{"id":2768,"date":"2017-03-15T04:46:51","date_gmt":"2017-03-15T04:46:51","guid":{"rendered":"http:\/\/fisicaevestibular.com.br\/novo\/?page_id=2768"},"modified":"2024-09-03T16:56:05","modified_gmt":"2024-09-03T16:56:05","slug":"resolucao-comentada-das-questoes-de-fisica-da-universidade-estadual-do-rio-de-janeiro-uerj-2017","status":"publish","type":"page","link":"https:\/\/fisicaevestibular.com.br\/novo\/universidades-2017\/uerj-2017\/resolucao-comentada-das-questoes-de-fisica-da-universidade-estadual-do-rio-de-janeiro-uerj-2017\/","title":{"rendered":"Resolu\u00e7\u00e3o comentada das quest\u00f5es de F\u00edsica da Universidade Estadual do Rio de Janeiro (UERJ) \u2013 2017"},"content":{"rendered":"

Resolu\u00e7\u00e3o comentada das quest\u00f5es de F\u00edsica da <\/span><\/span><\/span><\/p>\n

Universidade Estadual do Rio de Janeiro (UERJ) \u2013 2017<\/span><\/span><\/span><\/p>\n

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

For\u00e7as no Movimento Circular em trajet\u00f3rias Curvas<\/b><\/span><\/span><\/p>\n

\u00a0<\/span>Considere um\u00a0<\/b><\/span><\/span>m\u00f3vel de massa\u00a0<\/b><\/span><\/span>m<\/b><\/span><\/span>\u00a0descrevendo um\u00a0<\/b><\/span><\/span>movimento circular uniforme MCU, onde a<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>velocidade escalar, tangencial ou linear\u00a0<\/b><\/span><\/span>V<\/b><\/span><\/span>\u00a0e a angular\u00a0<\/b><\/span><\/span>W<\/b><\/span><\/span>\u00a0\u00e9 constante, numa trajet\u00f3ria plana, de raio\u00a0<\/b><\/span><\/span>R.<\/b><\/span><\/span><\/p>\n

Conforme a\u00a0<\/b><\/span><\/span>cinem\u00e1tica vetorial<\/b><\/span><\/span>, devido ao fato de o\u00a0<\/b><\/span><\/span>vetor velocidade<\/b><\/span><\/span>\u00a0ser sempre\u00a0<\/b><\/span><\/span>tangente \u00e0 trajet\u00f3ria<\/b><\/span><\/span>\u00a0em cada ponto, esse vetor velocidade <\/b><\/span><\/span>variar\u00e1 continuamente\u00a0<\/b><\/span><\/span>e far\u00e1\u00a0<\/b><\/span><\/span>surgir\u00a0<\/b><\/span><\/span>sobre o m\u00f3vel uma<\/b><\/span><\/span> <\/b>acelera\u00e7\u00e3o centr\u00edpeta<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>(a<\/b><\/span><\/span>c<\/b><\/span><\/sub><\/span>) com as\u00a0<\/b><\/span><\/span>seguintes caracter\u00edsticas:<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

02- <\/span><\/span><\/span>C\u00e1lculo da <\/b><\/span><\/span><\/span>resist\u00eancia equivalente na sequ\u00eancia abaixo:<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Corrente el\u00e9trica total i \"\" R<\/b><\/span><\/span><\/span>eq<\/b><\/span><\/span><\/sub><\/span> = \"\"<\/b><\/span><\/span><\/span> \"\" 4 = \"\" \"\" i = \"\" \"\" <\/b><\/span><\/span><\/span>i = 3 A<\/b><\/span><\/span><\/span><\/p>\n

03- <\/span><\/span><\/span>A express\u00e3o da <\/b><\/span><\/span><\/span>quantidade de movimento <\/b><\/span><\/span><\/span>de um <\/b><\/span><\/span><\/span>corpo de massa m e velocidade V <\/b><\/span><\/span><\/span>\u00e9 fornecida por <\/b><\/span><\/span><\/span><\/p>\n

Q = m.V.<\/b><\/span><\/span><\/span><\/p>\n

Q<\/b><\/span><\/span><\/span>elefante<\/b><\/span><\/span><\/sub><\/span> \"\" <\/b><\/span><\/span><\/sub><\/span>Q<\/b><\/span><\/span><\/span>e<\/b><\/span><\/span><\/sub><\/span> = m<\/b><\/span><\/span><\/span>e<\/b><\/span><\/span><\/sub><\/span>.V<\/b><\/span><\/span><\/span>e<\/b><\/span><\/span><\/sub><\/span> <\/b>= 4860×40 = <\/b><\/span><\/span><\/span>194 400 kg.km\/h<\/b><\/span><\/span><\/span><\/p>\n

Q<\/b><\/span><\/span><\/span>le\u00e3o <\/b><\/span><\/span><\/sub><\/span> \"\" <\/b><\/span><\/span><\/sub><\/span>Q<\/b><\/span><\/span><\/span>l<\/b><\/span><\/span><\/sub><\/span> = m<\/b><\/span><\/span><\/span>l<\/b><\/span><\/span><\/sub><\/span>.V<\/b><\/span><\/span><\/span>l<\/b><\/span><\/span><\/sub><\/span> <\/b>= 200×81 <\/b><\/span><\/span><\/span>= 16 200 kg.km\/h<\/b><\/span><\/span><\/span><\/p>\n

Raz\u00e3o \"\"<\/b><\/span><\/span><\/span> R = \"\"<\/b><\/span><\/span><\/span> \"\" <\/b><\/span><\/span><\/span>R = 12<\/b><\/span><\/span><\/span><\/p>\n

04- <\/span><\/span><\/span>V<\/b><\/span><\/span><\/span>P<\/b><\/span><\/span><\/sub><\/span> = \"\"<\/b><\/span><\/span><\/span> \"\"<\/b><\/span><\/span><\/span> 8 = \"\" \"\" t\u2019 = \"\" \"\" <\/b><\/span><\/span><\/span>t\u2019 = 150 s<\/b><\/span><\/span><\/span><\/p>\n

V<\/b><\/span><\/span><\/span>S<\/b><\/span><\/span><\/sub><\/span> = \"\"<\/b><\/span><\/span><\/span> \"\" 5 = \"\" \"\" t\u2019\u2019 = \"\" \"\" <\/b><\/span><\/span><\/span>t\u2019\u2019 = 240 s<\/b><\/span><\/span><\/span><\/p>\n

\u2206t = <\/b><\/span><\/span><\/span>240 \u2013 150 \"\" <\/b><\/span><\/span><\/span>\u2206t = 90 s<\/b><\/span><\/span><\/span><\/p>\n

05- \"\"<\/span><\/span><\/span><\/p>\n

Como o <\/b><\/span><\/span><\/span>enunciado afirma <\/b><\/span><\/span><\/span>que a <\/b><\/span><\/span><\/span>imagem conjugada <\/b><\/span><\/span><\/span>est\u00e1 situada<\/b><\/span><\/span><\/span> <\/b>no <\/b><\/span><\/span><\/span>plano focal (f) do espelho \"\" <\/b><\/span><\/span><\/span><\/p>\n

a <\/b><\/span><\/span><\/span>dist\u00e2ncia da imagem ao espelho <\/b><\/span><\/span><\/span>P<\/b><\/span><\/span><\/span>\u2019<\/b><\/span><\/span><\/span> \u00e9 a <\/b><\/span><\/span><\/span>pr\u00f3pria dist\u00e2ncia focal <\/b><\/span><\/span><\/span>f<\/b><\/span><\/span><\/span> <\/b>do espelho \"\" <\/b><\/span><\/span><\/span>P\u2019 = f = 0,2 m.<\/b><\/span><\/span><\/span><\/p>\n

\"\" = \"\"<\/b><\/span><\/span><\/span> \"\" \"\" = \"\" \"\" i = – \"\" \"\" i = – 0,04m \"\" <\/b><\/span><\/span><\/span>i = – 4 cm (a imagem tem <\/b><\/span><\/span><\/span>altura de 4 cm<\/b><\/span><\/span><\/span> e \u00e9 invertida em rela\u00e7\u00e3o ao objeto)<\/b><\/span><\/span><\/span><\/p>\n

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

\"\"<\/p>\n

Figura 2<\/b><\/span><\/span><\/span> \"\" <\/b><\/span><\/span><\/span>T<\/b><\/span><\/span><\/span>CBh<\/b><\/span><\/span><\/sub><\/span> = T<\/b><\/span><\/span><\/span>CB<\/b><\/span><\/span><\/sub><\/span>.cos30<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sup><\/span> <\/b>= \"\"<\/b><\/span><\/span><\/span>T<\/b><\/span><\/span><\/span>CB<\/b><\/span><\/span><\/sub><\/span>)\/2 \"\" <\/b><\/span><\/span><\/span>T<\/b><\/span><\/span><\/span>CBv<\/b><\/span><\/span><\/sub><\/span> <\/b>= T<\/b><\/span><\/span><\/span>CB<\/b><\/span><\/span><\/sub><\/span>.sen30<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sup><\/span> <\/b>= <\/b><\/span><\/span><\/span>T<\/b><\/span><\/span><\/span>CB<\/b><\/span><\/span><\/sub><\/span>\/2.<\/b><\/span><\/span><\/span><\/p>\n

Figura 3<\/b><\/span><\/span><\/span> \"\" <\/b><\/span><\/span><\/span>equil\u00edbrio na vertical \"\"<\/b><\/span><\/span><\/span> <\/b>T<\/b><\/span><\/span><\/span>CBv<\/b><\/span><\/span><\/sub><\/span> = P \"\"<\/b><\/span><\/span><\/span> T<\/b><\/span><\/span><\/span>CB<\/b><\/span><\/span><\/sub><\/span>\/2 = mg = 100.10 \"\" T<\/b><\/span><\/span><\/span>CB<\/b><\/span><\/span><\/sub><\/span>\/2 = 1000 \"\" <\/b><\/span><\/span><\/span>T<\/b><\/span><\/span><\/span>CB<\/b><\/span><\/span><\/sub><\/span> = 2000N. <\/b><\/span><\/span><\/span><\/p>\n

Figura 3 \"\" equil\u00edbrio na horizontal \"\" T<\/b><\/span><\/span><\/span>CBh<\/b><\/span><\/span><\/sub><\/span> = T<\/b><\/span><\/span><\/span>AB<\/b><\/span><\/span><\/sub><\/span> \"\"<\/b><\/span><\/span><\/span> \"\"<\/b><\/span><\/span><\/span>T<\/b><\/span><\/span><\/span>CB<\/b><\/span><\/span><\/sub><\/span>)\/2 = <\/b><\/span><\/span><\/span>T<\/b><\/span><\/span><\/span>AB<\/b><\/span><\/span><\/sub><\/span> \"\" \"\"<\/b><\/span><\/span><\/span>)\/2 = <\/b><\/span><\/span><\/span>T<\/b><\/span><\/span><\/span>AB<\/b><\/span><\/span><\/sub><\/span> \"\" <\/b><\/span><\/span><\/span><\/p>\n

T<\/b><\/span><\/span><\/span>AB<\/b><\/span><\/span><\/sub><\/span> = 1000\"\"<\/b><\/span><\/span><\/span><\/p>\n

07- <\/span><\/span><\/span>Observe na <\/b><\/span><\/span><\/span>figura que o comprimento de onda (<\/b><\/span><\/span><\/span>\u0001), <\/b><\/span><\/span><\/span>que <\/b><\/span><\/span><\/span>correspode \u00e0 dist\u00e2ncia entre dois pontos <\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

consecutivos em <\/b><\/span><\/span><\/span>concord\u00e2ncia de fase, como por exemplo, duas cristas, vale <\/b><\/span><\/span><\/span>\u0001<\/b><\/span><\/span><\/span> = 8 cm = 0,08 m.<\/b><\/span><\/span><\/span><\/p>\n

Aplicando a <\/b><\/span><\/span><\/span>equa\u00e7\u00e3o fundamental da ondulat\u00f3ria V = <\/b><\/span><\/span><\/span>\u0001.f \"\"<\/b><\/span><\/span><\/span> 0,48 = 0,08.f \"\" f = \"\"<\/b><\/span><\/span><\/span> \"\" <\/b><\/span><\/span><\/span>f = 6 Hz<\/b><\/span><\/span><\/span><\/p>\n

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

Pot\u00eancia = \"\"<\/b><\/span><\/span><\/span> \"\" 4000 = \"\"<\/b><\/span><\/span><\/span> \"\" <\/b><\/span><\/span><\/span>W = 4000 J \"\"<\/b><\/span><\/span><\/span> <\/b>1 cal = 4 J \"\"<\/b><\/span><\/span><\/span> W = \"\" \"\" <\/b><\/span><\/span><\/span>W = Q =1 000 cal<\/b><\/span><\/span><\/span> \"\" <\/b><\/span><\/span><\/span>P = \"\"<\/b><\/span><\/span><\/span> \"\" P = \"\"<\/b><\/span><\/span><\/span> \"\" <\/b><\/span><\/span><\/span>P = 1000 cal\/s. \"\"P =\"\" \"\"<\/b><\/span><\/span><\/span> 1000 = \"\" \"\" 1000 = \"\"<\/b><\/span><\/span><\/span> \"\"<\/b><\/span><\/span><\/span> \"\"<\/b><\/span><\/span><\/span> = vaz\u00e3o = \"\" \"\"<\/b><\/span><\/span><\/span> = 25 g\/s = 25.\"\" = \"\" = \"\" = \"\" \"\" considerando <\/b><\/span><\/span><\/span>densidade da \u00e1gua d = \"\"<\/b><\/span><\/span><\/span> \"\"<\/b><\/span><\/span><\/span> = \"\" <\/b><\/span><\/span><\/span><\/p>\n

09- <\/span><\/span><\/span>Dados:<\/b><\/span><\/span><\/span> <\/b>massa do reboque<\/b><\/span><\/span><\/span> \"\" <\/b><\/span><\/span><\/span>m =<\/b><\/span><\/span><\/span> 16.10<\/b><\/span><\/span><\/span>3<\/b><\/span><\/span><\/sup><\/span> kg \"\" <\/b><\/span><\/span><\/span>acelera\u00e7\u00e3o do reboque \"\" a = <\/b><\/span><\/span><\/span>200 cm\/s<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sup><\/span> = 200.10<\/b><\/span><\/span><\/span>-2<\/b><\/span><\/span><\/sup><\/span>m\/s<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sup><\/span> <\/b><\/p>\n

\"\" a = 2 m\/s<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sup><\/span>.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

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

\"\"<\/p>\n

Dados: B = <\/b><\/span><\/span><\/span>2.10-3 T, <\/b><\/span><\/span><\/span>i =<\/b><\/span><\/span><\/span> 300 mA = 300.10<\/b><\/span><\/span><\/span>-3<\/b><\/span><\/span><\/sup><\/span> = 3.10<\/b><\/span><\/span><\/span>-1<\/b><\/span><\/span><\/sup><\/span> A, <\/b><\/span><\/span><\/span>L =<\/b><\/span><\/span><\/span> 50 cm = 5.10<\/b><\/span><\/span><\/span>-1<\/b><\/span><\/span><\/sup><\/span> m e \"\"<\/b><\/span><\/span><\/span> =<\/b><\/span><\/span><\/span> 90<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sup><\/span>.<\/b><\/span><\/span><\/span><\/p>\n

F<\/b><\/span><\/span><\/span>m<\/b><\/span><\/span><\/sub><\/span> = B.i.L.sen\"\" <\/b><\/span><\/span><\/span>= 2.10<\/b><\/span><\/span><\/span>-3<\/b><\/span><\/span><\/sup><\/span>.3.10<\/b><\/span><\/span><\/span>-1<\/b><\/span><\/span><\/sup><\/span>.5.10<\/b><\/span><\/span><\/span>-1<\/b><\/span><\/span><\/sup><\/span>.sen90<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sup><\/span> = 30.10<\/b><\/span><\/span><\/span>-5<\/b><\/span><\/span><\/sup><\/span>.1 \"\" <\/b><\/span><\/span><\/span>F<\/b><\/span><\/span><\/span>m<\/b><\/span><\/span><\/sub><\/span> = 3,0.10<\/b><\/span><\/span><\/span>-4<\/b><\/span><\/span><\/sup><\/span> N<\/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\u00edsica da Universidade Estadual do Rio de Janeiro (UERJ) \u2013 2017 01- For\u00e7as no Movimento Circular em trajet\u00f3rias Curvas \u00a0Considere um\u00a0m\u00f3vel de massa\u00a0m\u00a0descrevendo um\u00a0movimento circular uniforme MCU, onde a\u00a0velocidade escalar, tangencial ou linear\u00a0V\u00a0e a angular\u00a0W\u00a0\u00e9 constante, numa trajet\u00f3ria plana, de raio\u00a0R. Conforme a\u00a0cinem\u00e1tica vetorial, devido ao fato de o\u00a0vetor velocidade\u00a0ser sempre\u00a0tangente \u00e0 trajet\u00f3ria\u00a0em cada ponto,<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":2766,"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-2768","page","type-page","status-publish","hentry"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/2768","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=2768"}],"version-history":[{"count":2,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/2768\/revisions"}],"predecessor-version":[{"id":2770,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/2768\/revisions\/2770"}],"up":[{"embeddable":true,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/2766"}],"wp:attachment":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/media?parent=2768"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}