00e3o do movimento: Aplicando a lei fundamental da Din\u00e2mica para cada bloco: C FRC = mC.a PC \u2013 T1 = 5.a 50 \u2013 T1 = 5.a T1 = 50 \u2013 5a (I). B FRB = mB.a<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":2973,"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-2975","page","type-page","status-publish","hentry"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/2975","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=2975"}],"version-history":[{"count":2,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/2975\/revisions"}],"predecessor-version":[{"id":2977,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/2975\/revisions\/2977"}],"up":[{"embeddable":true,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/2973"}],"wp:attachment":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/media?parent=2975"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}