{"id":3125,"date":"2017-08-08T00:00:15","date_gmt":"2017-08-08T00:00:15","guid":{"rendered":"http:\/\/fisicaevestibular.com.br\/novo\/?page_id=3125"},"modified":"2024-06-29T23:43:21","modified_gmt":"2024-06-29T23:43:21","slug":"dinamica","status":"publish","type":"page","link":"https:\/\/fisicaevestibular.com.br\/novo\/vestibulares-recentes\/mecanica\/dinamica\/","title":{"rendered":"Din\u00e2mica"},"content":{"rendered":"

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

Exerc\u00edcios-Vestibulares Recentes por assunto<\/span><\/span><\/span><\/p>\n

2017-2016 e 2015<\/span><\/span><\/span><\/p>\n

APLICA\u00c7\u00d5ES DAS TR\u00caS LEIS DE NEWTON<\/b><\/span><\/span><\/span><\/p>\n

 <\/p>\n

01-(FMJ-SP-017)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Considere um objeto,\u00a0<\/b><\/span><\/span>cuja massa n\u00e3o varia<\/b><\/span><\/span>, se\u00a0<\/b><\/span><\/span>deslocando em uma trajet\u00f3ria retil\u00ednea com velocidade constante<\/b><\/span><\/span>. \u00c9\u00a0<\/b><\/span><\/span>correto afirmar\u00a0<\/b><\/span><\/span>que necessariamente<\/b><\/span><\/span><\/span><\/span><\/p>\n

(A) a\u00a0<\/b><\/span><\/span>resultante das for\u00e7as<\/b><\/span><\/span>\u00a0sobre esse objeto\u00a0<\/b><\/span><\/span>tem dire\u00e7\u00e3o perpendicular \u00e0 da velocidade<\/b><\/span><\/span>.<\/b><\/span><\/span><\/span><\/span><\/p>\n

(B) a\u00a0<\/b><\/span><\/span>resultante das for\u00e7as\u00a0<\/b><\/span><\/span>sobre esse objeto \u00e9\u00a0<\/b><\/span><\/span>igual a seu peso<\/b><\/span><\/span>.<\/b><\/span><\/span><\/span><\/span><\/p>\n

(C) a\u00a0<\/b><\/span><\/span>resultante das for\u00e7as\u00a0<\/b><\/span><\/span>sobre esse objeto tem\u00a0<\/b><\/span><\/span>dire\u00e7\u00e3o e sentido iguais aos da velocidade<\/b><\/span><\/span>.<\/b><\/span><\/span><\/span><\/span><\/p>\n

(D) a\u00a0<\/b><\/span><\/span>resultante das for\u00e7as\u00a0<\/b><\/span><\/span>sobre esse objeto\u00a0<\/b><\/span><\/span>\u00e9 nula<\/b><\/span><\/span>.<\/b><\/span><\/span><\/span><\/span><\/p>\n

(E)\u00a0<\/b><\/span><\/span>n\u00e3o h\u00e1 for\u00e7as agindo sobre esse objeto<\/b><\/span><\/span>.<\/b><\/span><\/span><\/span><\/span><\/p>\n

 <\/p>\n

02-(UNESP-SP-017)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Na\u00a0<\/b><\/span><\/span>linha de produ\u00e7\u00e3o\u00a0<\/b><\/span><\/span>de uma f\u00e1brica, uma\u00a0<\/b><\/span><\/span>esteira rolante movimenta-se no sentido indicado\u00a0<\/b><\/span><\/span>na\u00a0<\/b><\/span><\/span>figura 1<\/b><\/span><\/span>, e\u00a0<\/b><\/span><\/span>com velocidade constante, <\/b><\/span><\/span>transportando\u00a0<\/b><\/span><\/span>caixas de um setor a outro<\/b><\/span><\/span>.<\/b><\/span><\/span><\/span><\/span><\/p>\n

Para fazer uma\u00a0<\/b><\/span><\/span>inspe\u00e7\u00e3o<\/b><\/span><\/span>, um\u00a0<\/b><\/span><\/span>funcion\u00e1rio det\u00e9m uma das caixas, <\/b><\/span><\/span>mantendo-a\u00a0<\/b><\/span><\/span>parada diante de si\u00a0<\/b><\/span><\/span>por\u00a0<\/b><\/span><\/span>alguns segundos<\/b><\/span><\/span>, mas\u00a0<\/b><\/span><\/span>ainda apoiada na esteira que continua rolando,\u00a0<\/b><\/span><\/span>conforme a\u00a0<\/b><\/span><\/span>figura 2.<\/b><\/span><\/span><\/span><\/span>\"\"<\/p>\n

No <\/b><\/span><\/span>intervalo de tempo <\/b><\/span><\/span>em que a\u00a0<\/b><\/span><\/span>esteira continua rolando com velocidade constante\u00a0<\/b><\/span><\/span>e a\u00a0<\/b><\/span><\/span>caixa \u00e9 mantida parada em rela\u00e7\u00e3o ao funcion\u00e1rio (figura 2),<\/b><\/span><\/span>\u00a0a\u00a0<\/b><\/span><\/span>resultante das for\u00e7as aplicadas\u00a0<\/b><\/span><\/span>pela esteira sobre a caixa<\/b><\/span><\/span>\u00a0est\u00e1 corretamente representada\u00a0<\/b><\/span><\/span>na alternativa<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

 <\/p>\n

03-(UNESP-SP-017)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

 <\/p>\n

Tr\u00eas\u00a0<\/b><\/span><\/span>cubos laranjas id\u00eanticos<\/b><\/span><\/span>\u00a0e\u00a0<\/b><\/span><\/span>tr\u00eas cubos azuis id\u00eanticos\u00a0<\/b><\/span><\/span>est\u00e3o <\/b><\/span><\/span>equilibrados em duas balan\u00e7as\u00a0<\/b><\/span><\/span>de\u00a0<\/b><\/span><\/span>pratos, tamb\u00e9m id\u00eanticas,\u00a0<\/b><\/span><\/span>conforme <\/b><\/span><\/span>indicam as figuras.<\/b><\/span><\/span><\/span><\/span>\"\"<\/p>\n

A\u00a0<\/b><\/span><\/span>massa de um cubo laranja supera a de um cubo azul\u00a0<\/b><\/span><\/span>em exato<\/b><\/span><\/span><\/span><\/span><\/p>\n

(A)\u00a0<\/b><\/span><\/span><\/span>1,3 kg.<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

(B)\u00a0<\/b><\/span><\/span><\/span>1,5 kg.<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

(C)\u00a0<\/b><\/span><\/span><\/span>1,2 kg.<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

(D)\u00a0<\/b><\/span><\/span><\/span>1,4 kg.<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

(E)\u00a0<\/b><\/span><\/span>1,6 kg.<\/b><\/span><\/span><\/span><\/span><\/p>\n

04-<\/b><\/span><\/span><\/span>(Medicina \u2013 USCS-SP-017)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

05-<\/b><\/span><\/span><\/span>(FAMERP-SP-017)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Um\u00a0<\/b><\/span><\/span>corpo de massa 8 kg\u00a0<\/b><\/span><\/span>movimenta-se em\u00a0<\/b><\/span><\/span>trajet\u00f3ria retil\u00ednea sobre um plano horizontal<\/b><\/span><\/span>\u00a0e sua\u00a0<\/b><\/span><\/span>posi\u00e7\u00e3o (s) e sua velocidade escalar (v<\/b><\/span><\/span>) variam em<\/b><\/span><\/span>fun\u00e7\u00e3o do tempo (t), conforme\u00a0<\/b><\/span><\/span>os gr\u00e1ficos.<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

a) Determine\u00a0<\/b><\/span><\/span>a\u00a0<\/b><\/span><\/span>posi\u00e7\u00e3o x, em metros,\u00a0<\/b><\/span><\/span>desse corpo no\u00a0<\/b><\/span><\/span>instante t = 10 s.<\/b><\/span><\/span><\/p>\n

b) Calcule<\/b><\/span><\/span>\u00a0o\u00a0<\/b><\/span><\/span>m\u00f3dulo da resultante das for\u00e7as<\/b><\/span><\/span>, em\u00a0<\/b><\/span><\/span>newtons,<\/b><\/span><\/span>\u00a0que\u00a0<\/b><\/span><\/span>atuam sobre o corpo no intervalo de tempo entre t = 6 s e t = 12 s.<\/b><\/span><\/span><\/p>\n

 <\/p>\n

06-(UERJ-RJ-017)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Um\u00a0<\/b><\/span><\/span>reboque de 16 toneladas\u00a0<\/b><\/span><\/span>\u00e9 puxado por um\u00a0<\/b><\/span><\/span>caminh\u00e3o atrav\u00e9s de um cabo de a\u00e7o.<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

Sabe-se que a\u00a0<\/b><\/span><\/span>acelera\u00e7\u00e3o do conjunto caminh\u00e3o-reboque corresponde a 200 cm\/s2,\u00a0<\/b><\/span><\/span>e que a\u00a0<\/b><\/span><\/span>massa do cabo de a\u00e7o \u00e9 desprez\u00edvel em rela\u00e7\u00e3o \u00e0s massas do caminh\u00e3o e do reboque.<\/b><\/span><\/span><\/p>\n

Estime, em newtons,\u00a0<\/b><\/span><\/span>a\u00a0<\/b><\/span><\/span>tra\u00e7\u00e3o no cabo de a\u00e7o.<\/b><\/span><\/span><\/p>\n

07-(UECE-CE-017)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

08-<\/b><\/span><\/span><\/span>(UECE-CE-017)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

09-(UNESP-SP)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Algumas\u00a0<\/b><\/span><\/span>embalagens<\/b><\/span><\/span>\u00a0trazem, impressas em sua superf\u00edcie externa,<\/b><\/span><\/span>informa\u00e7\u00f5es sobre a quantidade m\u00e1xima de caixas iguais a ela que podem ser empilhadas<\/b><\/span><\/span>,\u00a0<\/b><\/span><\/span>sem<\/b><\/span><\/span>que haja\u00a0<\/b><\/span><\/span>risco<\/b><\/span><\/span>\u00a0de\u00a0<\/b><\/span><\/span>danificar a embalagem ou os produtos contidos na primeira caixa da pilha, de baixo para cima.<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

10-<\/b><\/span><\/span><\/span>(PUC-MG-015)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Ap\u00f3s certo tempo de queda,<\/b><\/span><\/span>\u00a0a\u00a0<\/b><\/span><\/span>velocidade de um paraquedista torna-se constante.<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

Nessas condi\u00e7\u00f5es \u00e9\u00a0<\/b><\/span><\/span>CORRETO\u00a0<\/b><\/span><\/span>afirmar:<\/b><\/span><\/span><\/p>\n

a)<\/b><\/span><\/span>\u00a0A acelera\u00e7\u00e3o do paraquedista \u00e9 igual \u00e0 acelera\u00e7\u00e3o da gravidade.<\/b><\/span><\/span><\/p>\n

b)<\/b><\/span><\/span>\u00a0O peso do paraquedista fica nulo.<\/b><\/span><\/span><\/p>\n

c)<\/b><\/span><\/span>\u00a0A acelera\u00e7\u00e3o do paraquedista \u00e9 nula fazendo com que ele flutue no ar.<\/b><\/span><\/span><\/p>\n

d)<\/b><\/span><\/span>\u00a0Ele vai percorrer dist\u00e2ncias iguais no mesmo intervalo do tempo. <\/b><\/span><\/span><\/p>\n

FOR\u00c7A EL\u00c1STICA<\/b><\/span><\/span><\/span><\/p>\n

01-(FAMERP-SP-015)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Uma\u00a0<\/b><\/span><\/span>mola helicoidal<\/b><\/span><\/span>\u00a0de massa desprez\u00edvel e\u00a0<\/b><\/span><\/span>comprimento\u00a0<\/b><\/span><\/span>20 cm<\/b><\/span><\/span>\u00a0\u00e9 presa de modo que seu\u00a0<\/b><\/span><\/span>eixo longitudinal fique na dire\u00e7\u00e3o vertical<\/b><\/span><\/span>. Quando se <\/b><\/span><\/span>prende na mola um objeto de\u00a0<\/b><\/span><\/span>massa 100 g<\/b><\/span><\/span>, ela se\u00a0<\/b><\/span><\/span>deforma at\u00e9 que seu comprimento atinja\u00a0<\/b><\/span><\/span>25 cm.<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

Considere a\u00a0<\/b><\/span><\/span>acelera\u00e7\u00e3o da gravidade igual a\u00a0<\/b><\/span><\/span>10 m\/s<\/b><\/span><\/span>2<\/b><\/span><\/sup><\/span>.<\/b><\/span><\/span><\/p>\n

a)<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>Calcule a\u00a0<\/b><\/span><\/span>constante el\u00e1stica da mola,\u00a0<\/b><\/span><\/span>em N\/m.<\/b><\/span><\/span><\/p>\n

b)<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>Suponha que o\u00a0<\/b><\/span><\/span>objeto seja elevado\u00a0<\/b><\/span><\/span>at\u00e9 a\u00a0<\/b><\/span><\/span>altura em que o comprimento da mola volta a ser\u00a0<\/b><\/span><\/span>20 cm<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>e, em seguida,\u00a0<\/b><\/span><\/span>solto<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>a partir do repouso. <\/b><\/span><\/span>Determine a\u00a0<\/b><\/span><\/span>energia cin\u00e9tica<\/b><\/span><\/span>\u00a0do objeto, em\u00a0<\/b><\/span><\/span>joules<\/b><\/span><\/span>, no instante em que <\/b><\/span><\/span>passa pelo ponto em que o comprimento da mola \u00e9 de 25 cm<\/b><\/span><\/span>. Despreze qualquer perda de energia mec\u00e2nica.<\/b><\/span><\/span><\/p>\n

02-(AFA \u2013 016\/017)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

03-(UECE-CE-017)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Considere\u00a0<\/b><\/span><\/span>duas associa\u00e7\u00f5es de dois pares de molas<\/b><\/span><\/span>, todas\u00a0<\/b><\/span><\/span>iguais, um par em s\u00e9rie\u00a0<\/b><\/span><\/span>e\u00a0<\/b><\/span><\/span>outro em<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

paralelo.<\/b><\/span><\/span><\/p>\n

Os\u00a0<\/b><\/span><\/span>coeficientes el\u00e1sticos das molas equival<\/b><\/span><\/span>entes nas\u00a0<\/b><\/span><\/span>duas associa\u00e7\u00f5es <\/b><\/span><\/span>s\u00e3o<\/b><\/span><\/span><\/p>\n

A)\u00a0<\/b><\/span><\/span>ks\u00e9rie\u00a0> kparalelo\u00a0> 0<\/b><\/span><\/span><\/p>\n

B)\u00a0<\/b><\/span><\/span>kparalelo\u00a0> ks\u00e9rie\u00a0> 0<\/b><\/span><\/span><\/p>\n

C)\u00a0<\/b><\/span><\/span>kparalelo\u00a0= ks\u00e9rie\u00a0> 0<\/b><\/span><\/span><\/p>\n

D)\u00a0<\/b><\/span><\/span>kparalelo\u00a0= ks\u00e9rie\u00a0= 0<\/b><\/span><\/span><\/p>\n

04-<\/b><\/span><\/span><\/span>(FUVEST-SP-015)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

No\u00a0<\/b><\/span><\/span>desenvolvimento do sistema\u00a0<\/b><\/span><\/span>amortecedor<\/b><\/span><\/span>\u00a0de queda de um\u00a0<\/b><\/span><\/span>elevador de massa m<\/b><\/span><\/span>,<\/b><\/span><\/span>\u00a0o engenheiro projetista\u00a0<\/b><\/span><\/span>imp\u00f5e que a mola deve se\u00a0<\/b><\/span><\/span>contrai<\/b><\/span><\/span>r de um\u00a0<\/b><\/span><\/span>valor m\u00e1ximo d<\/b><\/span><\/span>, quando o\u00a0<\/b><\/span><\/span>elevador cai, a\u00a0<\/b><\/span><\/span>partir<\/b><\/span><\/span><\/p>\n

do repouso<\/b><\/span><\/span>, de uma\u00a0<\/b><\/span><\/span>altura h<\/b><\/span><\/span>, como ilustrado na figura abaixo.<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

Para que a\u00a0<\/b><\/span><\/span>exig\u00eancia do projetista seja satisfeita<\/b><\/span><\/span>, a\u00a0<\/b><\/span><\/span>mola a ser empregada deve ter\u00a0<\/b><\/span><\/span>constante el\u00e1stica<\/b><\/span><\/span><\/p>\n

dada por<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

 <\/p>\n

05<\/b><\/span><\/span><\/span>-(UNICAMP-SP-016)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

O\u00a0<\/b><\/span><\/span>trabalho realizado pela fibra sobre a massa, ao se contrair 10%, erguendo a massa at\u00e9 uma nova posi\u00e7\u00e3o de repouso, \u00e9<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

06-<\/b><\/span><\/span><\/span>(UECE-CE-017)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Se\u00a0<\/b><\/span><\/span>fossem desprezados todos os atri<\/b><\/span><\/span>tos e\u00a0<\/b><\/span><\/span>retirados os amortecedores,\u00a0<\/b><\/span><\/span>um <\/b><\/span><\/span>autom\u00f3vel parado\u00a0<\/b><\/span><\/span>em uma\u00a0<\/b><\/span><\/span>via horizontal poderia ser tratado como um sistema massa mola.<\/b><\/span><\/span><\/p>\n

Suponha que a\u00a0<\/b><\/span><\/span>massa suspensa seja de 1.000 kg\u00a0<\/b><\/span><\/span>e que a\u00a0<\/b><\/span><\/span>mola equivalente ao conjunto que o sustenta tenha coeficiente el\u00e1stico<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>k<\/b><\/span><\/span>.<\/b><\/span><\/span>\"\"<\/p>\n

Como\u00a0<\/b><\/span><\/span>h\u00e1 a\u00e7\u00e3o tamb\u00e9m da gravidade,\u00a0<\/b><\/span><\/span>\u00e9\u00a0<\/b><\/span><\/span>correto afirmar\u00a0<\/b><\/span><\/span>que, se o\u00a0<\/b><\/span><\/span>carro oscilar verticalmente,<\/b><\/span><\/span>\u00a0a\u00a0<\/b><\/span><\/span>frequ\u00eancia de oscila\u00e7\u00e3o.<\/b><\/span><\/span><\/p>\n

A) n\u00e3o depende\u00a0<\/b><\/span><\/span>da\u00a0<\/b><\/span><\/span>gravidade<\/b><\/span><\/span>\u00a0e \u00e9\u00a0<\/b><\/span><\/span>fun\u00e7\u00e3o apenas do coeficiente el\u00e1stico k<\/b><\/span><\/span>.<\/b><\/span><\/span><\/p>\n

B)\u00a0<\/b><\/span><\/span>\u00e9\u00a0<\/b><\/span><\/span>fun\u00e7\u00e3o do produto da massa\u00a0<\/b><\/span><\/span>do carro pela\u00a0<\/b><\/span><\/span>gravidade.<\/b><\/span><\/span><\/p>\n

C) n\u00e3o depende da gravidade\u00a0<\/b><\/span><\/span>e \u00e9\u00a0<\/b><\/span><\/span>fun\u00e7\u00e3o da raz\u00e3o entre k e a massa do carro.<\/b><\/span><\/span><\/p>\n

D) depende somente<\/b><\/span><\/span>\u00a0do\u00a0<\/b><\/span><\/span>coeficiente el\u00e1stico k .<\/b><\/span><\/span><\/p>\n

P\u00caNDULOS SIMPLES<\/b><\/span><\/span><\/span><\/p>\n

01-<\/b><\/span><\/span><\/span>(FUVEST-SP-016)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Um p\u00eandulo simples,<\/b><\/span><\/span>\u00a0constitu\u00eddo por um\u00a0<\/b><\/span><\/span>fio de comprimento L e uma pequena esfera,<\/b><\/span><\/span>\u00a0\u00e9 colocado em\u00a0<\/b><\/span><\/span>oscila\u00e7\u00e3o.<\/b><\/span><\/span><\/p>\n

Uma<\/b><\/span><\/span>\u00a0haste horizontal r\u00edgida \u00e9 inserida perpendicularmente ao plano de oscila\u00e7\u00e3o desse p\u00eandulo, interceptando\u00a0<\/b><\/span><\/span>o movimento do fio\u00a0<\/b><\/span><\/span>na metade do seu comprimento,<\/b><\/span><\/span>\u00a0quando ele est\u00e1 na\u00a0<\/b><\/span><\/span>dire\u00e7\u00e3o vertical. A partir desse momento<\/b><\/span><\/span>, o\u00a0<\/b><\/span><\/span>per\u00edodo<\/b><\/span><\/span>\u00a0do movimento da esfera \u00e9\u00a0<\/b><\/span><\/span>dado por<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

02<\/b><\/span><\/span><\/span>-(ENEM-MEC-2014)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Christiaan Huygens,<\/b><\/span><\/span>\u00a0em 1656, criou o\u00a0<\/b><\/span><\/span>rel\u00f3gio de p\u00eandulo. <\/b><\/span><\/span>Nesse dispositivo, a\u00a0<\/b><\/span><\/span>pontualidade<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

baseia-se na\u00a0<\/b><\/span><\/span>regularidade das pequenas oscila\u00e7\u00f5es do p\u00eandulo<\/b><\/span><\/span>. Para<\/b><\/span><\/span>manter a precis\u00e3o<\/b><\/span><\/span>\u00a0desse\u00a0<\/b><\/span><\/span>rel\u00f3gio<\/b><\/span><\/span>,\u00a0<\/b><\/span><\/span>diversos problemas foram contornados. <\/b><\/span><\/span>Por exemplo, a\u00a0<\/b><\/span><\/span>haste passou por ajustes<\/b><\/span><\/span>\u00a0at\u00e9 que, no in\u00edcio do s\u00e9culo XX, <\/b><\/span><\/span>houve uma inova\u00e7\u00e3o<\/b><\/span><\/span>, que foi sua\u00a0<\/b><\/span><\/span>fabrica\u00e7\u00e3o usando uma liga met\u00e1lica que se comporta regularmente em um largo intervalo de temperaturas.
\n<\/b><\/span><\/span>YODER, J. G.\u00a0Unrolling Time: Christiaan Huygens and the mathematization of nature.\u00a0<\/b><\/span><\/span><\/span>Cambridge: Cambridge University P ress, 2004 (adaptado).
\n<\/b><\/span><\/span>Desprezando a presen\u00e7a de\u00a0<\/b><\/span><\/span>for\u00e7as dissipativas<\/b><\/span><\/span>\u00a0 e considerando\u00a0<\/b><\/span><\/span>a acelera\u00e7\u00e3o da gravidade constante<\/b><\/span><\/span>,\u00a0<\/b><\/span><\/span>para que esse tipo de rel\u00f3gio realize corretamente a contagem do tempo<\/b><\/span><\/span>, \u00e9\u00a0<\/b><\/span><\/span>necess\u00e1rio<\/b><\/span><\/span>\u00a0que o(a)<\/b><\/span><\/span><\/p>\n

a)\u00a0<\/b><\/span><\/span>comprimento da haste seja mantido constante.<\/b><\/span><\/span><\/p>\n

b)<\/b><\/span><\/span>\u00a0a massa do corpo suspenso pela haste seja pequena.<\/b><\/span><\/span><\/p>\n

c)<\/b><\/span><\/span>\u00a0da haste possua alta condutividade t\u00e9rmica.<\/b><\/span><\/span><\/p>\n

d)\u00a0<\/b><\/span><\/span>amplitude da oscila\u00e7\u00e3o seja constante a qualquer temperatura.<\/b><\/span><\/span><\/p>\n

e)\u00a0<\/b><\/span><\/span>energia potencial gravitacional do corpo suspenso se mantenha constante.<\/b><\/span><\/span><\/p>\n

PLANO INCLINADO<\/b><\/span><\/span><\/span><\/p>\n

01-(MACKENZIE-SP-2017)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

 <\/p>\n

02-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span>(Faculdade de Tecnologia Termomec\u00e2nica \u2013 SP)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

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

Um menino\u00a0<\/b><\/span><\/span>de 30 kg<\/b><\/span><\/span>,\u00a0<\/b><\/span><\/span>inicialmente em repouso\u00a0<\/b><\/span><\/span>e a\u00a0<\/b><\/span><\/span>4 m do solo<\/b><\/span><\/span>, inicia um movimento de descida de\u00a0<\/b><\/span><\/span>A para B<\/b><\/span><\/span>, como mostra a figura.<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

(http:\/\/3.bp.blogspot.com)<\/b><\/span><\/span><\/p>\n

Ele chega a B<\/b><\/span><\/span>, ao n\u00edvel do solo, com uma\u00a0<\/b><\/span><\/span>velocidade de 6,0 m\/s<\/b><\/span><\/span>. Considerando a\u00a0<\/b><\/span><\/span>acelera\u00e7\u00e3o da gravidade<\/b><\/span><\/span>\u00a0igual a\u00a0<\/b><\/span><\/span>10 m\/s\u00b2<\/b><\/span><\/span>,\u00a0<\/b><\/span><\/span>a energia mec\u00e2nica dissipada pelo atrito<\/b><\/span><\/span>, no movimento apresentado pela figura, \u00e9 de<\/b><\/span><\/span><\/p>\n

(A) 540 J.<\/b><\/span><\/span><\/p>\n

(B) 580 J.<\/b><\/span><\/span><\/p>\n

(C) 620 J.<\/b><\/span><\/span><\/p>\n

(D) 660 J.<\/b><\/span><\/span><\/p>\n

(E) 740 J.<\/b><\/span><\/span><\/p>\n

 <\/p>\n

03-<\/b><\/span><\/span><\/span> <\/b>(AFA \u2013 016\/017)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

04-<\/b><\/span><\/span><\/span>(FAMERP-SP-015)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Uma\u00a0<\/b><\/span><\/span>esquiadora de\u00a0<\/b><\/span><\/span>massa 80 kg<\/b><\/span><\/span>, incluindo\u00a0<\/b><\/span><\/span>todo o equipamento<\/b><\/span><\/span>, desce com\u00a0<\/b><\/span><\/span>velocidade constante por uma rampa plana e\u00a0<\/b><\/span><\/span>inclinada que forma com a\u00a0<\/b><\/span><\/span>horizontal um<\/b><\/span><\/span>\u00e2ngulo \u03b8<\/b><\/span><\/span>, em um local em que a\u00a0<\/b><\/span><\/span>acelera\u00e7\u00e3o da gravidade vale 10 m\/s2.<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

Considere que\u00a0<\/b><\/span><\/span>existe\u00a0<\/b><\/span><\/span>resist\u00eancia do ar<\/b><\/span><\/span>, que o\u00a0<\/b><\/span><\/span>coeficiente de atrito din\u00e2mico entre os esquis e a neve \u00e9 igual a\u00a0<\/b><\/span><\/span>0,10<\/b><\/span><\/span>\u00a0e que\u00a0<\/b><\/span><\/span>sen \u03b8 = 0,6 e cos \u03b8 = 0,8.<\/b><\/span><\/span><\/p>\n

a)<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>Na\u00a0<\/b><\/span><\/span>figura inserida no campo de Resolu\u00e7\u00e3o e Resposta<\/b><\/span><\/span>,\u00a0<\/b><\/span><\/span>represente as for\u00e7as que atuam no conjunto esquiadora mais equipamento.<\/b><\/span><\/span><\/p>\n

b)<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>Calcule o valor da\u00a0<\/b><\/span><\/span>for\u00e7a de resist\u00eancia do ar<\/b><\/span><\/span>,\u00a0<\/b><\/span><\/span>em newtons<\/b><\/span><\/span>, que\u00a0<\/b><\/span><\/span>age sobre o conjunto durante o movimento.<\/b><\/span><\/span><\/p>\n

05-<\/b><\/span><\/span><\/span>(MACKENZIE-SP-2017)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

POLIAS E ROLDANAS<\/b><\/span><\/span><\/span><\/p>\n

 <\/p>\n

01-(ENEM-MEC-016)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Uma\u00a0<\/b><\/span><\/span>inven\u00e7\u00e3o que significou um grande avan\u00e7o tecnol\u00f3gico na Antiguidade,<\/b><\/span><\/span>\u00a0a\u00a0<\/b><\/span><\/span>polia composta<\/b><\/span><\/span>\u00a0ou a\u00a0<\/b><\/span><\/span>associa\u00e7\u00e3o de polias, \u00e9 atribu\u00edda a Arquimedes<\/b><\/span><\/span>\u00a0(287 a.C. a 212 a.C.)<\/b><\/span><\/span>.<\/b><\/span><\/span><\/span><\/span><\/p>\n

O\u00a0<\/b><\/span><\/span>aparato<\/b><\/span><\/span>\u00a0consiste em associar\u00a0<\/b><\/span><\/span>uma serie de polias moveis a uma polia fixa.<\/b><\/span><\/span><\/span><\/span><\/p>\n

A\u00a0<\/b><\/span><\/span>figura\u00a0<\/b><\/span><\/span>exemplifica um\u00a0<\/b><\/span><\/span>arranjo poss\u00edvel para esse aparato.<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\u00c9\u00a0<\/b><\/span><\/span>relatado<\/b><\/span><\/span>\u00a0que\u00a0<\/b><\/span><\/span>Arquimedes\u00a0<\/b><\/span><\/span>teria\u00a0<\/b><\/span><\/span>demonstrado<\/b><\/span><\/span>\u00a0para o rei Hier\u00e3o um\u00a0<\/b><\/span><\/span>outro arranjo desse aparato, movendo sozinho, sobre areias da praia, um navio repleto de passageiros e cargas,<\/b><\/span><\/span>\u00a0algo que seria\u00a0<\/b><\/span><\/span>imposs\u00edvel sem a participa\u00e7\u00e3o de muitos homens.<\/b><\/span><\/span><\/span><\/span><\/p>\n

Suponha que a\u00a0<\/b><\/span><\/span>massa do navio era de 3000 kg,<\/b><\/span><\/span>\u00a0que o\u00a0<\/b><\/span><\/span>coeficiente de atrito est\u00e1tico\u00a0<\/b><\/span><\/span>entre\u00a0<\/b><\/span><\/span>navio e a areia era 0,8<\/b><\/span><\/span>\u00a0e que\u00a0<\/b><\/span><\/span>Arquimedes<\/b><\/span><\/span>\u00a0tenha\u00a0<\/b><\/span><\/span>puxado o navio com uma for\u00e7a\u00a0\"\", paralela \u00e0 dire\u00e7\u00e3o do movimento e de modulo igual a 400 N.<\/b><\/span><\/span><\/span><\/span><\/p>\n

Considere os\u00a0<\/b><\/span><\/span>fios e as polias ideias,<\/b><\/span><\/span>\u00a0a\u00a0<\/b><\/span><\/span>acelera\u00e7\u00e3o da gravidade<\/b><\/span><\/span>\u00a0igual a\u00a0<\/b><\/span><\/span>10 m\/s\u00b2<\/b><\/span><\/span>\u00a0e que a\u00a0<\/b><\/span><\/span>superf\u00edcie da<\/b><\/span><\/span><\/span><\/span><\/p>\n

Praia \u00e9 perfeitamente horizontal.<\/b><\/span><\/span><\/span><\/span><\/p>\n

O\u00a0<\/b><\/span><\/span>n\u00famero m\u00ednimo de polias m\u00f3veis usadas, nessa situa\u00e7\u00e3o<\/b><\/span><\/span>, por Arquimedes foi<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

02-<\/b><\/span><\/span><\/span> (CEDERJ-RJ-2017)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Por meio de um sistema de roldanas, um trabalhador\u00a0<\/b><\/span><\/span>desce, a uma acelera\u00e7\u00e3o constante de 2,0m\/s\u00b2,<\/b><\/span><\/span>\u00a0um engradado contendo duas caixas. Considerando que\u00a0<\/b><\/span><\/span>a acelera\u00e7\u00e3o da gravidade\u00a0<\/b><\/span><\/span>no local \u00e9 igual a\u00a0<\/b><\/span><\/span>10 m\/s\u00b2<\/b><\/span><\/span>, que a\u00a0<\/b><\/span><\/span>caixa superior pesa 300N\u00a0<\/b><\/span><\/span>e a\u00a0<\/b><\/span><\/span>caixa inferior, 500N<\/b><\/span><\/span>, calcule o m\u00f3dulo da for\u00e7a que:\"\"<\/b><\/span><\/span><\/p>\n

a)\u00a0<\/b><\/span><\/span>a caixa inferior exerce sobre a caixa superior<\/b><\/span><\/span>;<\/b><\/span><\/span><\/p>\n

b)\u00a0<\/b><\/span><\/span>o piso do engradado exerce sobre a caixa inferior<\/b><\/span><\/span>.<\/b><\/span><\/span><\/p>\n

03-(UFSC-SC-016)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Um\u00a0<\/b><\/span><\/span>professor de F\u00edsica\u00a0<\/b><\/span><\/span>realiza um\u00a0<\/b><\/span><\/span>experimento sobre din\u00e2mica\u00a0<\/b><\/span><\/span>para mostrar aos seus alunos. Ele\u00a0<\/b><\/span><\/span>puxa um bloco de 400 kg\u00a0<\/b><\/span><\/span>a\u00a0<\/b><\/span><\/span>partir do repouso, <\/b><\/span><\/span>aplicando sobre a corda uma\u00a0<\/b><\/span><\/span>for\u00e7a constante de 350 N<\/b><\/span><\/span>, como mostra a figura abaixo.<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

O sistema \u00e9 constitu\u00eddo por\u00a0<\/b><\/span><\/span>fios inextens\u00edveis\u00a0<\/b><\/span><\/span>e\u00a0<\/b><\/span><\/span>duas roldanas<\/b><\/span><\/span>, todos de<\/b><\/span><\/span>massa desprez\u00edvel.<\/b><\/span><\/span><\/p>\n

Existe atrito entre a superf\u00edcie horizontal e o bloco.<\/b><\/span><\/span>\u00a0Os\u00a0<\/b><\/span><\/span>coeficientes de atrito est\u00e1tico e de atrito cin\u00e9tico s\u00e3o 0,30 e 0,25, respectivamente.<\/b><\/span><\/span><\/p>\n

Com base no que\u00a0<\/b><\/span><\/span>foi exposto, \u00e9 CORRETO\u00a0<\/b><\/span><\/span>afirmar que:<\/b><\/span><\/span><\/p>\n

01.\u00a0<\/b><\/span><\/span>a\u00a0<\/b><\/span><\/span>for\u00e7a de tra\u00e7\u00e3o\u00a0<\/b><\/span><\/span>no fio ligado ao bloco \u00e9 de\u00a0<\/b><\/span><\/span>1400 N.<\/b><\/span><\/span><\/p>\n

02.\u00a0<\/b><\/span><\/span>o\u00a0<\/b><\/span><\/span>bloco adquire\u00a0<\/b><\/span><\/span>uma\u00a0<\/b><\/span><\/span>acelera\u00e7\u00e3o de 2,0 m\/s\u00b2.<\/b><\/span><\/span><\/p>\n

04.\u00a0<\/b><\/span><\/span>apenas\u00a0<\/b><\/span><\/span>tr\u00eas for\u00e7as\u00a0<\/b><\/span><\/span>atuam\u00a0<\/b><\/span><\/span>sobre o bloco: o peso, a for\u00e7a de atrito e a tra\u00e7\u00e3o.<\/b><\/span><\/span><\/p>\n

08<\/b><\/span><\/span>. a\u00a0<\/b><\/span><\/span>for\u00e7a resultante sobre o bloco \u00e9 de 400 N.<\/b><\/span><\/span><\/p>\n

16.\u00a0<\/b><\/span><\/span>a\u00a0<\/b><\/span><\/span>for\u00e7a m\u00ednima<\/b><\/span><\/span>\u00a0que o professor deve aplicar\u00a0<\/b><\/span><\/span>sobre a corda para movimentar o bloco \u00e9 de 290 N.<\/b><\/span><\/span><\/p>\n

FOR\u00c7AS NO MCU<\/b><\/span><\/span><\/span><\/p>\n

01-(FAMERP-SP-017)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Em uma\u00a0<\/b><\/span><\/span>exibi\u00e7\u00e3o de acrobacias a\u00e9reas,<\/b><\/span><\/span>\u00a0um\u00a0<\/b><\/span><\/span>avi\u00e3o\u00a0<\/b><\/span><\/span>pilotado por uma\u00a0<\/b><\/span><\/span>pessoa de 80 kg<\/b><\/span><\/span>\u00a0faz manobras e deixa\u00a0<\/b><\/span><\/span>no ar um rastro de fuma\u00e7a indicando sua trajet\u00f3ria.<\/b><\/span><\/span>\"\"<\/p>\n

Na\u00a0<\/b><\/span><\/span>figura,<\/b><\/span><\/span>\u00a0est\u00e1 representado um\u00a0<\/b><\/span><\/span>looping circular\u00a0<\/b><\/span><\/span>de\u00a0<\/b><\/span><\/span>raio 50 m contido em um plano vertical, descrito por esse avi\u00e3o.<\/b><\/span><\/span><\/p>\n

Adotando\u00a0<\/b><\/span><\/span>g = 10 m\/s2<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>e considerando que ao\u00a0<\/b><\/span><\/span>passar pelo ponto A,<\/b><\/span><\/span>\u00a0ponto\u00a0<\/b><\/span><\/span>mais alto <\/b><\/span><\/span>da\u00a0<\/b><\/span><\/span>trajet\u00f3ria circular,\u00a0<\/b><\/span><\/span>a\u00a0<\/b><\/span><\/span>velocidade\u00a0<\/b><\/span><\/span>do avi\u00e3o \u00e9 de\u00a0<\/b><\/span><\/span>180 km\/h,\u00a0<\/b><\/span><\/span>a\u00a0<\/b><\/span><\/span>intensidade da for\u00e7a exercida pelo assento sobre o piloto, nesse ponto,\u00a0<\/b><\/span><\/span>\u00e9 igual a\u00a0<\/b><\/span><\/span>(A)\u00a0<\/b><\/span><\/span>3 000 N.<\/b><\/span><\/span><\/p>\n

(B)\u00a0<\/b><\/span><\/span>2 800 N.<\/b><\/span><\/span><\/p>\n

(C)\u00a0<\/b><\/span><\/span>3 200 N.<\/b><\/span><\/span><\/p>\n

(D)\u00a0<\/b><\/span><\/span>2 600 N.<\/b><\/span><\/span><\/p>\n

(E)\u00a0<\/b><\/span><\/span>2 400 N.<\/b><\/span><\/span><\/p>\n

02-(AFA \u2013 016\/017)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

03- (UEMG-MG-017)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

TRABALHO E ENERGIA<\/b><\/span><\/span><\/span><\/p>\n

01-(ENEM-MEC-016)<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

02-(FUVEST-SP-017)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

03-(FMJ-SP-017)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

O bate-bate \u00e9 um brinquedo composto por duas esferas de material r\u00edgido presas a dois fios e a um anel. O objetivo do brinquedo consiste em fazer as esferas girarem em sentidos opostos e se chocarem continuamente em cima e embaixo.<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Suponha que as esferas tenham a\u00a0<\/b><\/span><\/span>mesma massa\u00a0<\/b><\/span><\/span>e que suas\u00a0<\/b><\/span><\/span>velocidades escalares sejam iguais antes e depois de cada choque<\/b><\/span><\/span>. Durante os choques,\u00a0<\/b><\/span><\/span>no sistema constitu\u00eddo pelas duas esferas, ocorre<\/b><\/span><\/span><\/span><\/span><\/p>\n

(A)\u00a0<\/b><\/span><\/span>perda<\/b><\/span><\/span>\u00a0de energia cin\u00e9tica e\u00a0<\/b><\/span><\/span>ganho<\/b><\/span><\/span>\u00a0de quantidade de movimento.<\/b><\/span><\/span><\/span><\/span><\/p>\n

(B)\u00a0<\/b><\/span><\/span>perda<\/b><\/span><\/span>\u00a0de energia cin\u00e9tica e\u00a0<\/b><\/span><\/span>conserva\u00e7\u00e3o<\/b><\/span><\/span>\u00a0da quantidade de movimento.<\/b><\/span><\/span><\/span><\/span><\/p>\n

(C)\u00a0<\/b><\/span><\/span>conserva\u00e7\u00e3o<\/b><\/span><\/span>\u00a0da energia cin\u00e9tica e\u00a0<\/b><\/span><\/span>perda<\/b><\/span><\/span>\u00a0da quantidade de movimento.<\/b><\/span><\/span><\/span><\/span><\/p>\n

(D)\u00a0<\/b><\/span><\/span>ganho<\/b><\/span><\/span>\u00a0de energia cin\u00e9tica e\u00a0<\/b><\/span><\/span>perda\u00a0<\/b><\/span><\/span>da quantidade de movimento.<\/b><\/span><\/span><\/span><\/span><\/p>\n

(E)\u00a0<\/b><\/span><\/span>conserva\u00e7\u00e3o<\/b><\/span><\/span>\u00a0de energia cin\u00e9tica e\u00a0<\/b><\/span><\/span>conserva\u00e7\u00e3o<\/b><\/span><\/span>\u00a0da quantidade de movimento.<\/b><\/span><\/span><\/span><\/span><\/p>\n

04-(UNIFESP-SP-017)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Em um\u00a0<\/b><\/span><\/span>teste realizado na investiga\u00e7\u00e3o de um crime,<\/b><\/span><\/span>\u00a0um\u00a0<\/b><\/span><\/span>proj\u00e9til de massa 20 g<\/b><\/span><\/span>\u00a0\u00e9\u00a0<\/b><\/span><\/span>disparado\u00a0<\/b><\/span><\/span>horizontalmente\u00a0<\/b><\/span><\/span>contra um saco de areia apoiado,<\/b><\/span><\/span>\u00a0em<\/b><\/span><\/span>repouso, sobre um carrinho que,<\/b><\/span><\/span>\u00a0tamb\u00e9m\u00a0<\/b><\/span><\/span>em repouso,<\/b><\/span><\/span>\u00a0est\u00e1\u00a0<\/b><\/span><\/span>apoiado sobre uma superf\u00edcie horizontal na qual pode mover-se livre de atrito.<\/b><\/span><\/span><\/p>\n

O proj\u00e9til\u00a0<\/b><\/span><\/span>atravessa o saco perpendicularmente aos eixos das rodas do carrinho<\/b><\/span><\/span>, e\u00a0<\/b><\/span><\/span>sai\u00a0<\/b><\/span><\/span>com\u00a0<\/b><\/span><\/span>velocidade menor que a inicial,<\/b><\/span><\/span>\u00a0enquanto o\u00a0<\/b><\/span><\/span>sistema formado pelo saco de areia e pelo carrinho,<\/b><\/span><\/span>\u00a0que\u00a0<\/b><\/span><\/span>totaliza 100 kg, sai do repouso com velocidade de m\u00f3dulo v.<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

O gr\u00e1fico\u00a0<\/b><\/span><\/span>representa a varia\u00e7\u00e3o da velocidade escalar do proj\u00e9til, v<\/b><\/span><\/span>P<\/b><\/span>,<\/b><\/span><\/span>\u00a0em <\/b><\/span><\/span>fun\u00e7\u00e3o do tempo<\/b><\/span><\/span>, nesse teste.<\/b><\/span><\/span><\/p>\n

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

a)<\/b><\/span><\/span>\u00a0o\u00a0<\/b><\/span><\/span>m\u00f3dulo da velocidade v, em m\/s,<\/b><\/span><\/span>\u00a0adquirida pelo\u00a0<\/b><\/span><\/span>sistema formado pelo saco de areia e pelo<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>carrinho imediatamente ap\u00f3s o saco ter sido atravessado pelo proj\u00e9til.<\/b><\/span><\/span><\/p>\n

b)<\/b><\/span><\/span>\u00a0o\u00a0<\/b><\/span><\/span>trabalho, em joules,<\/b><\/span><\/span>\u00a0realizado pela\u00a0<\/b><\/span><\/span>resultante das for\u00e7as que atuaram sobre o proj\u00e9til no intervalo de tempo em que ele atravessou o saco de areia.<\/b><\/span><\/span><\/p>\n

05-(UNICAMP-SP-017)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Denomina-se\u00a0<\/b><\/span><\/span>energia e\u00f3lica a energia cin\u00e9tica contida no vento.<\/b><\/span><\/span><\/p>\n

Seu\u00a0<\/b><\/span><\/span>aproveitamento<\/b><\/span><\/span>\u00a0ocorre por\u00a0<\/b><\/span><\/span>meio da convers\u00e3o da energia cin\u00e9tica de transla\u00e7\u00e3o em energia cin\u00e9tica de<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>rota\u00e7\u00e3o<\/b><\/span><\/span>\u00a0e, com o emprego de\u00a0<\/b><\/span><\/span>turbinas e\u00f3licas,<\/b><\/span><\/span>\u00a0tamb\u00e9m denominadas\u00a0<\/b><\/span><\/span>aerogeradores,<\/b><\/span><\/span>\u00a0\u00e9\u00a0<\/b><\/span><\/span>gerada energia el\u00e9trica.<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

Indique a\u00a0<\/b><\/span><\/span>regi\u00e3o em quest\u00e3o e qual seria a quantidade de energia el\u00e9trica produzida,<\/b><\/span><\/span>\u00a0se houvesse a\u00a0<\/b><\/span><\/span>redu\u00e7\u00e3o da velocidade do vento pela metade.<\/b><\/span><\/span><\/p>\n

a)<\/b><\/span><\/span>\u00a0Regi\u00e3o Sul; 3.900 MWh.<\/b><\/span><\/span><\/p>\n

b)<\/b><\/span><\/span>\u00a0Regi\u00e3o Nordeste; 1.950 MWh.<\/b><\/span><\/span><\/p>\n

c)<\/b><\/span><\/span>\u00a0Regi\u00e3o Nordeste; 3.900 MWh.<\/b><\/span><\/span><\/p>\n

d)<\/b><\/span><\/span>\u00a0Regi\u00e3o Sul; 1.950 MWh.<\/b><\/span><\/span><\/p>\n

06-(FMABC-SP-017)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

07-<\/b><\/span><\/span><\/span>(COL\u00c9GIO NAVAL \u2013 2016\/17)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

08-<\/b><\/span><\/span><\/span> <\/b>(UEMG-MG-017)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Uma\u00a0<\/b><\/span><\/span>pessoa arrasta uma caixa sobre uma superf\u00edcie sem atrito\u00a0<\/b><\/span><\/span>de\u00a0<\/b><\/span><\/span>duas maneiras distintas,\u00a0<\/b><\/span><\/span>conforme mostram as\u00a0<\/b><\/span><\/span>figuras (a) e (b).<\/b><\/span><\/span><\/p>\n

Nas\u00a0<\/b><\/span><\/span>duas situa\u00e7\u00f5es, o m\u00f3dulo da for\u00e7a exercida pela pessoa \u00e9 igual\u00a0<\/b><\/span><\/span>e se<\/b><\/span><\/span>mant\u00e9m constante ao longo de um mesmo deslocamento.<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

Considerando a\u00a0<\/b><\/span><\/span>for\u00e7a\u00a0\"\",\u00a0<\/b><\/span><\/span>\u00e9\u00a0<\/b><\/span><\/span>correto afirmar\u00a0<\/b><\/span><\/span>que<\/b><\/span><\/span><\/p>\n

a)\u00a0<\/b><\/span><\/span>o\u00a0<\/b><\/span><\/span>trabalho realizado\u00a0<\/b><\/span><\/span>em\u00a0<\/b><\/span><\/span>(a)\u00a0<\/b><\/span><\/span>\u00e9\u00a0<\/b><\/span><\/span>igual ao trabalho realizado<\/b><\/span><\/span>\u00a0em\u00a0<\/b><\/span><\/span>(b).<\/b><\/span><\/span><\/p>\n

b)\u00a0<\/b><\/span><\/span>o\u00a0<\/b><\/span><\/span>trabalho realizado\u00a0<\/b><\/span><\/span>em\u00a0<\/b><\/span><\/span>(a)\u00a0<\/b><\/span><\/span>\u00e9\u00a0<\/b><\/span><\/span>maior do que o trabalho realizado\u00a0<\/b><\/span><\/span>em\u00a0<\/b><\/span><\/span>(b).<\/b><\/span><\/span><\/p>\n

c)\u00a0<\/b><\/span><\/span>o\u00a0<\/b><\/span><\/span>trabalho realizado<\/b><\/span><\/span>\u00a0em\u00a0<\/b><\/span><\/span>(a)\u00a0<\/b><\/span><\/span>\u00e9\u00a0<\/b><\/span><\/span>menor do que o trabalho realizado\u00a0<\/b><\/span><\/span>em\u00a0<\/b><\/span><\/span>(b).<\/b><\/span><\/span><\/p>\n

d) n\u00e3o se pode comparar\u00a0<\/b><\/span><\/span>os\u00a0<\/b><\/span><\/span>trabalhos, porque n\u00e3o se conhece o valor da for\u00e7a.<\/b><\/span><\/span><\/p>\n

09-(UERJ-RJ-016)<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

Atualmente, o\u00a0<\/b><\/span><\/span>navio mais r\u00e1pido do mundo\u00a0<\/b><\/span><\/span>pode navegar em\u00a0<\/b><\/span><\/span>velocidade superior a 100 km\/h.<\/b><\/span><\/span>\"\"<\/p>\n

Em\u00a0<\/b><\/span><\/span>uma de suas viagens,<\/b><\/span><\/span>\u00a0transporta uma<\/b><\/span><\/span>carga de 1000 passageiros e 150 carros.<\/b><\/span><\/span><\/p>\n

Admita,\u00a0<\/b><\/span><\/span>al\u00e9m da massa do navio, de 450000 kg, os seguintes valores m\u00e9dios\u00a0<\/b><\/span><\/span>m<\/b><\/span><\/span>para as\u00a0<\/b><\/span><\/span>demais massas<\/b><\/span><\/span>:\u00a0mpassageiro\u00a0= 70 kg e mcarro\u00a0= 1000 kg.<\/b><\/span><\/span><\/p>\n

Estime, em\u00a0<\/b><\/span><\/span>MJ<\/b><\/span><\/span>, a\u00a0<\/b><\/span><\/span>energia cin\u00e9tica do conjunto<\/b><\/span><\/span>, no\u00a0<\/b><\/span><\/span>instante<\/b><\/span><\/span>\u00a0em que o navio se\u00a0<\/b><\/span><\/span>desloca com velocidade igual a 108 km\/h.<\/b><\/span><\/span><\/p>\n

10-<\/b><\/span><\/span><\/span>(FUVEST-SP-015)<\/b><\/span><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

A\u00a0<\/b><\/span><\/span>figura abaixo<\/b><\/span><\/span>\u00a0mostra o\u00a0<\/b><\/span><\/span>gr\u00e1fico da\u00a0<\/b><\/span><\/span>energia potencial gravitacional U<\/b><\/span><\/span>\u00a0de uma esfera em uma pista, em fun\u00e7\u00e3o da\u00a0<\/b><\/span><\/span>componente horizontal x da posi\u00e7\u00e3o da esfera na pista<\/b><\/span><\/span>.<\/b><\/span><\/span><\/p>\n

se Em\u00a0= Ec\u00a0+ Ep\u00a0= constante, ent\u00e3o no ponto x = x1\u00a0onde a cin\u00e9tica \u00e9 nula a potencial ser\u00e1 m\u00e1xima e a mec\u00e2nica valer\u00e1 Em1\u00a0=0 + E \u2014 Em1\u00a0= E.<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

A esfera \u00e9\u00a0<\/b><\/span><\/span>colocada\u00a0<\/b><\/span><\/span>em repouso<\/b><\/span><\/span>\u00a0na pista, na posi\u00e7\u00e3o de\u00a0<\/b><\/span><\/span>abscissa x = x1,<\/b><\/span><\/span>tendo energia\u00a0<\/b><\/span><\/span>mec\u00e2nica E < 0.\u00a0<\/b><\/span><\/span>A partir dessa condi\u00e7\u00e3o,\u00a0<\/b><\/span><\/span>sua energia cin\u00e9tica<\/b><\/span><\/span>\u00a0tem valor<\/b><\/span><\/span><\/p>\n

a)<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>m\u00e1ximo igual a |Uo|.<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span><\/p>\n

b)<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>igual a |E| quando x = x3.<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span><\/p>\n

c)<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>m\u00ednimo quando x = x2.<\/b><\/span><\/span><\/p>\n

d)<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>m\u00e1ximo quando x = x3.<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span><\/p>\n

e)\u00a0<\/b><\/span><\/span>m\u00e1ximo quando x = x2<\/b><\/span><\/span>.<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

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

 <\/p>\n

01-(ENEM-MEC-016)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

O\u00a0<\/b><\/span><\/span>trilho de ar\u00a0<\/b><\/span><\/span>\u00e9 um\u00a0<\/b><\/span><\/span>dispositivo<\/b><\/span><\/span>\u00a0utilizado em\u00a0<\/b><\/span><\/span>laborat\u00f3rios de f\u00edsica\u00a0<\/b><\/span><\/span>para <\/b><\/span><\/span>analisar movimentos\u00a0<\/b><\/span><\/span>em que\u00a0<\/b><\/span><\/span>corpos de prova\u00a0<\/b><\/span><\/span>(carrinhos) podem se\u00a0<\/b><\/span><\/span>mover com atrito desprez\u00edvel.<\/b><\/span><\/span><\/span><\/span><\/p>\n

A\u00a0<\/b><\/span><\/span>figura ilustra um trilho horizontal com dois carrinhos (1 e 2)\u00a0<\/b><\/span><\/span>em que se<\/b><\/span><\/span>realiza um experimento\u00a0<\/b><\/span><\/span>para obter a\u00a0<\/b><\/span><\/span>massa do carrinho 2.<\/b><\/span><\/span><\/span><\/span><\/p>\n

No i<\/b><\/span><\/span>nstante<\/b><\/span><\/span>\u00a0em que o\u00a0<\/b><\/span><\/span>carrinho1,<\/b><\/span><\/span>\u00a0de\u00a0<\/b><\/span><\/span>massa 150,0 g<\/b><\/span><\/span>,passa a se mover com<\/b><\/span><\/span>velocidade escalar constante, o carrinho 2 est\u00e1 em repouso.<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

No\u00a0<\/b><\/span><\/span>momento em que o carrinho 1\u00a0<\/b><\/span><\/span>se\u00a0<\/b><\/span><\/span>choca com o carrinho 2,ambos<\/b><\/span><\/span>passam a se\u00a0<\/b><\/span><\/span>movimentar juntos\u00a0<\/b><\/span><\/span>com\u00a0<\/b><\/span><\/span>velocidade escalar constante.<\/b><\/span><\/span><\/span><\/span><\/p>\n

Os\u00a0<\/b><\/span><\/span>sensores eletr\u00f4nicos distribu\u00eddos\u00a0<\/b><\/span><\/span>ao\u00a0<\/b><\/span><\/span>longo<\/b><\/span><\/span>\u00a0do trilho\u00a0<\/b><\/span><\/span>determinam as posi\u00e7\u00f5es\u00a0<\/b><\/span><\/span>e registram os\u00a0<\/b><\/span><\/span>instantes associados \u00e0 passagem de cada carrinho, gerando os dados do quadro.<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Com\u00a0<\/b><\/span><\/span>base\u00a0<\/b><\/span><\/span>nos\u00a0<\/b><\/span><\/span>dados experimentais,<\/b><\/span><\/span>\u00a0o\u00a0<\/b><\/span><\/span>valo<\/b><\/span><\/span>r da\u00a0<\/b><\/span><\/span>massa do carrinho 2 \u00e9 igual<\/b><\/span><\/span>\u00a0a<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

02-(PUC-SP-017)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

A figura mostra uma\u00a0<\/b><\/span><\/span>colis\u00e3o envolvendo um\u00a0<\/b><\/span><\/span>trem de carga e uma camionete.<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

Segundo testemunhas, o\u00a0<\/b><\/span><\/span>condutor da camionete teria ignorado o sinal sonoro e avan\u00e7ou a cancela\u00a0<\/b><\/span><\/span>da passagem de n\u00edvel.<\/b><\/span><\/span><\/p>\n

Ap\u00f3s a colis\u00e3o contra a lateral do ve\u00edculo,\u00a0<\/b><\/span><\/span>o\u00a0<\/b><\/span><\/span>carro foi arrastado pelo trem por cerca de 300 metros.\u00a0<\/b><\/span><\/span>Supondo a\u00a0<\/b><\/span><\/span>massa total do trem de 120 toneladas e a da camionete de 3 toneladas, podemos afir<\/b><\/span><\/span>mar que, no\u00a0<\/b><\/span><\/span>momento da colis\u00e3o, a intensidade da for\u00e7a<\/b><\/span><\/span>\u00a0que<\/b><\/span><\/span><\/p>\n

(A)\u00a0<\/b><\/span><\/span>o trem aplicou na camionete\u00a0<\/b><\/span><\/span>foi 40 vezes maior\u00a0<\/b><\/span><\/span>do que a intensidade da for\u00e7a que a\u00a0<\/b><\/span><\/span>camionete aplicou no trem e a colis\u00e3o foi parcialmente el\u00e1stica.<\/b><\/span><\/span><\/p>\n

(B)\u00a0<\/b><\/span><\/span>o trem aplicou na camionete\u00a0<\/b><\/span><\/span>foi 40 vezes maior<\/b><\/span><\/span>\u00a0do que a intensidade da for\u00e7a que a\u00a0<\/b><\/span><\/span>camionete aplicou no trem e a colis\u00e3o foi inel\u00e1stica.<\/b><\/span><\/span><\/p>\n

(C)\u00a0<\/b><\/span><\/span>a\u00a0<\/b><\/span><\/span>camionete aplicou no trem foi igual \u00e0 intensidade da for\u00e7a que o trem aplicou na camionete\u00a0<\/b><\/span><\/span>e a colis\u00e3o foi\u00a0<\/b><\/span><\/span>parcialmente el\u00e1stica.<\/b><\/span><\/span><\/p>\n

(D)\u00a0<\/b><\/span><\/span>a\u00a0<\/b><\/span><\/span>camionete aplicou no trem foi igual \u00e0 intensidade da for\u00e7a que o trem aplicou na camionete e a colis\u00e3o foi inel\u00e1stica.<\/b><\/span><\/span><\/p>\n

03-(UNICAMP-SP-016)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Beisebol<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>\u00e9 um esporte que envolve o<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>arremesso, com a m\u00e3o, de uma bola de 140 g de massa na<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>dire\u00e7\u00e3o de outro jogador que ir\u00e1 rebat\u00ea-la com um taco s\u00f3lido.<\/b><\/span><\/span><\/p>\n

Considere que, em<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>um arremesso, o\u00a0<\/b><\/span><\/span>m\u00f3dulo da velocidade da bola chegou a 162 km\/h,<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

imediatamente<\/b><\/span><\/span>\u00a0ap\u00f3s deixar a m\u00e3o do arremessador.<\/b><\/span><\/span><\/p>\n

Sabendo que o\u00a0<\/b><\/span><\/span>tempo de contato entre a bola e a m\u00e3o do jogador foi de 0,07 s,<\/b><\/span><\/span>\u00a0o\u00a0<\/b><\/span><\/span>m\u00f3dulo da for\u00e7a<\/b><\/span><\/span><\/p>\n

m\u00e9dia\u00a0<\/b><\/span><\/span>aplicada\u00a0<\/b><\/span><\/span>na bola<\/b><\/span><\/span>\u00a0foi de<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

04-<\/b><\/span><\/span><\/span>(UERJ-RJ-016)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

 <\/p>\n

 <\/p>\n

 <\/p>\n

 <\/p>\n

\"\"<\/p>\n

Observe o<\/b><\/span><\/span>gr\u00e1fico,<\/b><\/span><\/span>\u00a0que indica a<\/b><\/span><\/span>for\u00e7a exercida<\/b><\/span><\/span>por uma m\u00e1quina em fun\u00e7\u00e3o do tempo.<\/b><\/span><\/span><\/p>\n

Admitindo que\u00a0<\/b><\/span><\/span>n\u00e3o h\u00e1 perdas no sistema, estime, em N.s,\u00a0<\/b><\/span><\/span>a\u00a0<\/b><\/span><\/span>impuls\u00e3o fornecida pela m\u00e1quina no intervalo entre 5 e 105 segundos.<\/b><\/span><\/span><\/p>\n

05-(UDESC-SC-016)<\/b><\/span><\/span><\/span><\/p>\n

Em uma\u00a0<\/b><\/span><\/span>colis\u00e3o el\u00e1stica frontal<\/b><\/span><\/span>\u00a0(em uma dimens\u00e3o)\u00a0<\/b><\/span><\/span>entre duas part\u00edculas de massas m<\/b><\/span><\/span>1<\/b><\/span>\u00a0e m<\/b><\/span><\/span>2<\/b><\/span>, a\u00a0<\/b><\/span><\/span>part\u00edcula 2 estava em repouso antes da colis\u00e3o. Analise<\/b><\/span><\/span>\u00a0as\u00a0<\/b><\/span><\/span>proposi\u00e7\u00f5es em rela\u00e7\u00e3o \u00e0 colis\u00e3o<\/b><\/span><\/span>.<\/b><\/span><\/span><\/p>\n

I.<\/b><\/span><\/span>\u00a0A\u00a0<\/b><\/span><\/span>quantidade de movimento e a energia cin\u00e9tica<\/b><\/span><\/span>\u00a0do sistema\u00a0<\/b><\/span><\/span>se conservam<\/b><\/span><\/span>.<\/b><\/span><\/span><\/p>\n

II.<\/b><\/span><\/span>\u00a0Se as\u00a0<\/b><\/span><\/span>massas s\u00e3o iguais,<\/b><\/span><\/span>\u00a0a magnitude da\u00a0<\/b><\/span><\/span>velocidade adquirida pela part\u00edcula 2, ap\u00f3s a colis\u00e3o<\/b><\/span><\/span>, \u00e9\u00a0<\/b><\/span><\/span>igual \u00e0 magnitude da velocidade da part\u00edcula 1, antes da colis\u00e3o.<\/b><\/span><\/span><\/p>\n

III.<\/b><\/span><\/span>\u00a0Se\u00a0<\/b><\/span><\/span>m<\/b><\/span><\/span>1<\/b><\/span>\u00a0\u00e9 maior que m<\/b><\/span><\/span>2<\/b><\/span>, a magnitude da\u00a0<\/b><\/span><\/span>velocidade adquirida pela part\u00edcula 2, ap\u00f3s a colis\u00e3o, ser\u00e1 maior que a magnitude da velocidade da part\u00edcula 1, antes da colis\u00e3o.<\/b><\/span><\/span><\/p>\n

IV.<\/b><\/span><\/span>\u00a0Se\u00a0<\/b><\/span><\/span>m<\/b><\/span><\/span>1<\/b><\/span>\u00a0\u00e9 menor que m<\/b><\/span><\/span>2<\/b><\/span>,<\/b><\/span><\/span>\u00a0o\u00a0<\/b><\/span><\/span>vetor velocidade da part\u00edcula 1, ap\u00f3s a colis\u00e3o, \u00e9 igual ao vetor velocidade que ela tinha antes da colis\u00e3o.<\/b><\/span><\/span><\/p>\n

Assinale a\u00a0<\/b><\/span><\/span>alternativa\u00a0correta:<\/b><\/span><\/span><\/p>\n

A.<\/b><\/span><\/span>\u00a0( ) Somente as afirmativas I e III s\u00e3o verdadeiras.<\/b><\/span><\/span><\/p>\n

B.<\/b><\/span><\/span>\u00a0( ) Somente as afirmativas I, III e IV s\u00e3o verdadeiras.<\/b><\/span><\/span><\/p>\n

C.<\/b><\/span><\/span>\u00a0( ) Somente as afirmativas I, II e III s\u00e3o verdadeiras.<\/b><\/span><\/span><\/p>\n

D.<\/b><\/span><\/span>\u00a0( ) Somente a afirmativa II \u00e9 verdadeira.<\/b><\/span><\/span><\/p>\n

E.<\/b><\/span><\/span>\u00a0( ) Somente a afirmativa IV \u00e9 verdadeira.<\/b><\/span><\/span><\/p>\n

06-<\/b><\/span><\/span><\/span>(ENEM-MEC-2014)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

O\u00a0<\/b><\/span><\/span>p\u00eandulo de Newton<\/b><\/span><\/span>\u00a0pode ser constitu\u00eddo por\u00a0<\/b><\/span><\/span>cinco p\u00eandulos id\u00eanticos<\/b><\/span><\/span>suspensos em um\u00a0<\/b><\/span><\/span>mesmo<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>suporte<\/b><\/span><\/span>. Em um\u00a0<\/b><\/span><\/span>dado instante<\/b><\/span><\/span>, as\u00a0<\/b><\/span><\/span>esferas de tr\u00eas p\u00eandulos s\u00e3o deslocadas para a esquerda e<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>liberadas<\/b><\/span><\/span>,\u00a0<\/b><\/span><\/span>deslocando-se para a direita e\u00a0<\/b><\/span><\/span>colidindo elasticamente<\/b><\/span><\/span>\u00a0com as outras duas esferas, que inicialmente\u00a0<\/b><\/span><\/span>estavam paradas.<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

O\u00a0<\/b><\/span><\/span>movimento dos p\u00eandulos\u00a0<\/b><\/span><\/span>ap\u00f3s a primeira colis\u00e3o<\/b><\/span><\/span>\u00a0est\u00e1 representado em :<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

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

07-<\/b><\/span><\/span><\/span>(UNESP-SP-015)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

O\u00a0<\/b><\/span><\/span>gol\u00a0<\/b><\/span><\/span>da conquista do tetracampeonato pela Alemanha na Copa do Mundo de 2014 foi feito pelo jogador G\u00f6tze. Nessa jogada, ele\u00a0<\/b><\/span><\/span>recebeu um cruzamento<\/b><\/span><\/span>,\u00a0<\/b><\/span><\/span>matou a bola no peito<\/b><\/span><\/span>,\u00a0<\/b><\/span><\/span>amortecendo-a, e chutou de esquerdapara fazer o gol.\u00a0<\/b><\/span><\/span>Considere que,\u00a0<\/b><\/span><\/span>imediatamente antes de tocar o jogador,\u00a0<\/b><\/span><\/span>a bola tinha\u00a0<\/b><\/span><\/span>velocidade de m\u00f3dulo V1\u00a0= 8 m\/s em uma dire\u00e7\u00e3o perpendicular ao seu peito\u00a0<\/b><\/span><\/span>e que,\u00a0<\/b><\/span><\/span>imediatamente depois de tocaro jogador,\u00a0<\/b><\/span><\/span>sua velocidade manteve-se perpendicular ao peito do jogador,<\/b><\/span><\/span>por\u00e9m com m\u00f3dulo V2\u00a0= 0,6 m\/se em\u00a0<\/b><\/span><\/span>sentido contr\u00e1rio.<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

Admita que, nessa jogada, a bola ficou em\u00a0<\/b><\/span><\/span>contato com o peito do jogador por 0,2 s\u00a0<\/b><\/span><\/span>e que, nesse intervalo de tempo, a intensidade da\u00a0<\/b><\/span><\/span>for\u00e7a resultante (FR\u00a0), que atuou sobre ela, variou em fun\u00e7\u00e3o do tempo, conforme o gr\u00e1fico.<\/b><\/span><\/span><\/p>\n

Considerando a\u00a0<\/b><\/span><\/span>massa da bola igual a 0,4 kg,\u00a0<\/b><\/span><\/span>\u00e9 correto afirmar que, nessa jogada, o\u00a0<\/b><\/span><\/span>m\u00f3dulo da for\u00e7a resultante m\u00e1xima que atuou sobre a bola<\/b><\/span><\/span>, indicada no gr\u00e1fico por\u00a0<\/b><\/span><\/span>Fm\u00e1x\u00a0, \u00e9 igual, em newtons, a<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

08-<\/b><\/span><\/span><\/span>(FMABC-SP-015)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Uma\u00a0<\/b><\/span><\/span>bola de futebol de massa\u00a0<\/b><\/span><\/span>m\u00a0<\/b><\/i><\/span><\/span>\u00e9 abandonada<\/b><\/span><\/span>\u00a0verticalmente e atinge a cabe\u00e7a de um jogador com\u00a0<\/b><\/span><\/span>velocidade de m\u00f3dulo\u00a0<\/b><\/span><\/span>vvertical<\/b><\/i><\/span><\/span>. <\/b><\/span><\/span>Instintivamente, o jogador <\/b><\/span><\/span>cabeceia\u00a0<\/b><\/span><\/span>a bola lan\u00e7ando-a\u00a0<\/b><\/span><\/span>na dire\u00e7\u00e3o horizontal com velocidade de m\u00f3dulo\u00a0<\/b><\/span><\/span>v\u00a0horizontal<\/b><\/i><\/span><\/span>.<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

Determine o\u00a0<\/b><\/span><\/span>m\u00f3dulo do impulso da for\u00e7a resultante<\/b><\/span><\/span>\u00a0que a cabe\u00e7a do jogador aplica na bola devido ao cabeceio.<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

09-<\/b><\/span><\/span><\/span>(UERJ-RJ-015)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Admita uma\u00a0<\/b><\/span><\/span>colis\u00e3o frontal totalmente inel\u00e1stica<\/b><\/span><\/span>\u00a0entre um objeto que se move com\u00a0<\/b><\/span><\/span>velocidade<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

inicial vo<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>e outro objeto\u00a0<\/b><\/span><\/span>inicialmente em repouso, ambos com mesma massa.<\/b><\/span><\/span><\/p>\n

Nessa situa\u00e7\u00e3o, a\u00a0<\/b><\/span><\/span>velocidade com a qual os dois objetos se movem ap\u00f3s a colis\u00e3o equivale a:<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

10-<\/b><\/span><\/span><\/span>(UERJ-RJ-015)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Um\u00a0<\/b><\/span><\/span>esquiador<\/b><\/span><\/span>, com\u00a0<\/b><\/span><\/span>70 kg de massa<\/b><\/span><\/span>,\u00a0<\/b><\/span><\/span>colide elasticamente<\/b><\/span><\/span>\u00a0contra uma <\/b><\/span><\/span>\u00e1rvore a uma velocidade de<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

72 km\/h.<\/b><\/span><\/span><\/p>\n

Calcule, em\u00a0<\/b><\/span><\/span>unidades do SI<\/b><\/span><\/span>, o\u00a0<\/b><\/span><\/span>momento linear e a energia cin\u00e9tica<\/b><\/span><\/span>\u00a0do esquiador no\u00a0<\/b><\/span><\/span>instante da colis\u00e3o.<\/b><\/span><\/span><\/p>\n

MOVIMENTO HARM\u00d4NICO SIMPLES<\/b><\/span><\/span><\/span><\/p>\n

01-<\/b><\/span><\/span><\/span> (AFA \u2013 015\/016)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

A\u00a0<\/b><\/span><\/span>figura abaixo<\/b><\/span><\/span>\u00a0mostra uma\u00a0<\/b><\/span><\/span>pequena esfera vazada E,<\/b><\/span><\/span>\u00a0com\u00a0<\/b><\/span><\/span>carga el\u00e9trica q = + 2,0.10-5\u00a0C<\/b><\/span><\/span>\u00a0e\u00a0<\/b><\/span><\/span>massa 80<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>g,<\/b><\/span><\/span>\u00a0perpassada por um eixo retil\u00edneo situado num plano horizontal e\u00a0<\/b><\/span><\/span>distante D = 3m de uma carga puntiforme fixa Q = -3,0.10-6\u00a0C.<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

Se a esfera for\u00a0<\/b><\/span><\/span>abandonada, em repouso, no ponto A, a uma dist\u00e2ncia x,<\/b><\/span><\/span>muito pr\u00f3xima da\u00a0<\/b><\/span><\/span>posi\u00e7\u00e3o de<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>equil\u00edbrio 0<\/b><\/span><\/span>, tal que\u00a0<\/b><\/span><\/span>x\/D << 1<\/b><\/span><\/span>\u00a0a esfera passar\u00e1 a\u00a0<\/b><\/span><\/span>oscilar de MHS, em torno de 0, cuja pulsa\u00e7\u00e3o \u00e9<\/b><\/span><\/span>, em\u00a0<\/b><\/span><\/span>rad\/s,<\/b><\/span><\/span>\u00a0igual a<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

02-<\/b><\/span><\/span><\/span>(FMABC-SP-016<\/b><\/span><\/span><\/span>)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Um oscilador massa-mola ideal<\/b><\/span><\/span>\u00a0\u00e9 montado, conforme indica\u00a0<\/b><\/span><\/span>a figura.<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

03-<\/b><\/span><\/span><\/span>(UFSC-SC-016)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"Din\u00e2mica\"<\/p>\n

Pedro, Tiago, Jo\u00e3o e Felipe resolveram comprar um carro do ano 2000, mas se esqueceram de verificar os registros sobre as revis\u00f5es peri\u00f3dicas. A fim de evitar problemas f\u00edsicos devido ao <\/b><\/span><\/span><\/span>excesso de oscila\u00e7\u00e3o<\/b><\/span><\/span><\/span>\u00a0do carro durante viagens longas, decidem analisar a qualidade dos\u00a0<\/b><\/span><\/span><\/span>amortecedores<\/b><\/span><\/span><\/span>. Eles modelam o carro, na situa\u00e7\u00e3o em que est\u00e3o\u00a0<\/b><\/span><\/span><\/span>os quatro como passageiros, como um \u00fanico corpo sobre uma mola ideal, realizando um MHS<\/b><\/span><\/span><\/span>. Ent\u00e3o, eles fazem tr\u00eas medidas, obtendo os seguintes valores:<\/b><\/span><\/span><\/span><\/p>\n

a)\u00a0<\/b><\/span><\/span><\/span>1000 kg<\/b><\/span><\/span><\/span>\u00a0para a\u00a0<\/b><\/span><\/span><\/span>massa do carro<\/b><\/span><\/span><\/span>;<\/b><\/span><\/span><\/span><\/p>\n

b<\/b><\/span><\/span><\/span>) 250 kg<\/b><\/span><\/span><\/span>\u00a0para a\u00a0<\/b><\/span><\/span><\/span>soma de suas massas<\/b><\/span><\/span><\/span>;<\/b><\/span><\/span><\/span><\/p>\n

c)\u00a0<\/b><\/span><\/span><\/span>5,0 cm<\/b><\/span><\/span><\/span>\u00a0para a\u00a0<\/b><\/span><\/span><\/span>compress\u00e3o da mola<\/b><\/span><\/span><\/span>\u00a0quando os quatro estavam dentro do carro parado.<\/b><\/span><\/span><\/span><\/p>\n

Sobre o\u00a0<\/b><\/span><\/span><\/span>MHS<\/b><\/span><\/span><\/span>\u00a0e com base no exposto acima, \u00e9\u00a0<\/b><\/span><\/span><\/span>CORRETO<\/b><\/span><\/span><\/span>\u00a0afirmar que:<\/b><\/span><\/span><\/span><\/p>\n

01. a\u00a0<\/b><\/span><\/span><\/span>frequ\u00eancia<\/b><\/span><\/span><\/span>\u00a0e o\u00a0<\/b><\/span><\/span><\/span>per\u00edodo<\/b><\/span><\/span><\/span>\u00a0do MHS realizado dependem da<\/b><\/span><\/span><\/span>amplitude<\/b><\/span><\/span><\/span>.<\/b><\/span><\/span><\/span><\/p>\n

02. a\u00a0<\/b><\/span><\/span><\/span>frequ\u00eancia de oscila\u00e7\u00e3o<\/b><\/span><\/span><\/span>\u00a0do carro com os passageiros \u00e9\u00a0de\u00a0\"\"\u00a0Hz:<\/b><\/span><\/span><\/span><\/p>\n

04. a\u00a0<\/b><\/span><\/span><\/span>energia cin\u00e9tica<\/b><\/span><\/span><\/span>\u00a0\u00e9\u00a0<\/b><\/span><\/span><\/span>m\u00e1xima<\/b><\/span><\/span><\/span>\u00a0na\u00a0<\/b><\/span><\/span><\/span>posi\u00e7\u00e3o de equil\u00edbrio<\/b><\/span><\/span><\/span>.<\/b><\/span><\/span><\/span><\/p>\n

08. a\u00a0<\/b><\/span><\/span><\/span>constante el\u00e1stica<\/b><\/span><\/span><\/span>\u00a0da mola \u00e9\u00a0<\/b><\/span><\/span><\/span>25 x 104\u00a0N\/m<\/b><\/span><\/span><\/span>.<\/b><\/span><\/span><\/span><\/p>\n

16. o\u00a0<\/b><\/span><\/span><\/span>per\u00edodo<\/b><\/span><\/span><\/span>\u00a0de oscila\u00e7\u00e3o do carro vazio \u00e9 de\u00a0<\/b><\/span><\/span><\/span>1,0 s<\/b><\/span><\/span><\/span>.<\/b><\/span><\/span><\/span><\/p>\n

 <\/p>\n

Confira as resolu\u00e7\u00f5es comentadas<\/span><\/a><\/h3>\n

 <\/p>\n

Clique aqui para ver sobre o tema!<\/a><\/p>\n

Confira as v\u00eddeo aulas!<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

DIN\u00c2MICA Exerc\u00edcios-Vestibulares Recentes por assunto 2017-2016 e 2015 APLICA\u00c7\u00d5ES DAS TR\u00caS LEIS DE NEWTON   01-(FMJ-SP-017) Considere um objeto,\u00a0cuja massa n\u00e3o varia, se\u00a0deslocando em uma trajet\u00f3ria retil\u00ednea com velocidade constante. \u00c9\u00a0correto afirmar\u00a0que necessariamente (A) a\u00a0resultante das for\u00e7as\u00a0sobre esse objeto\u00a0tem dire\u00e7\u00e3o perpendicular \u00e0 da velocidade. (B) a\u00a0resultante das for\u00e7as\u00a0sobre esse objeto \u00e9\u00a0igual a seu peso. (C) a\u00a0resultante das for\u00e7as\u00a0sobre esse objeto<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":3123,"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-3125","page","type-page","status-publish","hentry"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/3125","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=3125"}],"version-history":[{"count":6,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/3125\/revisions"}],"predecessor-version":[{"id":9856,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/3125\/revisions\/9856"}],"up":[{"embeddable":true,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/3123"}],"wp:attachment":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/media?parent=3125"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}