{"id":2570,"date":"2016-10-26T03:51:54","date_gmt":"2016-10-26T03:51:54","guid":{"rendered":"http:\/\/fisicaevestibular.com.br\/novo\/?page_id=2570"},"modified":"2024-09-02T14:53:15","modified_gmt":"2024-09-02T14:53:15","slug":"dinamica-impulsiva","status":"publish","type":"page","link":"https:\/\/fisicaevestibular.com.br\/novo\/raciocinio-logico\/dinamica-impulsiva\/","title":{"rendered":"Din\u00e2mica Impulsiva"},"content":{"rendered":"

DIN\u00c2MICA IMPULSIVA<\/b><\/span><\/span><\/span><\/p>\n

Esse conte\u00fado envolve muita teoria, em caso de d\u00favidas voc\u00ea pode encontr\u00e1-la em:<\/b><\/span><\/span><\/span> <\/b><\/p>\n

fisicaevestibular.com.br \"\" Mec\u00e2nica \"\" Impulso e Quantidade de Movimento \"\" Conserva\u00e7\u00e3o da Quantidade de Movimento \"\" Colis\u00f5es Mec\u00e2nicas.<\/b><\/span><\/span><\/span><\/p>\n

Exerc\u00edcios de Vestibulares com resolu\u00e7\u00f5es comentadas sobre <\/b><\/span><\/span><\/span><\/p>\n

Din\u00e2mica Impulsiva<\/b><\/span><\/span><\/span><\/p>\n

01-(ITA-SP)<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>Um <\/b><\/span><\/span><\/span>autom\u00f3vel para <\/b><\/span><\/span><\/span>quase que <\/b><\/span><\/span><\/span>instantaneamente ao bater frontalmente numa \u00e1rvore.<\/b><\/span><\/span><\/span> <\/b><\/p>\n

A <\/b><\/span><\/span><\/span>prote\u00e7\u00e3o oferecida pelo “air-bag”, <\/b><\/span><\/span><\/span>comparativamente <\/b><\/span><\/span><\/span>ao carro que dele n\u00e3o disp\u00f5e, adv\u00e9m<\/b><\/span><\/span><\/span> do fato de que a <\/b><\/span><\/span><\/span>transfer\u00eancia para o carro de parte do momentum do motorista se d\u00e1 em condi\u00e7\u00e3o <\/b><\/span><\/span><\/span>de<\/b><\/span><\/span><\/span><\/p>\n

a) menor for\u00e7a <\/b><\/span><\/span><\/span>em <\/b><\/span><\/span><\/span>maior per\u00edodo de tempo.\u00a0\u00a0\u00a0\u00a0\u00a0 <\/b><\/span><\/span><\/span><\/p>\n

b) menor velocidade, <\/b><\/span><\/span><\/span>com <\/b><\/span><\/span><\/span>mesma acelera\u00e7\u00e3o.\u00a0\u00a0\u00a0\u00a0\u00a0 <\/b><\/span><\/span><\/span><\/p>\n

c) menor energia, <\/b><\/span><\/span><\/span>numa<\/b><\/span><\/span><\/span> dist\u00e2ncia menor.\u00a0\u00a0\u00a0\u00a0\u00a0 <\/b><\/span><\/span><\/span><\/p>\n

d) menor velocidade<\/b><\/span><\/span><\/span> e <\/b><\/span><\/span><\/span>maior desacelera\u00e7\u00e3o.\u00a0\u00a0\u00a0\u00a0\u00a0 <\/b><\/span><\/span><\/span><\/p>\n

e) mesmo tempo<\/b><\/span><\/span><\/span>, com <\/b><\/span><\/span><\/span>for\u00e7a menor.<\/b><\/span><\/span><\/span><\/p>\n

02-(FGV-SP)<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>Em <\/b><\/span><\/span><\/span>plena feira, <\/b><\/span><\/span><\/span>enfurecida com a cantada que havia recebido, a <\/b><\/span><\/span><\/span>mocinha, armada com um tomate de 120 g, lan\u00e7a-o em dire\u00e7\u00e3o ao atrevido feirante, atingindo-lhe a cabe\u00e7a com velocidade de 6 m\/s.<\/b><\/span><\/span><\/span>\"\"<\/p>\n

Se o <\/b><\/span><\/span><\/span>choque do tomate foi perfeitamente inel\u00e1stico <\/b><\/span><\/span><\/span>e a <\/b><\/span><\/span><\/span>intera\u00e7\u00e3o trocada pelo tomate<\/b><\/span><\/span><\/span> e a <\/b><\/span><\/span><\/span>cabe\u00e7a do rapaz demorou 0,01 s<\/b><\/span><\/span><\/span>, a <\/b><\/span><\/span><\/span>intensidade da for\u00e7a m\u00e9dia associada \u00e0 intera\u00e7\u00e3o <\/b><\/span><\/span><\/span>foi de<\/b><\/span><\/span><\/span><\/p>\n

a) <\/b><\/span><\/span><\/span>20 N.\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/b><\/span><\/span><\/span><\/p>\n

b) <\/b><\/span><\/span><\/span>36 N.\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/b><\/span><\/span><\/span><\/p>\n

c) <\/b><\/span><\/span><\/span>48 N.\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/b><\/span><\/span><\/span><\/p>\n

d) <\/b><\/span><\/span><\/span>72 N.\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/b><\/span><\/span><\/span><\/p>\n

e) <\/b><\/span><\/span><\/span>94 N.<\/b><\/span><\/span><\/span><\/p>\n

03-(FUVEST-SP)<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Um <\/b><\/span><\/span><\/span>avi\u00e3o a jato voa a \u00a0900km\/h. <\/b><\/span><\/span><\/span>Um <\/b><\/span><\/span><\/span>p\u00e1ssaro de 2,0 kg<\/b><\/span><\/span><\/span> \u00e9 <\/b><\/span><\/span><\/span>apanhado<\/b><\/span><\/span><\/span> por ele, <\/b><\/span><\/span><\/span>chocando-se perpendicularmente com o vidro dianteiro inquebr\u00e1vel da cabina.<\/b><\/span><\/span><\/span><\/p>\n

Que <\/b><\/span><\/span><\/span>for\u00e7a \u00e9 aplicada no vidro, se o choque dura um mil\u00e9simo de segundo?<\/b><\/span><\/span><\/span><\/p>\n

04-(Ufla-MG)<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>Em uma <\/b><\/span><\/span><\/span>partida de t\u00eanis <\/b><\/span><\/span><\/span>o <\/b><\/span><\/span><\/span>jogador recebe a bola<\/b><\/span><\/span><\/span> com <\/b><\/span><\/span><\/span>componente horizontal <\/b><\/span><\/span><\/span>de <\/b><\/span><\/span><\/span>velocidade V<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>\u00a0e a rebate com componente horizontal de velocidade 3V<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>, em sentido contr\u00e1rio. <\/b><\/span><\/span><\/span>Considere <\/b><\/span><\/span><\/span>g = 10 m\/s<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sup><\/span>. \u00a0<\/b><\/span><\/span><\/span><\/p>\n

Supondo que a <\/b><\/span><\/span><\/span>for\u00e7a aplicada na colis\u00e3o da bola com a raquete seja 60 vezes o peso da bola e atue durante 0,2s, <\/b><\/span><\/span><\/span>a <\/b><\/span><\/span><\/span>velocidade inicial da bola<\/b><\/span><\/span><\/span>, em <\/b><\/span><\/span><\/span>m\u00f3dulo, <\/b><\/span><\/span><\/span>\u00e9 de:<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

05-(UnB-DF)<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>Aprende-se em <\/b><\/span><\/span><\/span>aulas de educa\u00e7\u00e3o f\u00edsica <\/b><\/span><\/span><\/span>que, ao <\/b><\/span><\/span><\/span>se saltar, <\/b><\/span><\/span><\/span>\u00e9 <\/b><\/span><\/span><\/span>fundamental flexionar <\/b><\/span><\/span><\/span>as pernas para <\/b><\/span><\/span><\/span>amenizar o impacto no solo e evitar danos \u00e0 coluna vertebral,<\/b><\/span><\/span><\/span> que <\/b><\/span><\/span><\/span>possui certo grau <\/b><\/span><\/span><\/span>de <\/b><\/span><\/span><\/span>flexibilidade. <\/b><\/span><\/span><\/span><\/p>\n

No <\/b><\/span><\/span><\/span>caso de uma queda em p\u00e9, <\/b><\/span><\/span><\/span>com as <\/b><\/span><\/span><\/span>pernas esticadas,<\/b><\/span><\/span><\/span> uma <\/b><\/span><\/span><\/span>pessoa pode chegar a ter, <\/b><\/span><\/span><\/span>no estado de <\/b><\/span><\/span><\/span>maior compress\u00e3o da coluna, a sua altura diminu\u00edda em at\u00e9 3 cm. <\/b><\/span><\/span><\/span><\/p>\n

Nesse caso, o <\/b><\/span><\/span><\/span>esqueleto da pessoa, <\/b><\/span><\/span><\/span>com a <\/b><\/span><\/span><\/span>velocidade adquirida durante a queda, desacelera bruscamente no espa\u00e7o m\u00e1ximo de 3 cm.<\/b><\/span><\/span><\/span><\/p>\n

Supondo que uma <\/b><\/span><\/span><\/span>pessoa de 70 kg caia de um degrau de 0,5 m de altura, atingindo o solo em p\u00e9, <\/b><\/span><\/span><\/span>com as <\/b><\/span><\/span><\/span>pernas esticadas e recebendo todo o impacto diretamente sobre <\/b><\/span><\/span><\/span>o <\/b><\/span><\/span><\/span>calcanhar e a coluna, julgue os itens seguintes <\/b><\/span><\/span><\/span>(g = 10 m\/s<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sup><\/span>).<\/b><\/span><\/span><\/span><\/p>\n

(1) <\/b><\/span><\/span><\/span>No <\/b><\/span><\/span><\/span>instante em que a pessoa deixa o degrau, <\/b><\/span><\/span><\/span>a <\/b><\/span><\/span><\/span>varia\u00e7\u00e3o do seu momento linear <\/b><\/span><\/span><\/span>\u00e9 produzida pela <\/b><\/span><\/span><\/span>for\u00e7a peso.<\/b><\/span><\/span><\/span><\/p>\n

(2) Durante o impacto, <\/b><\/span><\/span><\/span>a <\/b><\/span><\/span><\/span>for\u00e7a de compress\u00e3o m\u00e9dia<\/b><\/span><\/span><\/span> a que a <\/b><\/span><\/span><\/span>coluna est\u00e1 sujeita <\/b><\/span><\/span><\/span>\u00e9 <\/b><\/span><\/span><\/span>momentaneamente<\/b><\/span><\/span><\/span> <\/b>superior ao peso correspondente \u00e0 massa de 1 tonelada.<\/b><\/span><\/span><\/span><\/p>\n

(3) <\/b><\/span><\/span><\/span>Em <\/b><\/span><\/span><\/span>m\u00f3dulo,<\/b><\/span><\/span><\/span> a <\/b><\/span><\/span><\/span>for\u00e7a de compress\u00e3o da coluna \u00e9 igual \u00e0 for\u00e7a que o solo exerce nos p\u00e9s da pessoa.<\/b><\/span><\/span><\/span><\/p>\n

(4) <\/b><\/span><\/span><\/span>Se <\/b><\/span><\/span><\/span>flexionasse as pernas, <\/b><\/span><\/span><\/span>a pessoa <\/b><\/span><\/span><\/span>aumentaria o espa\u00e7o de desacelera\u00e7\u00e3o, diminuindo<\/b><\/span><\/span><\/span>, portanto, o <\/b><\/span><\/span><\/span>impacto do choque com o solo.<\/b><\/span><\/span><\/span><\/p>\n

06-(UDESC-SC)<\/b><\/span><\/span><\/span>\u00a0 <\/b><\/span><\/span><\/span>No dia 25 de julho o brasileiro <\/b><\/span><\/span><\/span>Felipe Massa, <\/b><\/span><\/span><\/span>piloto da <\/b><\/span><\/span><\/span>equipe Ferrari, <\/b><\/span><\/span><\/span>sofreu um <\/b><\/span><\/span><\/span>grave acidente <\/b><\/span><\/span><\/span>na segunda parte do treino oficial para o Grande Pr\u00eamio da Hungria de F\u00f3rmula 1.<\/b><\/span><\/span><\/span><\/p>\n

O <\/b><\/span><\/span><\/span>piloto sofreu um corte de oito cent\u00edmetros <\/b><\/span><\/span><\/span>na altura do superc\u00edlio esquerdo <\/b><\/span><\/span><\/span>ap\u00f3s o choque de uma mola que se soltou do carro de Rubens Barrichello <\/b><\/span><\/span><\/span>contra seu capacete.<\/b><\/span><\/span><\/span><\/p>\n

O <\/b><\/span><\/span><\/span>carro de Felipe Massa estava a 280,8 km\/h,<\/b><\/span><\/span><\/span> a <\/b><\/span><\/span><\/span>massa da mola era 0,8 kg <\/b><\/span><\/span><\/span>e o <\/b><\/span><\/span><\/span>tempo<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

estimado do impacto foi 0,026s.<\/b><\/span><\/span><\/span> <\/b><\/p>\n

Supondo que o <\/b><\/span><\/span><\/span>choque tenha ocorrido na horizontal,<\/b><\/span><\/span><\/span> que a <\/b><\/span><\/span><\/span>velocidade inicial da mola tenha sido 93,6 km\/h <\/b><\/span><\/span><\/span>(na mesma dire\u00e7\u00e3o e sentido da velocidade do carro) e a <\/b><\/span><\/span><\/span>velocidade final 0,0 km\/h, <\/b><\/span><\/span><\/span>a <\/b><\/span><\/span><\/span>for\u00e7a m\u00e9dia exercida sobre o capacete <\/b><\/span><\/span><\/span>foi:<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

07- (UEM)<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>Um <\/b><\/span><\/span><\/span>vag\u00e3o, <\/b><\/span><\/span><\/span>deslocando-se <\/b><\/span><\/span><\/span>para a direita com uma velocidade de 10 m\/s, <\/b><\/span><\/span><\/span>\u00e9 <\/b><\/span><\/span><\/span>fragmentado<\/b><\/span><\/span><\/span> por uma <\/b><\/span><\/span><\/span>explos\u00e3o, em dois peda\u00e7os (1) e (2) de massas iguais, <\/b><\/span><\/span><\/span>conforme mostra a <\/b><\/span><\/span><\/span>figura.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\u00a0Sejam\"\"<\/b><\/span><\/span><\/span>\u00a0e\u00a0\"\"\u201a as velocidades respectivas dos dois fragmentos<\/b><\/span><\/span><\/span> logo <\/b><\/span><\/span><\/span>ap\u00f3s a explos\u00e3o <\/b><\/span><\/span><\/span>e considerando que\u00a0\"\"\u00a0e\u00a0\"\"\u201a possuem <\/b><\/span><\/span><\/span>a mesma dire\u00e7\u00e3o do movimento inicial, assinale,<\/b><\/span><\/span><\/span> dentre as <\/b><\/span><\/span><\/span>alternativas a seguir, <\/b><\/span><\/span><\/span>aquela(s) que <\/b><\/span><\/span><\/span>poderia(m) corresponder ao(s) movimento(s) de (1) e (2) depois da explos\u00e3o. Anote<\/b><\/span><\/span><\/span> a <\/b><\/span><\/span><\/span>soma <\/b><\/span><\/span><\/span>das <\/b><\/span><\/span><\/span>verdadeiras:<\/b><\/span><\/span><\/span><\/p>\n

(01) v<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>\u00a0= 15 m\/s <\/b><\/span><\/span><\/span>para a <\/b><\/span><\/span><\/span>direita<\/b><\/span><\/span><\/span> e <\/b><\/span><\/span><\/span>v<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>\u00a0= 5 m\/s <\/b><\/span><\/span><\/span>para a <\/b><\/span><\/span><\/span>esquerda.<\/b><\/span><\/span><\/span>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/b><\/span><\/span><\/span><\/p>\n

(02) v<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>\u00a0= 20 m\/s <\/b><\/span><\/span><\/span>para a <\/b><\/span><\/span><\/span>direita<\/b><\/span><\/span><\/span> e <\/b><\/span><\/span><\/span>v<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>\u00a0= 0.<\/b><\/span><\/span><\/span><\/p>\n

(04) v<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>\u00a0= 30 m\/s <\/b><\/span><\/span><\/span>para a <\/b><\/span><\/span><\/span>direita <\/b><\/span><\/span><\/span>e <\/b><\/span><\/span><\/span>v<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>\u00a0= 10 m\/s <\/b><\/span><\/span><\/span>para a <\/b><\/span><\/span><\/span>esquerda.<\/b><\/span><\/span><\/span>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/b><\/span><\/span><\/span><\/p>\n

(08) v<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>\u00a0= 25 m\/s <\/b><\/span><\/span><\/span>para a <\/b><\/span><\/span><\/span>direita<\/b><\/span><\/span><\/span> e <\/b><\/span><\/span><\/span>v<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>\u00a0= 0.<\/b><\/span><\/span><\/span><\/p>\n

(16) v<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>\u00a0= 25 m\/s <\/b><\/span><\/span><\/span>para a <\/b><\/span><\/span><\/span>direita<\/b><\/span><\/span><\/span> e <\/b><\/span><\/span><\/span>v<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>\u00a0= 5 m\/s <\/b><\/span><\/span><\/span>para a <\/b><\/span><\/span><\/span>esquerda.<\/b><\/span><\/span><\/span>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/b><\/span><\/span><\/span><\/p>\n

(32) v<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>\u00a0= 10 m\/<\/b><\/span><\/span><\/span>s para a <\/b><\/span><\/span><\/span>direita <\/b><\/span><\/span><\/span>e <\/b><\/span><\/span><\/span>v<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>\u00a0= 0.<\/b><\/span><\/span><\/span><\/p>\n

(64) v<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>\u00a0= 50 m\/s <\/b><\/span><\/span><\/span>para a <\/b><\/span><\/span><\/span>direita<\/b><\/span><\/span><\/span> e <\/b><\/span><\/span><\/span>v<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>\u00a0= 30 m\/s<\/b><\/span><\/span><\/span> para a <\/b><\/span><\/span><\/span>esquerda.<\/b><\/span><\/span><\/span><\/p>\n

08-(Ufrj-RJ)<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>A <\/b><\/span><\/span><\/span>figura representa, <\/b><\/span><\/span><\/span>uma <\/b><\/span><\/span><\/span>jangada de comprimento L, <\/b><\/span><\/span><\/span>em <\/b><\/span><\/span><\/span>repouso, flutuando<\/b><\/span><\/span><\/span> em alto mar com o <\/b><\/span><\/span><\/span>pescador de p\u00e9, equidistante das extremidades. <\/b><\/span><\/span><\/span>\"\"<\/p>\n

Por <\/b><\/span><\/span><\/span>inadvert\u00eancia, <\/b><\/span><\/span><\/span>ele havia levado a jangada para um <\/b><\/span><\/span><\/span>local <\/b><\/span><\/span><\/span>onde a <\/b><\/span><\/span><\/span>Marinha de Guerra <\/b><\/span><\/span><\/span>estava realizando <\/b><\/span><\/span><\/span>exerc\u00edcios de tiro. <\/b><\/span><\/span><\/span><\/p>\n

Assim, em <\/b><\/span><\/span><\/span>determinado instante, <\/b><\/span><\/span><\/span>ele <\/b><\/span><\/span><\/span>percebe um torpedo que se desloca numa dire\u00e7\u00e3o perpendicular <\/b><\/span><\/span><\/span>\u00e0 do <\/b><\/span><\/span><\/span>comprimento da jangada e que ir\u00e1 atingi-la muito pr\u00f3ximo de uma de suas extremidades.<\/b><\/span><\/span><\/span><\/p>\n

Para <\/b><\/span><\/span><\/span>tentar evitar que a jangada seja atingida, <\/b><\/span><\/span><\/span>o <\/b><\/span><\/span><\/span>pescador deve correr ao longo da dire\u00e7\u00e3o AB, aproximando-se de A ou de B? Justifique sua resposta.<\/b><\/span><\/span><\/span><\/p>\n

09-(FUVEST-SP)<\/b><\/span><\/span><\/span>\u00a0 <\/b><\/span><\/span><\/span>A <\/b><\/span><\/span><\/span>part\u00edcula neutra <\/b><\/span><\/span><\/span>conhecida como <\/b><\/span><\/span><\/span>m\u00e9son K<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sub><\/span>\u00a0\u00e9 inst\u00e1vel e decai, <\/b><\/span><\/span><\/span>emitindo <\/b><\/span><\/span><\/span>duas part\u00edculas, com massas iguais, <\/b><\/span><\/span><\/span>uma <\/b><\/span><\/span><\/span>positiva e outra negativa, chamadas, respectivamente<\/b><\/span><\/span><\/span>, <\/b><\/span><\/span><\/span>m\u00e9son \"\"\u00a0\u00a0e m\u00e9son\u00a0\"\".<\/b><\/span><\/span><\/span> <\/b>\"\"<\/p>\n

Em um <\/b><\/span><\/span><\/span>experimento, foi observado o<\/b><\/span><\/span><\/span> <\/b>decaimento de um K<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sub><\/span>, em repouso, com emiss\u00e3o do par \"\"\u00a0\u00a0<\/b><\/span><\/span><\/span>e\u00a0\"\"<\/b><\/span><\/span><\/span>.<\/b><\/span><\/span><\/span><\/p>\n

Das <\/b><\/span><\/span><\/span>figuras a seguir,<\/b><\/span><\/span><\/span> qual <\/b><\/span><\/span><\/span>poderia representar as dire\u00e7\u00f5es e sentidos das velocidades das part\u00edculas\u00a0\u00a0e\u00a0no sistema de refer\u00eancia em que o K<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sub><\/span>\u00a0estava em repouso?<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

10-(UNICAMP-SP)<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Uma <\/b><\/span><\/span><\/span>bomba explode em tr\u00eas fragmentos <\/b><\/span><\/span><\/span>na <\/b><\/span><\/span><\/span>forma mostrada na figura.<\/b><\/span><\/span><\/span><\/p>\n

a) Ache v<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>\u00a0<\/b><\/span><\/span><\/span>em <\/b><\/span><\/span><\/span>termos de v<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sub><\/span>.\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/b><\/span><\/span><\/span><\/p>\n

b) Ache v<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>\u00a0<\/b><\/span><\/span><\/span>em <\/b><\/span><\/span><\/span>termos de v<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sub><\/span>.\u00a0\u00a0 <\/b><\/span><\/span><\/span><\/p>\n

c) <\/b><\/span><\/span><\/span>A <\/b><\/span><\/span><\/span>energia mec\u00e2nica aumenta, diminui ou permanece a mesma? Justifique.<\/b><\/span><\/span><\/span><\/p>\n

11-(UNIFESP-SP)<\/b><\/span><\/span><\/span>\u00a0Completamente lotado, <\/b><\/span><\/span><\/span>certo <\/b><\/span><\/span><\/span>\u00f4nibus trafega a uma velocidade de 10 m\/s.<\/b><\/span><\/span><\/span> <\/b><\/p>\n

Um <\/b><\/span><\/span><\/span>rapaz <\/b><\/span><\/span><\/span>\u00e0 beira da estrada brinca com uma <\/b><\/span><\/span><\/span>bola de t\u00eanis. <\/b><\/span><\/span><\/span><\/p>\n

Quando o <\/b><\/span><\/span><\/span>\u00f4nibus passa, <\/b><\/span><\/span><\/span>ele <\/b><\/span><\/span><\/span>resolve jogar a bola na traseira do mesmo.<\/b><\/span><\/span><\/span> <\/b><\/p>\n

Sabendo-se que a <\/b><\/span><\/span><\/span>bola atinge a traseira do \u00f4nibus perpendicularmente, <\/b><\/span><\/span><\/span>com <\/b><\/span><\/span><\/span>velocidade de 20 m\/s, <\/b><\/span><\/span><\/span>em <\/b><\/span><\/span><\/span>rela\u00e7\u00e3o ao solo,<\/b><\/span><\/span><\/span> qual a <\/b><\/span><\/span><\/span>velocidade horizontal final da bola ap\u00f3s o choque?<\/b><\/span><\/span><\/span><\/p>\n

Considere o <\/b><\/span><\/span><\/span>choque perfeitamente el\u00e1stico.<\/b><\/span><\/span><\/span><\/p>\n

12-(UNICAMP-SP)<\/b><\/span><\/span><\/span>\u00a0Um <\/b><\/span><\/span><\/span>objeto<\/b><\/span><\/span><\/span> de <\/b><\/span><\/span><\/span>massa m<\/b><\/span><\/span><\/span>1 <\/b><\/span><\/span><\/sub><\/span>= 4,0kg <\/b><\/span><\/span><\/span>e <\/b><\/span><\/span><\/span>velocidade V<\/b><\/span><\/span><\/span>1 <\/b><\/span><\/span><\/sub><\/span>= 3,0 m\/s choca-se <\/b><\/span><\/span><\/span>com <\/b><\/span><\/span><\/span>outro objeto<\/b><\/span><\/span><\/span> em <\/b><\/span><\/span><\/span>repouso, de massa m<\/b><\/span><\/span><\/span>2 <\/b><\/span><\/span><\/sub><\/span>= 2,0 kg. <\/b><\/span><\/span><\/span><\/p>\n

A <\/b><\/span><\/span><\/span>colis\u00e3o ocorre de maneira que a perda de energia cin\u00e9tica \u00e9 m\u00e1xima, <\/b><\/span><\/span><\/span>mas <\/b><\/span><\/span><\/span>consistente<\/b><\/span><\/span><\/span>\u00a0 com o <\/b><\/span><\/span><\/span>Princ\u00edpio de Conserva\u00e7\u00e3o da Quantidade de Movimento.<\/b><\/span><\/span><\/span><\/p>\n

a) <\/b><\/span><\/span><\/span>Quais as <\/b><\/span><\/span><\/span>velocidades dos objetos imediatamente ap\u00f3s a colis\u00e3o?<\/b><\/span><\/span><\/span><\/p>\n

b) <\/b><\/span><\/span><\/span>Qual a <\/b><\/span><\/span><\/span>varia\u00e7\u00e3o de energia cin\u00e9tica do sistema?<\/b><\/span><\/span><\/span><\/p>\n

13-(UFBA)<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>No dia 4 de julho de 2005, coincidindo com as comemora\u00e7\u00f5es da independ\u00eancia dos Estados Unidos da Am\u00e9rica, os <\/b><\/span><\/span><\/span>meios de comunica\u00e7\u00e3o <\/b><\/span><\/span><\/span>de todo o mundo <\/b><\/span><\/span><\/span>divulgaram o impacto <\/b><\/span><\/span><\/span>de uma <\/b><\/span><\/span><\/span>pequena nave, n\u00e3o tripulada, com o cometa Tempel 1. <\/b><\/span><\/span><\/span><\/p>\n

Uma <\/b><\/span><\/span><\/span>anima\u00e7\u00e3o<\/b><\/span><\/span><\/span> do evento foi <\/b><\/span><\/span><\/span>distribu\u00edda \u00e0s emissoras de televis\u00e3o<\/b><\/span><\/span><\/span> e <\/b><\/span><\/span><\/span>disponibilizada na rede de computadores. <\/b><\/span><\/span><\/span><\/p>\n

Alguns <\/b><\/span><\/span><\/span>instant\u00e2neos dessa anima\u00e7\u00e3o <\/b><\/span><\/span><\/span>– apresentados nas <\/b><\/span><\/span><\/span>figuras I, II e III <\/b><\/span><\/span><\/span>– mostram <\/b><\/span><\/span><\/span>respectivamente a nave ao encaminhar-se para o cometa, o instante da colis\u00e3o e a cratera formada.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

No <\/b><\/span><\/span><\/span>dia seguinte, <\/b><\/span><\/span><\/span>a <\/b><\/span><\/span><\/span>imprensa internacional <\/b><\/span><\/span><\/span>tamb\u00e9m <\/b><\/span><\/span><\/span>divulgou que uma astr\u00f3loga russa <\/b><\/span><\/span><\/span>entrou com uma <\/b><\/span><\/span><\/span>a\u00e7\u00e3o indenizat\u00f3ria na Justi\u00e7a americana por perdas e danos.<\/b><\/span><\/span><\/span> <\/b><\/p>\n

Alegava a referida senhora que a <\/b><\/span><\/span><\/span>a\u00e7\u00e3o americana prejudicou a confiabilidade de seus mapas astrais, <\/b><\/span><\/span><\/span>no momento em que <\/b><\/span><\/span><\/span>modificou as condi\u00e7\u00f5es de movimento de um corpo celeste.<\/b><\/span><\/span><\/span><\/p>\n

Considere <\/b><\/span><\/span><\/span>as informa\u00e7\u00f5es:<\/b><\/span><\/span><\/span><\/p>\n

– o <\/b><\/span><\/span><\/span>choque<\/b><\/span><\/span><\/span> foi frontal e <\/b><\/span><\/span><\/span>completamente inel\u00e1stico;<\/b><\/span><\/span><\/span><\/p>\n

– o <\/b><\/span><\/span><\/span>cometa,<\/b><\/span><\/span><\/span> no <\/b><\/span><\/span><\/span>referencial da nave, movia-se<\/b><\/span><\/span><\/span> em <\/b><\/span><\/span><\/span>sua dire\u00e7\u00e3o com velocidade v(cometa) = 10 km\/s;<\/b><\/span><\/span><\/span><\/p>\n

– o <\/b><\/span><\/span><\/span>cometa,<\/b><\/span><\/span><\/span> em forma de um <\/b><\/span><\/span><\/span>paralelep\u00edpedo de dimens\u00f5es 5km \u00d7 5km \u00d7 10km, tem densidade <\/b><\/span><\/span><\/span>aproximadamente <\/b><\/span><\/span><\/span>igual \u00e0 densidade da \u00e1gua, d<\/b><\/span><\/span><\/span>\u00e1gua<\/b><\/span><\/span><\/sub><\/span> = 1kg\/litro;<\/b><\/span><\/span><\/span><\/p>\n

– a <\/b><\/span><\/span><\/span>nave, com massa igual a 100 kg, n\u00e3o transportava explosivos.<\/b><\/span><\/span><\/span><\/p>\n

Calcule a modifica\u00e7\u00e3o na velocidade do cometa <\/b><\/span><\/span><\/span>e fa\u00e7a um coment\u00e1rio <\/b><\/span><\/span><\/span>sobre a alega\u00e7\u00e3o da astr\u00f3loga russa.<\/b><\/span><\/span><\/span><\/p>\n

14-(IME-RJ)<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

O <\/b><\/span><\/span><\/span>carro A foi abalroado pelo caminh\u00e3o B <\/b><\/span><\/span><\/span>de <\/b><\/span><\/span><\/span>massa igual ao triplo da massa do carro.<\/b><\/span><\/span><\/span> <\/b><\/p>\n

O <\/b><\/span><\/span><\/span>caminh\u00e3o<\/b><\/span><\/span><\/span> desloca-se com <\/b><\/span><\/span><\/span>velocidade de 36 km\/h.<\/b><\/span><\/span><\/span> <\/b><\/p>\n

Ap\u00f3s o choque, <\/b><\/span><\/span><\/span>que se deu no <\/b><\/span><\/span><\/span>ponto P,<\/b><\/span><\/span><\/span> os <\/b><\/span><\/span><\/span>dois ve\u00edculos, unidos, deslocaram-se em linha reta at\u00e9 o ponto Q. <\/b><\/span><\/span><\/span><\/p>\n

O <\/b><\/span><\/span><\/span>motorista do carro<\/b><\/span><\/span><\/span> declarou que sua <\/b><\/span><\/span><\/span>velocidade no instante do choque era inferior \u00e0 m\u00e1xima permitida, que \u00e9 de 80 km\/h.<\/b><\/span><\/span><\/span><\/p>\n

Diga, <\/b><\/span><\/span><\/span>justificando, se essa declara\u00e7\u00e3o \u00e9 falsa ou verdadeira.<\/b><\/span><\/span><\/span><\/p>\n

15-(EFB)<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>Dois <\/b><\/span><\/span><\/span>m\u00f3veis M e N <\/b><\/span><\/span><\/span>movendo-se em <\/b><\/span><\/span><\/span>sentidos opostos com velocidades de 5m\/s e 3m\/s <\/b><\/span><\/span><\/span>respectivamente, sofrem uma <\/b><\/span><\/span><\/span>colis\u00e3o unidimensional, parcialmente el\u00e1stica de coeficiente de restitui\u00e7\u00e3o e = 3\/4. <\/b><\/span><\/span><\/span><\/p>\n

Suas <\/b><\/span><\/span><\/span>massas s\u00e3o m<\/b><\/span><\/span><\/span>M <\/b><\/span><\/span><\/sub><\/span>= 15 kg e m<\/b><\/span><\/span><\/span>N <\/b><\/span><\/span><\/sub><\/span>= 13 kg. <\/b><\/span><\/span><\/span>Determine a <\/b><\/span><\/span><\/span>intensidade e o sentido de suas velocidades ap\u00f3s o choque.<\/b><\/span><\/span><\/span><\/p>\n

16-(Ufrj-RJ)<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>\"\"<\/p>\n

A <\/b><\/span><\/span><\/span>figura representa o gr\u00e1fico velocidade-tempo <\/b><\/span><\/span><\/span>de uma <\/b><\/span><\/span><\/span>colis\u00e3o unidimensional <\/b><\/span><\/span><\/span>entre dois <\/b><\/span><\/span><\/span>carrinhos\u00a0 A e B.<\/b><\/span><\/span><\/span><\/p>\n

<\/a> a) <\/b><\/span><\/span><\/span>Qual \u00e9 o <\/b><\/span><\/span><\/span>m\u00f3dulo da raz\u00e3o entre a for\u00e7a m\u00e9dia que o carrinho A exerce sobre o carrinho B <\/b><\/span><\/span><\/span>e a <\/b><\/span><\/span><\/span>for\u00e7a m\u00e9dia que o carrinho B exerce sobre o carrinho A? Justifique sua resposta.<\/b><\/span><\/span><\/span><\/p>\n

b) <\/b><\/span><\/span><\/span>Calcule a <\/b><\/span><\/span><\/span>raz\u00e3o entre as massa m<\/b><\/span><\/span><\/span>A<\/b><\/span><\/span><\/sub><\/span>\u00a0e m<\/b><\/span><\/span><\/span>B<\/b><\/span><\/span><\/sub><\/span>\u00a0<\/b><\/span><\/span><\/span>dos carrinhos<\/b><\/span><\/span><\/span><\/p>\n

17-(FUVEST-SP)<\/b><\/span><\/span><\/span><\/p>\n

Em uma <\/b><\/span><\/span><\/span>canaleta circular, plana e horizontal, <\/b><\/span><\/span><\/span>podem <\/b><\/span><\/span><\/span>deslizar duas pequenas bolas A e B, <\/b><\/span><\/span><\/span>com <\/b><\/span><\/span><\/span>massas M<\/b><\/span><\/span><\/span>A<\/b><\/span><\/span><\/sub><\/span>\u00a0= 3 M<\/b><\/span><\/span><\/span>B<\/b><\/span><\/span><\/sub><\/span>, <\/b><\/span><\/span><\/span>que s\u00e3o <\/b><\/span><\/span><\/span>lan\u00e7adas uma contra a outra, <\/b><\/span><\/span><\/span>com <\/b><\/span><\/span><\/span>igual velocidade V<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sub><\/span>, <\/b><\/span><\/span><\/span>a <\/b><\/span><\/span><\/span>partir <\/b><\/span><\/span><\/span>das <\/b><\/span><\/span><\/span>posi\u00e7\u00f5es indicadas. <\/b><\/span><\/span><\/span>\"\"<\/p>\n

Ap\u00f3s o <\/b><\/span><\/span><\/span>primeiro choque entre elas (em 1), que n\u00e3o \u00e9 el\u00e1stico,<\/b><\/span><\/span><\/span> as <\/b><\/span><\/span><\/span>duas passam a movimentar-se<\/b><\/span><\/span><\/span> no <\/b><\/span><\/span><\/span>sentido hor\u00e1rio, <\/b><\/span><\/span><\/span>sendo que a <\/b><\/span><\/span><\/span>bola B mant\u00e9m o m\u00f3dulo de sua velocidade V<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sub><\/span>. <\/b><\/span><\/span><\/span><\/p>\n

Pode-se <\/b><\/span><\/span><\/span>concluir que o pr\u00f3ximo choque <\/b><\/span><\/span><\/span>entre elas <\/b><\/span><\/span><\/span>ocorrer\u00e1 nas vizinhan\u00e7as da posi\u00e7\u00e3o<\/b><\/span><\/span><\/span><\/p>\n

a) <\/b><\/span><\/span><\/span>3\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/b><\/span><\/span><\/span><\/p>\n

b) <\/b><\/span><\/span><\/span>5\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/b><\/span><\/span><\/span><\/p>\n

c) <\/b><\/span><\/span><\/span>6\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/b><\/span><\/span><\/span><\/p>\n

d) <\/b><\/span><\/span><\/span>7\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/b><\/span><\/span><\/span><\/p>\n

e) <\/b><\/span><\/span><\/span>8<\/b><\/span><\/span><\/span><\/p>\n

18- Fuvest-SP)<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>Dois caixotes <\/b><\/span><\/span><\/span>de <\/b><\/span><\/span><\/span>mesma altura e mesma massa, A e B, <\/b><\/span><\/span><\/span>podem <\/b><\/span><\/span><\/span>movimentar-se sobre uma superf\u00edcie plana, sem atrito.<\/b><\/span><\/span><\/span> <\/b><\/p>\n

Estando <\/b><\/span><\/span><\/span>inicialmente A parado, pr\u00f3ximo a uma parede, o caixote B aproxima-se perpendicularmente \u00e0 parede, com velocidade V<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sub><\/span>,<\/b><\/span><\/span><\/span> provocando uma <\/b><\/span><\/span><\/span>sucess\u00e3o de colis\u00f5es el\u00e1sticas no plano da figura.<\/b><\/span><\/span><\/span>\"\"<\/p>\n

Ap\u00f3s <\/b><\/span><\/span><\/span>todas as colis\u00f5es<\/b><\/span><\/span><\/span>, \u00e9 <\/b><\/span><\/span><\/span>poss\u00edvel afirmar que os m\u00f3dulos das velocidades dos dois blocos ser\u00e3o <\/b><\/span><\/span><\/span>aproximadamente:<\/b><\/span><\/span><\/span><\/p>\n

a) V<\/b><\/span><\/span><\/span>A<\/b><\/span><\/span><\/sub><\/span>\u00a0= V<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sub><\/span>\u00a0<\/b><\/span><\/span><\/span>e <\/b><\/span><\/span><\/span>V<\/b><\/span><\/span><\/span>B<\/b><\/span><\/span><\/sub><\/span>\u00a0= 0.<\/b><\/span><\/span><\/span>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/b><\/span><\/span><\/span><\/p>\n

b) V<\/b><\/span><\/span><\/span>A<\/b><\/span><\/span><\/sub><\/span>\u00a0= V<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sub><\/span>\/2 <\/b><\/span><\/span><\/span>e <\/b><\/span><\/span><\/span>V<\/b><\/span><\/span><\/span>B<\/b><\/span><\/span><\/sub><\/span>\u00a0= 2 V<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sub><\/span>.<\/b><\/span><\/span><\/span>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/b><\/span><\/span><\/span><\/p>\n

c) V<\/b><\/span><\/span><\/span>A<\/b><\/span><\/span><\/sub><\/span>\u00a0= 0 <\/b><\/span><\/span><\/span>e <\/b><\/span><\/span><\/span>V<\/b><\/span><\/span><\/span>B<\/b><\/span><\/span><\/sub><\/span>\u00a0= 2 V<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sub><\/span>.<\/b><\/span><\/span><\/span>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/b><\/span><\/span><\/span><\/p>\n

d) V<\/b><\/span><\/span><\/span>A<\/b><\/span><\/span><\/sub><\/span>\u00a0= V<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sub><\/span>\/\u221a2 <\/b><\/span><\/span><\/span>e <\/b><\/span><\/span><\/span>V<\/b><\/span><\/span><\/span>B<\/b><\/span><\/span><\/sub><\/span>\u00a0= V<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sub><\/span>\/\u221a2
\ne) V<\/b><\/span><\/span><\/span>A<\/b><\/span><\/span><\/sub><\/span>\u00a0= 0 <\/b><\/span><\/span><\/span>e <\/b><\/span><\/span><\/span>V<\/b><\/span><\/span><\/span>B<\/b><\/span><\/span><\/sub><\/span>\u00a0= V<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sub><\/span>.<\/b><\/span><\/span><\/span><\/p>\n

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

19-(MACKENZIE-SP)<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>A <\/b><\/span><\/span><\/span>esfera A, <\/b><\/span><\/span><\/span>de <\/b><\/span><\/span><\/span>massa 2 kg e velocidade 10 m\/s, <\/b><\/span><\/span><\/span>colide com <\/b><\/span><\/span><\/span>outra B de 1 kg, <\/b><\/span><\/span><\/span>que <\/b><\/span><\/span><\/span>se encontra inicialmente em repouso. <\/b><\/span><\/span><\/span><\/p>\n

Em seguida, B colide com a parede P. <\/b><\/span><\/span><\/span><\/p>\n

Os <\/b><\/span><\/span><\/span>choques entre as esferas e entre a esfera B e a parede P s\u00e3o perfeitamente el\u00e1sticos. <\/b><\/span><\/span><\/span><\/p>\n

Despreze os atritos <\/b><\/span><\/span><\/span>e o <\/b><\/span><\/span><\/span>tempo de contato nos choques. <\/b><\/span><\/span><\/span><\/p>\n

A <\/b><\/span><\/span><\/span>dist\u00e2ncia percorrida pela esfera A entre o primeiro e o segundo choque com a esfera B <\/b><\/span><\/span><\/span>\u00e9:<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

<\/a><\/p>\n

20-(Olimp\u00edada Brasileira de F\u00edsica)\u00a0<\/b><\/span><\/span><\/span>S\u00e3o realizadas experi\u00eancias com 5 p\u00eandulos <\/b><\/span><\/span><\/span>de <\/b><\/span><\/span><\/span>mesmos comprimentos.<\/b><\/span><\/span><\/span> <\/b><\/p>\n

As <\/b><\/span><\/span><\/span>massas pendulares s\u00e3o de bolas de bilhar iguais, <\/b><\/span><\/span><\/span>cada uma <\/b><\/span><\/span><\/span>ligeiramente encostada na outra.<\/b><\/span><\/span><\/span><\/p>\n

Experi\u00eancia 1: <\/b><\/span><\/span><\/span>A <\/b><\/span><\/span><\/span>bola 1 <\/b><\/span><\/span><\/span>\u00e9 <\/b><\/span><\/span><\/span>erguida de uma altura H e abandonada. <\/b><\/span><\/span><\/span><\/p>\n

Ela <\/b><\/span><\/span><\/span>colide com a bola 2.<\/b><\/span><\/span><\/span> <\/b><\/p>\n

O <\/b><\/span><\/span><\/span>choque se propaga <\/b><\/span><\/span><\/span>e a <\/b><\/span><\/span><\/span>bola 5 \u00e9 lan\u00e7ada, <\/b><\/span><\/span><\/span>praticamente at\u00e9 a <\/b><\/span><\/span><\/span>mesma altura H.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\u00a0<\/span>Experi\u00eancia 2: <\/b><\/span><\/span><\/span>Agora as <\/b><\/span><\/span><\/span>bolas 1 e 2 s\u00e3o erguidas conforme ilustra a figura e abandonadas. <\/b><\/span><\/span><\/span><\/p>\n

Elas caminham juntas at\u00e9 a colis\u00e3o com a bola 3.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Dois estudantes, M\u00e1rio e Pedro, <\/b><\/span><\/span><\/span>t\u00eam <\/b><\/span><\/span><\/span>respostas diferentes com rela\u00e7\u00e3o \u00e0 previs\u00e3o<\/b><\/span><\/span><\/span> do que <\/b><\/span><\/span><\/span>ir\u00e1 ocorrer ap\u00f3s a propaga\u00e7\u00e3o do choque. <\/b><\/span><\/span><\/span><\/p>\n

M\u00e1rio<\/b><\/span><\/span><\/span> acha que <\/b><\/span><\/span><\/span>somente a bola 5 ir\u00e1 se movimentar, saindo com velocidade duas vezes maior <\/b><\/span><\/span><\/span>que as <\/b><\/span><\/span><\/span>velocidades das bolas 1 e 2 incidentes.<\/b><\/span><\/span><\/span> <\/b><\/p>\n

Pedro acha que as bolas 4 e 5 sair\u00e3o juntas <\/b><\/span><\/span><\/span>com a <\/b><\/span><\/span><\/span>mesma velocidade das bolas incidentes 1 e 2.<\/b><\/span><\/span><\/span><\/p>\n

<\/a> 21-(UNIFESP-SP)\u00a0<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

A <\/b><\/span><\/span><\/span>figura <\/b><\/span><\/span><\/span>mostra a <\/b><\/span><\/span><\/span>situa\u00e7\u00e3o anterior a um choque el\u00e1stico de tr\u00eas bolas id\u00eanticas<\/b><\/span><\/span><\/span>. <\/b><\/span><\/span><\/span><\/p>\n

A <\/b><\/span><\/span><\/span>bola 1 tem velocidade \"\" \u00a0<\/b><\/span><\/span><\/span>; <\/b><\/span><\/span><\/span>as bolas 2 e 3 est\u00e3o em repouso (figura 1).<\/b><\/span><\/span><\/span><\/p>\n

Depois do choque, as bolas passam a ter velocidades \"\"\u00a0, \"\"\u201a e \"\"\u00a0.<\/b><\/span><\/span><\/span><\/p>\n

A <\/b><\/span><\/span><\/span>alternativa que representa uma situa\u00e7\u00e3o poss\u00edvel <\/b><\/span><\/span><\/span>para o <\/b><\/span><\/span><\/span>movimento dessas bolas depois do choque \u00e9:<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

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

22-(UFMG-MG)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

A <\/b><\/span><\/span><\/span>professora Beatriz <\/b><\/span><\/span><\/span>deseja <\/b><\/span><\/span><\/span>medir o coeficiente de restitui\u00e7\u00e3o de algumas bolinhas <\/b><\/span><\/span><\/span>fazendo-as colidir <\/b><\/span><\/span><\/span>com o ch\u00e3o <\/b><\/span><\/span><\/span>em seu laborat\u00f3rio.<\/b><\/span><\/span><\/span>\"\"<\/p>\n

Esse <\/b><\/span><\/span><\/span>coeficiente de restitui\u00e7\u00e3o \u00e9 a raz\u00e3o entre a velocidade da bolinha imediatamente ap\u00f3s a colis\u00e3o e a velocidade da bolinha imediatamente antes da colis\u00e3o.<\/b><\/span><\/span><\/span><\/p>\n

Neste caso, o <\/b><\/span><\/span><\/span>coeficiente s\u00f3 depende dos materiais envolvidos.<\/b><\/span><\/span><\/span><\/p>\n

Nos <\/b><\/span><\/span><\/span>experimentos que a professora realiza,<\/b><\/span><\/span><\/span> a <\/b><\/span><\/span><\/span>for\u00e7a de resist\u00eancia do ar \u00e9 desprez\u00edvel.<\/b><\/span><\/span><\/span><\/p>\n

Inicialmente,<\/b><\/span><\/span><\/span> a professora Beatriz <\/b><\/span><\/span><\/span>solta uma bolinha \u2013 a bolinha 1 \u2013 em queda livre da altura de 1,25 m e verifica que, depois bater no ch\u00e3o, a bolinha retorna at\u00e9 a altura de 0,80 m.<\/b><\/span><\/span><\/span><\/p>\n

1.<\/b><\/span><\/span><\/span> CALCULE a velocidade <\/b><\/span><\/span><\/span>da bolinha no instante em que
\n<\/b><\/span><\/span><\/span>A) <\/b><\/span><\/span><\/span>Ela <\/b><\/span><\/span><\/span>chega <\/b><\/span><\/span><\/span>ao <\/b><\/span><\/span><\/span>ch\u00e3o.<\/b><\/span><\/span><\/span>
\n<\/b><\/span><\/span><\/span>B) <\/b><\/span><\/span><\/span>Ela <\/b><\/span><\/span><\/span>perde o contato <\/b><\/span><\/span><\/span>com o ch\u00e3o, <\/b><\/span><\/span><\/span>na subida<\/b><\/span><\/span><\/span><\/p>\n

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

2.<\/b><\/span><\/span><\/span> Depois de subir <\/b><\/span><\/span><\/span>at\u00e9 a <\/b><\/span><\/span><\/span>altura de 0,80 m, <\/b><\/span><\/span><\/span>a <\/b><\/span><\/span><\/span>bolinha desce e bate pela segunda vez no ch\u00e3o.<\/b><\/span><\/span><\/span><\/p>\n

DETERMINE a velocidade da bolinha imediatamente ap\u00f3s essa segunda batida.<\/b><\/span><\/span><\/span><\/p>\n

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

3.<\/b><\/span><\/span><\/span> <\/b>A seguir, a <\/b><\/span><\/span><\/span>professora Beatriz pega outra bolinha \u2013 a bolinha 2 \u2013, que tem o mesmo tamanho e a mesma massa, mas \u00e9 feita <\/b><\/span><\/span><\/span>de <\/b><\/span><\/span><\/span>material diferente da bolinha 1. <\/b><\/span><\/span><\/span><\/p>\n

Ela <\/b><\/span><\/span><\/span>solta a bolinha 2 em queda livre, tamb\u00e9m da altura de 1,25 m,<\/b><\/span><\/span><\/span> e verifica que <\/b><\/span><\/span><\/span>essa bolinha bate no ch\u00e3o e fica parada, ou seja, o coeficiente de restitui\u00e7\u00e3o \u00e9 nulo.<\/b><\/span><\/span><\/span><\/p>\n

Considere que <\/b><\/span><\/span><\/span>os tempos de colis\u00e3o das bolinhas 1 e 2 com o ch\u00e3o s\u00e3o iguais.<\/b><\/span><\/span><\/span><\/p>\n

Sejam <\/b><\/span><\/span><\/span>F<\/b><\/span><\/span><\/span>1\u00a0<\/b><\/span><\/span><\/sub><\/span>e F<\/b><\/span><\/span><\/span>2\u00a0<\/b><\/span><\/span><\/sub><\/span>os m\u00f3dulos das for\u00e7as que as bolinhas 1 e 2 fazem, respectivamente, sobre o ch\u00e3o durante a colis\u00e3o.<\/b><\/span><\/span><\/span><\/p>\n

ASSINALE<\/b><\/span><\/span><\/span> com um <\/b><\/span><\/span><\/span>X a op\u00e7\u00e3o que indica a rela\u00e7\u00e3o entre F<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>\u00a0e F<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

JUSTIFIQUE\u00a0sua resposta.<\/b><\/span><\/span><\/span><\/p>\n

23-(UFLA-MG)<\/b><\/span><\/span><\/span><\/p>\n

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

Um <\/b><\/span><\/span><\/span>professor de f\u00edsica montou um grupo de dan\u00e7a com 15 alunos. <\/b><\/span><\/span><\/span><\/p>\n

A <\/b><\/span><\/span><\/span>coreografia foi feita de modo que para todos os<\/b><\/span><\/span><\/span> <\/b>movimentos, <\/b><\/span><\/span><\/span>o <\/b><\/span><\/span><\/span>momento linear <\/b><\/span><\/span><\/span>(quantidade de movimento) do <\/b><\/span><\/span><\/span>grupo fosse conservado, ou seja, mantido constante.<\/b><\/span><\/span><\/span><\/p>\n

Em um <\/b><\/span><\/span><\/span>determinado momento, <\/b><\/span><\/span><\/span>todos os alunos <\/b><\/span><\/span><\/span>est\u00e3o parados no centro do palco.<\/b><\/span><\/span><\/span> <\/b><\/p>\n

Ao <\/b><\/span><\/span><\/span>reiniciar a m\u00fasica, tr\u00eas grupos de tr\u00eas alunos cada um saem dan\u00e7ando, cada grupo em sentidos indicados na figura abaixo, contidos no plano do palco, <\/b><\/span><\/span><\/span>com <\/b><\/span><\/span><\/span>velocidade de 5,0 m\/s.<\/b><\/span><\/span><\/span> <\/b>\"\"<\/p>\n

Considerando que <\/b><\/span><\/span><\/span>todos os alunos possuem massas id\u00eanticas, a velocidade, em m\u00f3dulo, <\/b><\/span><\/span><\/span>que o <\/b><\/span><\/span><\/span>quarto grupo, com seis alunos, deve sair dan\u00e7ando para satisfazer \u00e0 coreografia do professor ser\u00e1 de:<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

 <\/p>\n

Confira as resolu\u00e7\u00f5es comentadas<\/span><\/a><\/h3>\n","protected":false},"excerpt":{"rendered":"

DIN\u00c2MICA IMPULSIVA Esse conte\u00fado envolve muita teoria, em caso de d\u00favidas voc\u00ea pode encontr\u00e1-la em: fisicaevestibular.com.br Mec\u00e2nica Impulso e Quantidade de Movimento Conserva\u00e7\u00e3o da Quantidade de Movimento Colis\u00f5es Mec\u00e2nicas. Exerc\u00edcios de Vestibulares com resolu\u00e7\u00f5es comentadas sobre Din\u00e2mica Impulsiva 01-(ITA-SP)\u00a0Um autom\u00f3vel para quase que instantaneamente ao bater frontalmente numa \u00e1rvore. A prote\u00e7\u00e3o oferecida pelo “air-bag”, comparativamente ao carro que dele n\u00e3o<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":2508,"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-2570","page","type-page","status-publish","hentry"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/2570","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=2570"}],"version-history":[{"count":2,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/2570\/revisions"}],"predecessor-version":[{"id":2575,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/2570\/revisions\/2575"}],"up":[{"embeddable":true,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/2508"}],"wp:attachment":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/media?parent=2570"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}