{"id":3106,"date":"2017-07-30T21:55:57","date_gmt":"2017-07-30T21:55:57","guid":{"rendered":"http:\/\/fisicaevestibular.com.br\/novo\/?page_id=3106"},"modified":"2024-09-03T17:20:56","modified_gmt":"2024-09-03T17:20:56","slug":"resolucao-comentada-das-questoes-de-fisica-da-ufsc-sc-2017","status":"publish","type":"page","link":"https:\/\/fisicaevestibular.com.br\/novo\/universidades-2017\/ufsc-2017\/resolucao-comentada-das-questoes-de-fisica-da-ufsc-sc-2017\/","title":{"rendered":"Resolu\u00e7\u00e3o comentada das quest\u00f5es de F\u00cdSICA da UFSC \u2013 SC- 2017"},"content":{"rendered":"

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

UFSC \u2013 SC- 2017<\/b><\/span><\/span><\/span><\/p>\n

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

01. Falsa \"\"<\/b><\/span><\/span><\/span> <\/b><\/p>\n

Em todo <\/b><\/span><\/span>lan\u00e7amento obl\u00edquo<\/b><\/span><\/span> o<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>vetor velocidade\u00a0\"\"\u00a0\u00e9 sempre tangente \u00e0 trajet\u00f3ria em cada ponto e sempre decomposto em\u00a0\"\"e\u00a0\"\".<\/b><\/span><\/span><\/span><\/span><\/p>\n

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

\"\"<\/p>\n

\u00a0<\/span>Em<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>qualquer ponto \u00e9 v\u00e1lida a rela\u00e7\u00e3o V<\/b><\/span><\/span>2<\/b><\/span><\/sup><\/span>\u00a0= V<\/b><\/span><\/span>x<\/b><\/span><\/sub><\/span>2<\/b><\/span><\/sup><\/span>\u00a0+ V<\/b><\/span><\/span>y<\/b><\/span><\/sub><\/span>2<\/b><\/span><\/sup><\/span>.<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>Observe que\u00a0no <\/b><\/span><\/span>ponto mais alto da trajet\u00f3ria<\/b><\/span><\/span> a <\/b><\/span><\/span>velocidade vetorial\u00a0\"\"\u00a0n\u00e3o \u00e9 nula<\/b><\/span><\/span>, tem intensidade m\u00ednima e \u00e9 igual \u00e0 componente horizontal, ou seja,\u00a0\"\".<\/b><\/span><\/span><\/span><\/span><\/p>\n

02. Correta \"\"<\/b><\/span><\/span><\/span> o <\/b><\/span><\/span><\/span>per\u00edodo de oscila\u00e7\u00e3o <\/b><\/span><\/span><\/span>de um <\/b><\/span><\/span><\/span>p\u00eandulo simples <\/b><\/span><\/span><\/span>\u00e9 fornecido <\/b><\/span><\/span><\/span>por T = 2\"\"<\/b><\/span><\/span><\/span> . <\/b><\/span><\/span><\/span><\/p>\n

Observe <\/b><\/span><\/span><\/span>nessa express\u00e3o <\/b><\/span><\/span><\/span>que o <\/b><\/span><\/span><\/span>per\u00edodo T <\/b><\/span><\/span><\/span>e a raiz quadrada do <\/b><\/span><\/span><\/span>comprimento L do fio (teia) s\u00e3o diretamente proporcionais.<\/b><\/span><\/span><\/span><\/p>\n

04. Falsa \"\"<\/b><\/span><\/span><\/span> como ele \u00e9 <\/b><\/span><\/span><\/span>el\u00e1stico <\/b><\/span><\/span><\/span>ele <\/b><\/span><\/span><\/span>armazena energia potencial el\u00e1stica <\/b><\/span><\/span><\/span>fornecida por <\/b><\/span><\/span><\/span>E<\/b><\/span><\/span><\/span>pe<\/b><\/span><\/span><\/sub><\/span> = k.x<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sup><\/span>\/2.<\/b><\/span><\/span><\/span><\/p>\n

08. Correta \"\"<\/b><\/span><\/span><\/span> a <\/b><\/span><\/span><\/span>intensidade<\/b><\/span><\/span><\/span> do <\/b><\/span><\/span><\/span>Empuxo (for\u00e7a vertical e para cima <\/b><\/span><\/span><\/span>aplicada pelo <\/b><\/span><\/span><\/span>l\u00edquido sobre <\/b><\/span><\/span><\/span>a <\/b><\/span><\/span><\/span>pedra <\/b><\/span><\/span><\/span>\u00e9 fornecido por <\/b><\/span><\/span><\/span>E = d<\/b><\/span><\/span><\/span>l\u00edquido<\/b><\/span><\/span><\/sub><\/span>.g.V<\/b><\/span><\/span><\/span>imerso<\/b><\/span><\/span><\/sub><\/span> <\/b>e, por essa express\u00e3o, <\/b><\/span><\/span><\/span>quanto maior a densidade do l\u00edquido maior ser\u00e1 o empuxo, fazendo com que o peso aparente da pedra no mar morto (mais denso) seja menor.<\/b><\/span><\/span><\/span><\/p>\n

16. Correta \"\"<\/b><\/span><\/span><\/span> quando ele <\/b><\/span><\/span><\/span>corre <\/b><\/span><\/span><\/span>ele <\/b><\/span><\/span><\/span>aumenta o movimento vibrat\u00f3rio das part\u00edculas de seu corpo, aumentando <\/b><\/span><\/span><\/span>assim a <\/b><\/span><\/span><\/span>energia cin\u00e9tica <\/b><\/span><\/span><\/span>que \u00e9 <\/b><\/span><\/span><\/span>diretamente proporcional \u00e0 temperatura (energia t\u00e9rmica).<\/b><\/span><\/span><\/span><\/p>\n

32. Falsa \"\"<\/b><\/span><\/span><\/span> contraria o princ\u00edpio da a\u00e7\u00e3o e rea\u00e7\u00e3o de enunciado <\/b><\/span><\/span><\/span>\u201cQuando um corpo exerce uma for\u00e7a sobre outro, simultaneamente este outro reage sobre o primeiro aplicando-lhe uma for\u00e7a de <\/b><\/span><\/span><\/span>mesma intensidade,<\/b><\/span><\/span><\/span> mesma dire\u00e7\u00e3o, mas sentido contr\u00e1rio\u201d<\/b><\/span><\/span><\/span><\/p>\n

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

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

01- Falsa \"\"<\/b><\/span><\/span><\/span> Veja a <\/b><\/span><\/span><\/span>express\u00e3o matem\u00e1tica<\/b><\/span><\/span><\/span> da <\/b><\/span><\/span><\/span>acelera\u00e7\u00e3o da gravidade<\/b><\/span><\/span><\/span> de um planeta em locais <\/b><\/span><\/span><\/span>pr\u00f3ximos \u00e0 superf\u00edcie <\/b><\/span><\/span><\/span>do mesmo.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Terra \"\" <\/b><\/span><\/span><\/span>g<\/b><\/span><\/span><\/span>T<\/b><\/span><\/span><\/sub><\/span> = GM<\/b><\/span><\/span><\/span>T<\/b><\/span><\/span><\/sub><\/span>\/r<\/b><\/span><\/span><\/span>T<\/b><\/span><\/span><\/sub><\/span>2 <\/b><\/span><\/span><\/sup><\/span>(I).<\/b><\/span><\/span><\/span><\/p>\n

Marte \"\" <\/b><\/span><\/span><\/span>g<\/b><\/span><\/span><\/span>M<\/b><\/span><\/span><\/sub><\/span> = GM<\/b><\/span><\/span><\/span>M<\/b><\/span><\/span><\/sub><\/span>\/r<\/b><\/span><\/span><\/span>M<\/b><\/span><\/span><\/sub><\/span>2<\/b><\/span><\/span><\/sup><\/span> \"\" g<\/b><\/span><\/span><\/span>M<\/b><\/span><\/span><\/sub><\/span> = G.0,1.M<\/b><\/span><\/span><\/span>T<\/b><\/span><\/span><\/sub><\/span>\/(r<\/b><\/span><\/span><\/span>T<\/b><\/span><\/span><\/sub><\/span>\/2)<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sup><\/span> = G.0,1.M<\/b><\/span><\/span><\/span>T<\/b><\/span><\/span><\/sub><\/span>\/(r<\/b><\/span><\/span><\/span>T<\/b><\/span><\/span><\/sub><\/span>2<\/b><\/span><\/span><\/sup><\/span> <\/b>\/4) \"\" <\/b><\/span><\/span><\/span>g<\/b><\/span><\/span><\/span>M<\/b><\/span><\/span><\/sub><\/span> = 0,4GM<\/b><\/span><\/span><\/span>T<\/b><\/span><\/span><\/sub><\/span>\/r<\/b><\/span><\/span><\/span>T<\/b><\/span><\/span><\/sub><\/span>2<\/b><\/span><\/span><\/sup><\/span> (II).<\/b><\/span><\/span><\/span><\/p>\n

(I)\/(II) = g<\/b><\/span><\/span><\/span>T<\/b><\/span><\/span><\/sub><\/span>\/g<\/b><\/span><\/span><\/span>M<\/b><\/span><\/span><\/sub><\/span> = (GM<\/b><\/span><\/span><\/span>T<\/b><\/span><\/span><\/sub><\/span>\/r<\/b><\/span><\/span><\/span>T<\/b><\/span><\/span><\/sub><\/span>2<\/b><\/span><\/span><\/sup><\/span>)x(r<\/b><\/span><\/span><\/span>T<\/b><\/span><\/span><\/sub><\/span>2<\/b><\/span><\/span><\/sup><\/span>\/0,4GM<\/b><\/span><\/span><\/span>T<\/b><\/span><\/span><\/sub><\/span>) = 1\/0,4 \"\" g<\/b><\/span><\/span><\/span>M<\/b><\/span><\/span><\/sub><\/span> = 0,4g<\/b><\/span><\/span><\/span>T<\/b><\/span><\/span><\/sub><\/span> \"\" a <\/b><\/span><\/span><\/span>acelera\u00e7\u00e3o gravitacional de Marte \u00e9 40% <\/b><\/span><\/span><\/span>vezes <\/b><\/span><\/span><\/span>menor que a da Terra <\/b><\/span><\/span><\/span>e assim um <\/b><\/span><\/span><\/span>salto em Marte teria a altura e o alcance aproximado <\/b><\/span><\/span><\/span>de <\/b><\/span><\/span><\/span>um pouco mais da metade do que um salto na Terra<\/b><\/span><\/span><\/span>. Veja na figura que o <\/b><\/span><\/span><\/span>salto do personagem \u00e9 exagerado.<\/b><\/span><\/span><\/span><\/p>\n

02- Correta \"\"<\/b><\/span><\/span><\/span> <\/b>Veja 01.<\/b><\/span><\/span><\/span><\/p>\n

04- Falsa \"\" veja a seguir a equa\u00e7\u00e3o do movimento horizontal de um lan\u00e7amento obl\u00edquo.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

08. Correta \"\" <\/b><\/span><\/span><\/span>veja a demonstra\u00e7\u00e3o em <\/b><\/span><\/span><\/span>fisicaevestibular.com.br \u2013Mec\u00e3nica \u2013 Cinem\u00e1tica \u2013 Lan\u00e7amento obl\u00edquo – <\/b><\/span><\/span><\/span>Rela\u00e7\u00e3o entre o alcance\u00a0X, a velocidade inicial\u00a0V<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sub><\/span>\u00a0e o \u00e2ngulo de lan\u00e7amento\u00a0\u03b1.<\/b><\/span><\/span><\/span><\/p>\n

16. Falsa \"\" <\/b><\/span><\/span><\/span>Na <\/b><\/span><\/span><\/span>express\u00e3o da 3<\/b><\/span><\/span><\/span>a<\/b><\/span><\/span><\/sup><\/span> lei de Kepler<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>T<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sup><\/span>\/R<\/b><\/span><\/span><\/span>3<\/b><\/span><\/span><\/sup><\/span>\u00a0<\/b><\/span><\/span><\/span>= K\u2019,<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>observamos que \u00e0 medida que R<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>aumenta, T tamb\u00e9m aumenta,<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>o que significa que\u00a0<\/b><\/span><\/span><\/span>quanto mais afastado o planeta estiver do Sol maior ser\u00e1 seu ano <\/b><\/span><\/span><\/span>(tempo que demora para dar um volta completa ao redor do Sol).<\/b><\/span><\/span><\/span>Veja que esse per\u00edodo independe da acelera\u00e7\u00e3o da gravidade g.<\/b><\/span><\/span><\/span><\/p>\n

32. Falsa \"\" <\/b><\/span><\/span><\/span>pela express\u00e3o da <\/b><\/span><\/span><\/span>acelera\u00e7\u00e3o gravitacional de qualquer planeta g = g<\/b><\/span><\/span><\/span>T<\/b><\/span><\/span><\/sub><\/span> = GM\/r<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sup><\/span> voc\u00ea observa que <\/b><\/span><\/span><\/span>g independe da atmosfera do planeta, dependendo apenas de sua massa M e do raio r do planeta.<\/b><\/span><\/span><\/span><\/p>\n

R- (02+ 08) = 10<\/b><\/span><\/span><\/span><\/p>\n

03- <\/b><\/span><\/span><\/span>Lembre-se de que <\/b><\/span><\/span><\/span>quando o florete do esgrimista toca no advers\u00e1rio o circuito \u00e9 fechado acendendo sua l\u00e2mpada.<\/b><\/span><\/span><\/span><\/p>\n

01. Correta \"\"<\/b><\/span><\/span><\/span> <\/b><\/p>\n

\"\"<\/p>\n

02. Correta \"\"<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

04. Falsa \"\"<\/b><\/span><\/span><\/span> <\/b>fechando f<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span> ou f<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span> as duas l\u00e2mpadas acendem simultaneamente<\/b><\/span><\/span><\/span> (est\u00e3o em paralelo).<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

08. Falsa \"\"<\/b><\/span><\/span><\/span> <\/b>fechando f<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span> ou f<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span> as duas l\u00e2mpadas acendem simultaneamente <\/b><\/span><\/span><\/span>(est\u00e3o em s\u00e9rie).<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

16. e 32. Falsas \"\"<\/b><\/span><\/span><\/span> <\/b>fechando f<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span> ou f<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span> as duas l\u00e2mpadas acendem simultaneamente <\/b><\/span><\/span><\/span>(est\u00e3o em paralelo) <\/b><\/span><\/span><\/span>conforme a alternativa 04.<\/b><\/span><\/span><\/span><\/p>\n

64. Correta \"\"<\/b><\/span><\/span><\/span> <\/b><\/p>\n

\"\"<\/p>\n

R- (01 + 02 + 64) = 67<\/b><\/span><\/span><\/span><\/p>\n

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

01. Falsa \"\"<\/b><\/span><\/span><\/span> a <\/b><\/span><\/span><\/span>for\u00e7a m\u00e9dia de intera\u00e7\u00e3o m\u00e3o-bola obedece ao Princ\u00edpio da a\u00e7\u00e3o e rea\u00e7\u00e3o, <\/b><\/span><\/span><\/span>ou seja, tem sempre a <\/b><\/span><\/span><\/span>mesma intensidade,<\/b><\/span><\/span><\/span> mesma dire\u00e7\u00e3o, mas sentidos opostos.<\/b><\/span><\/span><\/span><\/p>\n

02. Falsa \"\"<\/b><\/span><\/span><\/span> Veja que est\u00e1 <\/b><\/span><\/span><\/span>sendo pedido o m\u00f3dulo da velocidade vertical (V<\/b><\/span><\/span><\/span>y<\/b><\/span><\/span><\/sub><\/span>) <\/b><\/span><\/span><\/span>da bola no <\/b><\/span><\/span><\/span>momento em que o jogador entra em contato novamente com ela, fornecido na \u00faltima figura.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

V<\/b><\/span><\/span><\/span>y<\/b><\/span><\/span><\/sub><\/span> = V.sen10<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sup><\/span> <\/b>= 20.0,17 (fornecido no formul\u00e1rio) <\/b><\/span><\/span><\/span>= 3,4 m\/s.<\/b><\/span><\/span><\/span><\/p>\n

04. Correta<\/b><\/span><\/span><\/span> \"\" Veja na <\/b><\/span><\/span><\/span>figura acima que o m\u00f3dulo da velocidade horizontal vale V<\/b><\/span><\/span><\/span>x<\/b><\/span><\/span><\/sub><\/span> = V.cos10<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sup><\/span> <\/b>= 20.0,98 (fornecida no formul\u00e1rio) \"\" <\/b><\/span><\/span><\/span>Vx = 19,6 m\/s.<\/b><\/span><\/span><\/span><\/p>\n

Teorema do impulso \"\"<\/b><\/span><\/span><\/span> <\/b>I = \u2206Q \"\" F.\u2206t = m.\u2206V \"\"<\/b><\/span><\/span><\/span> F.0,02 = 0,3.(19,6 \u2013 4) \"\" <\/b><\/span><\/span><\/span>F<\/b><\/span><\/span><\/span> = 4,68\/0,02 <\/b><\/span><\/span><\/span>= 234 N.<\/b><\/span><\/span><\/span><\/p>\n

08. Falsa \"\"<\/b><\/span><\/span><\/span> Se <\/b><\/span><\/span><\/span>existe movimento vertical, <\/b><\/span><\/span><\/span>a <\/b><\/span><\/span><\/span>intensidade da for\u00e7a m\u00e9dia vertical no contato m\u00e3o-bola n\u00e3o pode ser nula. <\/b><\/span><\/span><\/span><\/p>\n

16. Correta \"\"<\/b><\/span><\/span><\/span> Voc\u00ea pode <\/b><\/span><\/span><\/span>calcular <\/b><\/span><\/span><\/span>o <\/b><\/span><\/span><\/span>trabalho realizado <\/b><\/span><\/span><\/span>sobre a bola <\/b><\/span><\/span><\/span>durante a intera\u00e7\u00e3o <\/b><\/span><\/span><\/span>pelo <\/b><\/span><\/span><\/span>teorema da varia\u00e7\u00e3o da energia cin\u00e9tica \"\"<\/b><\/span><\/span><\/span> <\/b>W = E<\/b><\/span><\/span><\/span>cf<\/b><\/span><\/span><\/sub><\/span> \u2013 E<\/b><\/span><\/span><\/span>ci<\/b><\/span><\/span><\/sub><\/span> = m.V<\/b><\/span><\/span><\/span>f<\/b><\/span><\/span><\/sub><\/span>2<\/b><\/span><\/span><\/sup><\/span> \/2 \u2013 m.V<\/b><\/span><\/span><\/span>i<\/b><\/span><\/span><\/sub><\/span>2<\/b><\/span><\/span><\/sup><\/span> \/2 <\/b><\/span><\/span><\/span>= 0,3.\"\" – 0,3.\"\" \"\"<\/b><\/span><\/span><\/span><\/p>\n

W = 0,3×192,08 \u2013 0,3×8 = 57,624 \u2013 2,4 \"\" <\/b><\/span><\/span><\/span>W = 55,224 J<\/b><\/span><\/span><\/span><\/p>\n

R- (04 + 16) = 20<\/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 UFSC \u2013 SC- 2017 01- 01. Falsa Em todo lan\u00e7amento obl\u00edquo o\u00a0vetor velocidade\u00a0\u00a0\u00e9 sempre tangente \u00e0 trajet\u00f3ria em cada ponto e sempre decomposto em\u00a0e\u00a0. \u00a0 \u00a0Em\u00a0qualquer ponto \u00e9 v\u00e1lida a rela\u00e7\u00e3o V2\u00a0= Vx2\u00a0+ Vy2.\u00a0Observe que\u00a0no ponto mais alto da trajet\u00f3ria a velocidade vetorial\u00a0\u00a0n\u00e3o \u00e9 nula, tem intensidade m\u00ednima e \u00e9 igual \u00e0 componente<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":3104,"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-3106","page","type-page","status-publish","hentry"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/3106","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=3106"}],"version-history":[{"count":2,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/3106\/revisions"}],"predecessor-version":[{"id":3108,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/3106\/revisions\/3108"}],"up":[{"embeddable":true,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/3104"}],"wp:attachment":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/media?parent=3106"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}