{"id":2576,"date":"2016-10-26T04:00:24","date_gmt":"2016-10-26T04:00:24","guid":{"rendered":"http:\/\/fisicaevestibular.com.br\/novo\/?page_id=2576"},"modified":"2024-09-02T16:35:47","modified_gmt":"2024-09-02T16:35:47","slug":"trabalho-e-energia","status":"publish","type":"page","link":"https:\/\/fisicaevestibular.com.br\/novo\/raciocinio-logico\/trabalho-e-energia\/","title":{"rendered":"Trabalho e Energia"},"content":{"rendered":"

Trabalho e Energia<\/b><\/span><\/span><\/span><\/p>\n

Como esse conte\u00fado envolve muita teoria, em caso de d\u00favidas voc\u00ea pode encontr\u00e1-la em fisicaevestibular.com.br \u2013 Mec\u00e2nica.<\/b><\/span><\/span><\/span><\/p>\n

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

Trabalho e Energia<\/b><\/span><\/span><\/span><\/p>\n

01-(UERJ-RJ)\u00a0<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Observe as <\/b><\/span><\/span><\/span>situa\u00e7\u00f5es a seguir, <\/b><\/span><\/span><\/span>nas quais um <\/b><\/span><\/span><\/span>homem desloca <\/b><\/span><\/span><\/span>uma <\/b><\/span><\/span><\/span>caixa ao longo <\/b><\/span><\/span><\/span>de um <\/b><\/span><\/span><\/span>trajeto AB de 2,5 m.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

As <\/b><\/span><\/span><\/span>for\u00e7as \"\" e \"\" <\/b><\/span><\/span><\/span>e<\/b><\/span><\/span><\/span>xercidas<\/b><\/span><\/span><\/span> pelo <\/b><\/span><\/span><\/span>homem nas duas situa\u00e7\u00f5es, <\/b><\/span><\/span><\/span>t\u00eam o <\/b><\/span><\/span><\/span>mesmo m\u00f3dulo igual a 0,4 N <\/b><\/span><\/span><\/span>e os <\/b><\/span><\/span><\/span>\u00e2ngulos entre suas dire\u00e7\u00f5es <\/b><\/span><\/span><\/span>e os <\/b><\/span><\/span><\/span>respectivos deslocamentos medem\u00a0\u03b8\u00a0e 2\u03b8.<\/b><\/span><\/span><\/span><\/p>\n

Se <\/b><\/span><\/span><\/span>k \u00e9 o trabalho realizado, <\/b><\/span><\/span><\/span>em <\/b><\/span><\/span><\/span>joules<\/b><\/span><\/span><\/span>, por\u00a0\"\", o <\/b><\/span><\/span><\/span>trabalho realizado por\u00a0\"\"<\/b><\/span><\/span><\/span>\u00a0corresponde a:<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

02-(UEL-PR)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Um <\/b><\/span><\/span><\/span>corpo desloca-se <\/b><\/span><\/span><\/span>em <\/b><\/span><\/span><\/span>linha reta <\/b><\/span><\/span><\/span>sob a <\/b><\/span><\/span><\/span>a\u00e7\u00e3o de uma \u00fanica for\u00e7a paralela \u00e0 trajet\u00f3ria.<\/b><\/span><\/span><\/span> <\/b>\"\"<\/p>\n

No <\/b><\/span><\/span><\/span>gr\u00e1fico representa-se a intensidade (\"\") <\/b><\/span><\/span><\/span>da <\/b><\/span><\/span><\/span>for\u00e7a em fun\u00e7\u00e3o<\/b><\/span><\/span><\/span> da <\/b><\/span><\/span><\/span>dist\u00e2ncia (d) percorrida pelo corpo.<\/b><\/span><\/span><\/span><\/p>\n

Durante<\/b><\/span><\/span><\/span> os <\/b><\/span><\/span><\/span>12m de percurso <\/b><\/span><\/span><\/span>indicados no <\/b><\/span><\/span><\/span>gr\u00e1fico, qual foi o trabalho realizado <\/b><\/span><\/span><\/span>pela <\/b><\/span><\/span><\/span>for\u00e7a<\/b><\/span><\/span><\/span> que <\/b><\/span><\/span><\/span>atua sobre o corpo?<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

03-(UFRN-RN)\u00a0<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Oscarito e Ankito,<\/b><\/span><\/span><\/span> <\/b>oper\u00e1rios <\/b><\/span><\/span><\/span>de constru\u00e7\u00e3o civil, recebem a <\/b><\/span><\/span><\/span>tarefa de erguer, cada um deles,<\/b><\/span><\/span><\/span> um <\/b><\/span><\/span><\/span>balde cheio de concreto,<\/b><\/span><\/span><\/span> desde o <\/b><\/span><\/span><\/span>solo at\u00e9 o topo de dois edif\u00edcios de mesma altura, <\/b><\/span><\/span><\/span>conforme ilustra a <\/b><\/span><\/span><\/span>figura. <\/b><\/span><\/span><\/span> <\/b>Ambos os baldes <\/b><\/span><\/span><\/span>t\u00eam a <\/b><\/span><\/span><\/span>mesma massa.<\/b><\/span><\/span><\/span> <\/b>\"\"<\/p>\n

Oscarito usa um sistema com uma polia fixa <\/b><\/span><\/span><\/span>e <\/b><\/span><\/span><\/span>outra m\u00f3vel <\/b><\/span><\/span><\/span>e <\/b><\/span><\/span><\/span>Ankito um sistema com apenas uma polia fixa. <\/b><\/span><\/span><\/span><\/p>\n

Considere que o <\/b><\/span><\/span><\/span>atrito, as massas das polias e as massas das cordas <\/b><\/span><\/span><\/span>s\u00e3o <\/b><\/span><\/span><\/span>desprez\u00edveis<\/b><\/span><\/span><\/span> e que <\/b><\/span><\/span><\/span>cada balde sobe com velocidade constante.<\/b><\/span><\/span><\/span><\/p>\n

Nessas condi\u00e7\u00f5es, <\/b><\/span><\/span><\/span>para erguer seu balde, <\/b><\/span><\/span><\/span>o <\/b><\/span><\/span><\/span>trabalho realizado <\/b><\/span><\/span><\/span>pela <\/b><\/span><\/span><\/span>for\u00e7a exercida por Oscarito<\/b><\/span><\/span><\/span> \u00e9:<\/b><\/span><\/span><\/span><\/p>\n

a)\u00a0menor\u00a0do que o trabalho <\/b><\/span><\/span><\/span>que a for\u00e7a exercida por <\/b><\/span><\/span><\/span>Ankito realiza,<\/b><\/span><\/span><\/span> e a <\/b><\/span><\/span><\/span>for\u00e7a m\u00ednima que ele<\/b><\/span><\/span><\/span> <\/b>exerce <\/b><\/span><\/span><\/span>\u00e9\u00a0<\/b><\/span><\/span><\/span>menor\u00a0que a for\u00e7a m\u00ednima que Ankito exerce<\/b><\/span><\/span><\/span>.<\/b><\/span><\/span><\/span><\/p>\n

b)\u00a0igual\u00a0ao\u00a0trabalho<\/b><\/span><\/span><\/span> que a for\u00e7a exercida por <\/b><\/span><\/span><\/span>Ankito realiza, <\/b><\/span><\/span><\/span>e a <\/b><\/span><\/span><\/span>for\u00e7a m\u00ednima que ele que ele exerce <\/b><\/span><\/span><\/span>\u00e9\u00a0<\/b><\/span><\/span><\/span>maior\u00a0que a for\u00e7a m\u00ednima que Ankito exerce.<\/b><\/span><\/span><\/span><\/p>\n

c)\u00a0menor\u00a0do que o trabalho <\/b><\/span><\/span><\/span>que a for\u00e7a exercida por <\/b><\/span><\/span><\/span>Ankito realiza,<\/b><\/span><\/span><\/span> e a <\/b><\/span><\/span><\/span>for\u00e7a m\u00ednima que ele que ele exerce<\/b><\/span><\/span><\/span> \u00e9\u00a0<\/b><\/span><\/span><\/span>maior\u00a0que a for\u00e7a m\u00ednima que Ankito exerce.<\/b><\/span><\/span><\/span><\/p>\n

d)\u00a0igual\u00a0ao trabalho <\/b><\/span><\/span><\/span>que a for\u00e7a exercida por <\/b><\/span><\/span><\/span>Ankito realiza, <\/b><\/span><\/span><\/span>e a <\/b><\/span><\/span><\/span>for\u00e7a m\u00ednima que ele que ele exerce <\/b><\/span><\/span><\/span>\u00e9<\/b><\/span><\/span><\/span>\u00a0menor\u00a0que a for\u00e7a m\u00ednima que Ankito exerce.<\/b><\/span><\/span><\/span><\/p>\n

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

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

\"\"<\/p>\n

Em um <\/b><\/span><\/span><\/span>terminal de cargas, <\/b><\/span><\/span><\/span>uma <\/b><\/span><\/span><\/span>esteira rolante \u00e9 utilizada <\/b><\/span><\/span><\/span>para <\/b><\/span><\/span><\/span>transportar caixas iguais, <\/b><\/span><\/span><\/span>de <\/b><\/span><\/span><\/span>massa M<\/b><\/span><\/span><\/span> <\/b>= 80 kg, <\/b><\/span><\/span><\/span>com <\/b><\/span><\/span><\/span>centros igualmente espa\u00e7ados de 1 m. <\/b><\/span><\/span><\/span><\/p>\n

Quando a <\/b><\/span><\/span><\/span>velocidade da esteira \u00e9 1,5 m\/s, <\/b><\/span><\/span><\/span>a <\/b><\/span><\/span><\/span>pot\u00eancia dos motores <\/b><\/span><\/span><\/span>para mant\u00ea-la em <\/b><\/span><\/span><\/span>movimento \u00e9 P<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sub><\/span>. <\/b><\/span><\/span><\/span>Em um <\/b><\/span><\/span><\/span>trecho de seu percurso, <\/b><\/span><\/span><\/span>\u00e9 <\/b><\/span><\/span><\/span>necess\u00e1rio planejar uma inclina\u00e7\u00e3o para que a esteira eleve <\/b><\/span><\/span><\/span>a <\/b><\/span><\/span><\/span>carga<\/b><\/span><\/span><\/span> a uma <\/b><\/span><\/span><\/span>altura de 5 m, como indicado.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Para <\/b><\/span><\/span><\/span>acrescentar essa rampa <\/b><\/span><\/span><\/span>e manter a <\/b><\/span><\/span><\/span>velocidade da esteira<\/b><\/span><\/span><\/span>, os <\/b><\/span><\/span><\/span>motores devem passar a fornecer uma pot\u00eancia adicional aproximada de<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

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

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

\"\"<\/p>\n

A <\/b><\/span><\/span><\/span>usina hidrel\u00e9trica <\/b><\/span><\/span><\/span>de <\/b><\/span><\/span><\/span>Itaipu<\/b><\/span><\/span><\/span> possui <\/b><\/span><\/span><\/span>20 turbinas, cada uma <\/b><\/span><\/span><\/span>fornecendo uma <\/b><\/span><\/span><\/span>pot\u00eancia el\u00e9trica \u00fatil <\/b><\/span><\/span><\/span>de <\/b><\/span><\/span><\/span>680 MW,<\/b><\/span><\/span><\/span> a <\/b><\/span><\/span><\/span>partir de um desn\u00edvel de \u00e1gua de 120 m.<\/b><\/span><\/span><\/span>\"\"<\/p>\n

No complexo, constru\u00eddo no <\/b><\/span><\/span><\/span>Rio Paran\u00e1, <\/b><\/span><\/span><\/span>as <\/b><\/span><\/span><\/span>\u00e1guas<\/b><\/span><\/span><\/span> da represa <\/b><\/span><\/span><\/span>passam em cada turbina com vaz\u00e3o de 600 m<\/b><\/span><\/span><\/span>3<\/b><\/span><\/span><\/sup><\/span>\/s. (g = 10m\/s<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sup><\/span>) e d<\/b><\/span><\/span><\/span>\u00e1gua <\/b><\/span><\/span><\/sub><\/span>= 10<\/b><\/span><\/span><\/span>3 <\/b><\/span><\/span><\/sup><\/span>kg\/m<\/b><\/span><\/span><\/span>3<\/b><\/span><\/span><\/sup><\/span>)<\/b><\/span><\/span><\/span><\/p>\n

a) Estime<\/b><\/span><\/span><\/span> o <\/b><\/span><\/span><\/span>n\u00famero de domic\u00edlios, N, <\/b><\/span><\/span><\/span>que <\/b><\/span><\/span><\/span>deixariam de ser atendidos <\/b><\/span><\/span><\/span>se, <\/b><\/span><\/span><\/span>pela queda de um raio, uma dessas turbinas interrompesse sua opera\u00e7\u00e3o entre 17h 30min e 20h30 min, considerando que o consumo m\u00e9dio de energia, por domic\u00edlio, nesse per\u00edodo, seja de 4 kWh.<\/b><\/span><\/span><\/span><\/p>\n

b) Estime<\/b><\/span><\/span><\/span> a <\/b><\/span><\/span><\/span>massa M, em kg<\/b><\/span><\/span><\/span>, de <\/b><\/span><\/span><\/span>\u00e1gua do rio <\/b><\/span><\/span><\/span>que <\/b><\/span><\/span><\/span>entra em cada turbina, a cada segundo.<\/b><\/span><\/span><\/span><\/p>\n

c) Estime<\/b><\/span><\/span><\/span> a <\/b><\/span><\/span><\/span>pot\u00eancia mec\u00e2nica da \u00e1gua P, em MW, em cada turbina.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

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

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

\"\"<\/p>\n

Calcule a <\/b><\/span><\/span><\/span>\u00e1rea \u00fatil das placas de energia solar <\/b><\/span><\/span><\/span>de um <\/b><\/span><\/span><\/span>sistema de aquecimento de \u00e1gua, <\/b><\/span><\/span><\/span>para uma <\/b><\/span><\/span><\/span>resid\u00eancia com quatro moradores<\/b><\/span><\/span><\/span>, visando manter um <\/b><\/span><\/span><\/span>acr\u00e9scimo m\u00e9dio de 30,0\u00b0 C em rela\u00e7\u00e3o \u00e0 temperatura ambiente.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Considere que <\/b><\/span><\/span><\/span>cada pessoa gasta 30,0 litros de \u00e1gua quente por dia <\/b><\/span><\/span><\/span>e que, na <\/b><\/span><\/span><\/span>latitude geogr\u00e1fica <\/b><\/span><\/span><\/span>da resid\u00eancia, a <\/b><\/span><\/span><\/span>convers\u00e3o m\u00e9dia mensal de energia \u00e9 de 60,0 kWh\/m\u00eas por metro quadrado <\/b><\/span><\/span><\/span>de <\/b><\/span><\/span><\/span>superf\u00edcie coletora. <\/b><\/span><\/span><\/span><\/p>\n

Considere ainda que o <\/b><\/span><\/span><\/span>reservat\u00f3rio de \u00e1gua quente <\/b><\/span><\/span><\/span>com <\/b><\/span><\/span><\/span>capacidade para 200 litros <\/b><\/span><\/span><\/span>apresente uma <\/b><\/span><\/span><\/span>perda de energia de 0,30 kWh por m\u00eas para cada litro. <\/b><\/span><\/span><\/span><\/p>\n

\u00c9 dado o <\/b><\/span><\/span><\/span>calor espec\u00edfico da \u00e1gua c = 4,19 J\/g\u00b0C e a densidade da \u00e1gua 1kg\/L.<\/b><\/span><\/span><\/span><\/p>\n

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

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

\"\"<\/p>\n

Um <\/b><\/span><\/span><\/span>carro de corrida de massa m = 800kg,<\/b><\/span><\/span><\/span> percorre uma <\/b><\/span><\/span><\/span>pista de prova plana com velocidade constante V<\/b><\/span><\/span><\/span>o <\/b><\/span><\/span><\/sub><\/span>= 60 m\/s.<\/b><\/span><\/span><\/span><\/p>\n

Nessa situa\u00e7\u00e3o, <\/b><\/span><\/span><\/span>observa-se que a pot\u00eancia desenvolvida pelo motor P<\/b><\/span><\/span><\/span>1 <\/b><\/span><\/span><\/sub><\/span>= 120 kW, <\/b><\/span><\/span><\/span>\u00e9 praticamente <\/b><\/span><\/span><\/span>utilizada para vencer a resist\u00eancia do ar Situa\u00e7\u00e3o 1, pista horizontal).<\/b><\/span><\/span><\/span><\/p>\n

Prosseguindo com os testes, <\/b><\/span><\/span><\/span>faz-se o <\/b><\/span><\/span><\/span>carro descer uma ladeira, <\/b><\/span><\/span><\/span>com o <\/b><\/span><\/span><\/span>motor desligado,<\/b><\/span><\/span><\/span> de forma que <\/b><\/span><\/span><\/span>mantenha a mesma velocidade V<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sub><\/span>\u00a0<\/b><\/span><\/span><\/span>e que <\/b><\/span><\/span><\/span>enfrente a mesma resist\u00eancia do ar <\/b><\/span><\/span><\/span>(situa\u00e7\u00e3o 2, inclina\u00e7\u00e3o\u00a0\u03b1).<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Finalmente,<\/b><\/span><\/span><\/span> faz-se o <\/b><\/span><\/span><\/span>carro subir uma ladeira, <\/b><\/span><\/span><\/span>com a <\/b><\/span><\/span><\/span>mesma velocidade V<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sub><\/span>, sujeito <\/b><\/span><\/span><\/span>\u00e0 mesma resist\u00eancia do ar <\/b><\/span><\/span><\/span>(situa\u00e7\u00e3o 3, inclina\u00e7\u00e3o\u00a0\u03b8)<\/b><\/span><\/span><\/span><\/p>\n

a) <\/b><\/span><\/span><\/span>Estime, para a <\/b><\/span><\/span><\/span>situa\u00e7\u00e3o 1, o valor da for\u00e7a de resist\u00eancia do ar F<\/b><\/span><\/span><\/span>R<\/b><\/span><\/span><\/sub><\/span>, <\/b><\/span><\/span><\/span>em <\/b><\/span><\/span><\/span>newtons,<\/b><\/span><\/span><\/span> que <\/b><\/span><\/span><\/span>age sobre o carro no sentido oposto a seu movimento.<\/b><\/span><\/span><\/span><\/p>\n

b) <\/b><\/span><\/span><\/span>Estime, para a <\/b><\/span><\/span><\/span>situa\u00e7\u00e3o 2,<\/b><\/span><\/span><\/span> o <\/b><\/span><\/span><\/span>seno do \u00e2ngulo de inclina\u00e7\u00e3o da ladeira, sen\u03b1, <\/b><\/span><\/span><\/span>para que o carro <\/b><\/span><\/span><\/span>des\u00e7a a ladeira com velocidade de 60m\/s, constante.<\/b><\/span><\/span><\/span><\/p>\n

c) <\/b><\/span><\/span><\/span>Estime, para a <\/b><\/span><\/span><\/span>situa\u00e7\u00e3o 3, <\/b><\/span><\/span><\/span>a <\/b><\/span><\/span><\/span>pot\u00eancia P<\/b><\/span><\/span><\/span>3<\/b><\/span><\/span><\/sub><\/span>\u00a0do motor, em kW, <\/b><\/span><\/span><\/span>para que o carro <\/b><\/span><\/span><\/span>suba uma ladeira de inclina\u00e7\u00e3o dada por sen\u03b8=0,3, mantendo a velocidade V<\/b><\/span><\/span><\/span>o <\/b><\/span><\/span><\/sub><\/span>= 60m\/s.<\/b><\/span><\/span><\/span><\/p>\n

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

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

\"\"<\/p>\n

\"\"<\/p>\n

O <\/b><\/span><\/span><\/span>texto descreve <\/b><\/span><\/span><\/span>um <\/b><\/span><\/span><\/span>teste de avalia\u00e7\u00e3o de um ve\u00edculo importado, <\/b><\/span><\/span><\/span>lan\u00e7ado neste ano no mercado brasileiro. Sabendo que a <\/b><\/span><\/span><\/span>massa desse carro \u00e9 de 2 400 kg, <\/b><\/span><\/span><\/span>e <\/b><\/span><\/span><\/span>admitindo 1 cv = 740 W e 100 km\/h = 28 m\/s, pode-se afirmar <\/b><\/span><\/span><\/span>que, para <\/b><\/span><\/span><\/span>atingir os 100 km\/h iniciais, a pot\u00eancia \u00fatil m\u00e9dia desenvolvida durante o teste, em rela\u00e7\u00e3o \u00e0 pot\u00eancia total do carro, foi,<\/b><\/span><\/span><\/span> aproximadamente de<\/b><\/span><\/span><\/span><\/p>\n

a) <\/b><\/span><\/span><\/span>90%.\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/b><\/span><\/span><\/span>b) <\/b><\/span><\/span><\/span>75%.\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/b><\/span><\/span><\/span>c) <\/b><\/span><\/span><\/span>60%.\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>d) <\/b><\/span><\/span><\/span>45%.\u00a0\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>e) <\/b><\/span><\/span><\/span>30%.<\/b><\/span><\/span><\/span><\/p>\n

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

09-(FGV-SP)\u00a0<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Conhecido como <\/b><\/span><\/span><\/span>parafuso de Arquimedes,<\/b><\/span><\/span><\/span> este dispositivo foi <\/b><\/span><\/span><\/span>utilizado pelos eg\u00edpcios <\/b><\/span><\/span><\/span>para <\/b><\/span><\/span><\/span>retirar \u00e1gua do Nilo.<\/b><\/span><\/span><\/span> <\/b><\/p>\n

Um <\/b><\/span><\/span><\/span>modelo simples <\/b><\/span><\/span><\/span>pode ser <\/b><\/span><\/span><\/span>constru\u00eddo com uma mangueira enrolada em uma haste reta. <\/b><\/span><\/span><\/span><\/p>\n

Quando a <\/b><\/span><\/span><\/span>haste \u00e9 girada no sentido conveniente, <\/b><\/span><\/span><\/span>a <\/b><\/span><\/span><\/span>extremidade inferior da mangueira entra <\/b><\/span><\/span><\/span>e <\/b><\/span><\/span><\/span>sai da \u00e1gua, aprisionando uma por\u00e7\u00e3o desta no interior da mangueira. <\/b><\/span><\/span><\/span><\/p>\n

Enquanto <\/b><\/span><\/span><\/span>o parafuso gira, a \u00e1gua capturada \u00e9 obrigada a subir at\u00e9 o outro extremo da mangueira, onde \u00e9 despejada.<\/b><\/span><\/span><\/span>\"\"<\/p>\n

Com <\/b><\/span><\/span><\/span>um desses dispositivos, elevou-se \u00e1gua proveniente de um rio at\u00e9 um reservat\u00f3rio, localizado <\/b><\/span><\/span><\/span>a <\/b><\/span><\/span><\/span>2,0 m de altura em rela\u00e7\u00e3o ao n\u00edvel de \u00e1gua desse rio.<\/b><\/span><\/span><\/span> <\/b><\/p>\n

O <\/b><\/span><\/span><\/span>parafuso de Arquimedes utilizado tinha 100 voltas completas d<\/b><\/span><\/span><\/span>e uma mangueira de borracha, sendo que <\/b><\/span><\/span><\/span>cada anel podia transportar 1,0 cm<\/b><\/span><\/span><\/span>3<\/b><\/span><\/span><\/sup><\/span>\u00a0de \u00e1gua. <\/b><\/span><\/span><\/span><\/p>\n

Desconsiderando <\/b><\/span><\/span><\/span>atritos<\/b><\/span><\/span><\/span> e supondo uma <\/b><\/span><\/span><\/span>rota\u00e7\u00e3o uniforme, <\/b><\/span><\/span><\/span>admitindo que o <\/b><\/span><\/span><\/span>tempo necess\u00e1rio para que o parafuso girasse 360\u00ba em torno de seu eixo era de 2,0 s, a pot\u00eancia \u00fatil da fonte do movimento de rota\u00e7\u00e3o, em W, <\/b><\/span><\/span><\/span>era de<\/b><\/span><\/span><\/span>: Dado: <\/b><\/span><\/span><\/span>densidade da \u00e1gua = <\/b><\/span><\/span><\/span>1,0 g\/cm<\/b><\/span><\/span><\/span>3<\/b><\/span><\/span><\/sup><\/span>; <\/b><\/span><\/span><\/span>acelera\u00e7\u00e3o da gravidade = <\/b><\/span><\/span><\/span>10 m\/s<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sup><\/span><\/p>\n

\"\"<\/p>\n

10-(AFA)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

O <\/b><\/span><\/span><\/span>motor de um determinado ve\u00edculo <\/b><\/span><\/span><\/span>consome <\/b><\/span><\/span><\/span>8,0 litros de combust\u00edvel em uma hora. <\/b><\/span><\/span><\/span><\/p>\n

Sabendo-se que o <\/b><\/span><\/span><\/span>calor de combust\u00e3o <\/b><\/span><\/span><\/span>desse combust\u00edvel \u00e9 de <\/b><\/span><\/span><\/span>10 000 cal\/g, <\/b><\/span><\/span><\/span>que sua <\/b><\/span><\/span><\/span>densidade \u00e9 0,675g\/cm<\/b><\/span><\/span><\/span>3<\/b><\/span><\/span><\/sup><\/span>\u00a0<\/b><\/span><\/span><\/span>e que o <\/b><\/span><\/span><\/span>motor <\/b><\/span><\/span><\/span>desenvolve uma <\/b><\/span><\/span><\/span>pot\u00eancia de 24 kW, o rendimento desse motor, em porcentagem, <\/b><\/span><\/span><\/span>\u00e9 de <\/b><\/span><\/span><\/span>(<\/b><\/span><\/span><\/span>considere <\/b><\/span><\/span><\/span>1 cal = 4 J)<\/b><\/span><\/span><\/span>\"\"<\/p>\n

a) <\/b><\/span><\/span><\/span><\/span>32\u00a0\u00a0\u00a0\u00a0\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><\/span><\/p>\n

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

c) <\/b><\/span><\/span><\/span><\/span>40 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\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><\/span><\/p>\n

d) <\/b><\/span><\/span><\/span><\/span>44<\/b><\/span><\/span><\/span><\/span><\/p>\n

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

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

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

A <\/b><\/span><\/span><\/span>energia que um atleta gasta <\/b><\/span><\/span><\/span>pode ser <\/b><\/span><\/span><\/span>determinada<\/b><\/span><\/span><\/span> pelo <\/b><\/span><\/span><\/span>volume de oxig\u00eanio <\/b><\/span><\/span><\/span>por ele <\/b><\/span><\/span><\/span>consumido na respira\u00e7\u00e3o. <\/b><\/span><\/span><\/span><\/p>\n

Abaixo est\u00e1 <\/b><\/span><\/span><\/span>apresentado o gr\u00e1fico do volume\u00a0V de oxig\u00eanio, <\/b><\/span><\/span><\/span>em <\/b><\/span><\/span><\/span>litros por minuto, consumido<\/b><\/span><\/span><\/span> por um <\/b><\/span><\/span><\/span>atleta de massa corporal de 70 kg, <\/b><\/span><\/span><\/span>em fun\u00e7\u00e3o de sua <\/b><\/span><\/span><\/span>velocidade, quando ele anda ou corre.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Considerando que para <\/b><\/span><\/span><\/span>cada litro de oxig\u00eanio consumido s\u00e3o gastas 5 kcal <\/b><\/span><\/span><\/span>e usando <\/b><\/span><\/span><\/span>as informa\u00e7\u00f5es do gr\u00e1fico, determine, para esse atleta,<\/b><\/span><\/span><\/span><\/p>\n

a) <\/b><\/span><\/span><\/span>a <\/b><\/span><\/span><\/span>velocidade<\/b><\/span><\/span><\/span> a partir da qual ele passa a <\/b><\/span><\/span><\/span>gastar menos energia correndo do que andando;<\/b><\/span><\/span><\/span><\/p>\n

b) <\/b><\/span><\/span><\/span>a <\/b><\/span><\/span><\/span>quantidade de energia <\/b><\/span><\/span><\/span>por ele gasta <\/b><\/span><\/span><\/span>durante 12 horas de repouso (parado);<\/b><\/span><\/span><\/span><\/p>\n

c) <\/b><\/span><\/span><\/span>a <\/b><\/span><\/span><\/span>pot\u00eancia dissipada, em watts, <\/b><\/span><\/span><\/span>quando ele <\/b><\/span><\/span><\/span>corre a 15 km\/h;<\/b><\/span><\/span><\/span><\/p>\n

d) quantos minutos <\/b><\/span><\/span><\/span>ele deve <\/b><\/span><\/span><\/span>andar, a 7 km\/h, <\/b><\/span><\/span><\/span>para <\/b><\/span><\/span><\/span>gastar a quantidade de energia armazenada com a ingest\u00e3o de uma barra de chocolate de 100 g, cujo conte\u00fado energ\u00e9tico \u00e9 560 kcal.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

12-(ITA-SP)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

No <\/b><\/span><\/span><\/span>interior de um carrinho de massa M<\/b><\/span><\/span><\/span> mantido em <\/b><\/span><\/span><\/span>repouso, uma mola de constante el\u00e1stica k <\/b><\/span><\/span><\/span>encontra-se <\/b><\/span><\/span><\/span>comprimida de uma dist\u00e2ncia x, <\/b><\/span><\/span><\/span>tendo <\/b><\/span><\/span><\/span>uma extremidade presa<\/b><\/span><\/span><\/span> e a outra <\/b><\/span><\/span><\/span>conectada a um bloco de massa m, conforme a figura.<\/b><\/span><\/span><\/span>\"\"<\/p>\n

Sendo o <\/b><\/span><\/span><\/span>sistema ent\u00e3o abandonado <\/b><\/span><\/span><\/span>e considerando que <\/b><\/span><\/span><\/span>n\u00e3o h\u00e1 atrito <\/b><\/span><\/span><\/span>pode-se <\/b><\/span><\/span><\/span>afirmar que o valor inicial da acelera\u00e7\u00e3o do bloco relativa ao carrinho \u00e9<\/b><\/span><\/span><\/span><\/p>\n

A) <\/b><\/span><\/span><\/span><\/span>kx\/m.\u00a0 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/b><\/span><\/span><\/span><\/span><\/p>\n

B) <\/b><\/span><\/span><\/span><\/span>kx\/M.\u00a0 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/b><\/span><\/span><\/span><\/span><\/p>\n

C) <\/b><\/span><\/span><\/span><\/span>kx\/(m + M).\u00a0 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/b><\/span><\/span><\/span><\/span><\/p>\n

D) <\/b><\/span><\/span><\/span><\/span>kx (M \u2013 m)\/mM<\/b><\/span><\/span><\/span><\/span>. \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/b><\/span><\/span><\/span><\/span><\/p>\n

E) <\/b><\/span><\/span><\/span>kx (M + m)\/mM.<\/b><\/span><\/span><\/span><\/p>\n

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

13-(ITA-SP)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Um <\/b><\/span><\/span><\/span>corpo movimenta-se numa superf\u00edcie horizontal sem atrito, <\/b><\/span><\/span><\/span>a partir do <\/b><\/span><\/span><\/span>repouso, <\/b><\/span><\/span><\/span>devido \u00e0 <\/b><\/span><\/span><\/span>\"\"<\/p>\n

a\u00e7\u00e3o cont\u00ednua de<\/b><\/span><\/span><\/span> um <\/b><\/span><\/span><\/span>dispositivo que lhe fornece uma pot\u00eancia mec\u00e2nica constante. <\/b><\/span><\/span><\/span><\/p>\n

Sendo <\/b><\/span><\/span><\/span>\u03bd sua velocidade ap\u00f3s certo tempo t, <\/b><\/span><\/span><\/span>pode-se <\/b><\/span><\/span><\/span>afirmar <\/b><\/span><\/span><\/span>que<\/b><\/span><\/span><\/span><\/p>\n

A (\u00a0\u00a0 ) <\/b><\/span><\/span><\/span>a acelera\u00e7\u00e3o do corpo \u00e9 constante<\/b><\/span><\/span><\/span>. \u00a0\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

B (\u00a0\u00a0 ) <\/b><\/span><\/span><\/span>a dist\u00e2ncia percorrida \u00e9 proporcional a \u03bd<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sup><\/span>.<\/b><\/span><\/span><\/span><\/p>\n

C (\u00a0\u00a0 ) <\/b><\/span><\/span><\/span>o quadrado da velocidade \u00e9 proporcional a t. \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/b><\/span><\/span><\/span><\/p>\n

D (\u00a0\u00a0 ) <\/b><\/span><\/span><\/span>a for\u00e7a que atua sobre o corpo \u00e9 proporcional a\u00a0 t .<\/b><\/span><\/span><\/span><\/p>\n

E (\u00a0\u00a0 ) <\/b><\/span><\/span><\/span>a taxa de varia\u00e7\u00e3o temporal de energia cin\u00e9tica n\u00e3o \u00e9 constante.<\/b><\/span><\/span><\/span><\/p>\n

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

14-(ITA-SP)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

O <\/b><\/span><\/span><\/span>arranjo de polias <\/b><\/span><\/span><\/span>da <\/b><\/span><\/span><\/span>figura<\/b><\/span><\/span><\/span> \u00e9 <\/b><\/span><\/span><\/span>preso ao teto para erguer uma massa de 24 kg, <\/b><\/span><\/span><\/span>sendo os <\/b><\/span><\/span><\/span>fios inextens\u00edveis, <\/b><\/span><\/span><\/span>e <\/b><\/span><\/span><\/span>desprez\u00edveis<\/b><\/span><\/span><\/span>as <\/b><\/span><\/span><\/span>massas das polias e dos fios. <\/b><\/span><\/span><\/span><\/p>\n

Desprezando os atritos, <\/b><\/span><\/span><\/span>determine: (considere <\/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>O valor do <\/b><\/span><\/span><\/span>m\u00f3dulo da for\u00e7a \"\"\u00a0necess\u00e1rio para equilibrar o sistema.<\/b><\/span><\/span><\/span><\/p>\n

2. O valor do <\/b><\/span><\/span><\/span>m\u00f3dulo da for\u00e7a\u00a0\"\"\u00a0necess\u00e1rio para erguer a massa com velocidade constante.<\/b><\/span><\/span><\/span><\/p>\n

3. A <\/b><\/span><\/span><\/span>for\u00e7a (\"\"\u00a0ou peso) <\/b><\/span><\/span><\/span>que <\/b><\/span><\/span><\/span>realiza maior trabalho,<\/b><\/span><\/span><\/span> em m\u00f3dulo, <\/b><\/span><\/span><\/span>durante o tempo T em que a massa est\u00e1 sendo erguida com velocidade constante.<\/b><\/span><\/span><\/span><\/p>\n

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

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

\"\"<\/p>\n

Em uma <\/b><\/span><\/span><\/span>ind\u00fastria, deseja-se transportar 64 caixas <\/b><\/span><\/span><\/span>de <\/b><\/span><\/span><\/span>mesmo peso e tamanho <\/b><\/span><\/span><\/span>do <\/b><\/span><\/span><\/span>piso t\u00e9rreo <\/b><\/span><\/span><\/span>at\u00e9 um <\/b><\/span><\/span><\/span>n\u00edvel superior. <\/b><\/span><\/span><\/span><\/p>\n

Este <\/b><\/span><\/span><\/span>trabalho pode ser realizado por tr\u00eas m\u00e9todos diferentes:<\/b><\/span><\/span><\/span><\/p>\n

1.<\/b><\/span><\/span><\/span> As <\/b><\/span><\/span><\/span>caixas <\/b><\/span><\/span><\/span>ser\u00e3o <\/b><\/span><\/span><\/span>carregadas, uma a uma, por oper\u00e1rios subindo a escada;<\/b><\/span><\/span><\/span><\/p>\n

2. <\/b><\/span><\/span><\/span>As <\/b><\/span><\/span><\/span>caixas<\/b><\/span><\/span><\/span> ser\u00e3o <\/b><\/span><\/span><\/span>colocadas sobre uma esteira rolante com movimento uniforme;<\/b><\/span><\/span><\/span><\/p>\n

3. <\/b><\/span><\/span><\/span>Em uma <\/b><\/span><\/span><\/span>\u00fanica opera\u00e7\u00e3o, as caixas ser\u00e3o elevadas por um guindaste.<\/b><\/span><\/span><\/span><\/p>\n

O <\/b><\/span><\/span><\/span>m\u00e9todo 3 para elevar as caixas \u00e9 o mais r\u00e1pido e o m\u00e9todo 1, o mais lento.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Em <\/b><\/span><\/span><\/span>rela\u00e7\u00e3o \u00e0s situa\u00e7\u00f5es apresentadas, <\/b><\/span><\/span><\/span>assinale a(s) <\/b><\/span><\/span><\/span>proposi\u00e7\u00e3o(\u00f5es) CORRETA(S).<\/b><\/span><\/span><\/span><\/p>\n

01) <\/b><\/span><\/span><\/span>No <\/b><\/span><\/span><\/span>m\u00e9todo 1, <\/b><\/span><\/span><\/span>o <\/b><\/span><\/span><\/span>trabalho r<\/b><\/span><\/span><\/span>ealizado \u00e9 <\/b><\/span><\/span><\/span>64 vezes maior <\/b><\/span><\/span><\/span>do que no <\/b><\/span><\/span><\/span>m\u00e9todo 3.<\/b><\/span><\/span><\/span><\/p>\n

02) <\/b><\/span><\/span><\/span>O <\/b><\/span><\/span><\/span>trabalho<\/b><\/span><\/span><\/span> realizado <\/b><\/span><\/span><\/span>contra a for\u00e7a gravitacional \u00e9 o mesmo em todos os tr\u00eas m\u00e9todos.<\/b><\/span><\/span><\/span><\/p>\n

04) <\/b><\/span><\/span><\/span>O <\/b><\/span><\/span><\/span>maior trabalho <\/b><\/span><\/span><\/span>\u00e9 <\/b><\/span><\/span><\/span>realizado<\/b><\/span><\/span><\/span> pelo guindaste <\/b><\/span><\/span><\/span>(m\u00e9todo 3), pois as caixas est\u00e3o empilhadas.<\/b><\/span><\/span><\/span><\/p>\n

08) <\/b><\/span><\/span><\/span>A <\/b><\/span><\/span><\/span>pot\u00eancia utilizada <\/b><\/span><\/span><\/span>\u00e9 <\/b><\/span><\/span><\/span>quatro vezes maior no m\u00e9todo 1 em rela\u00e7\u00e3o ao m\u00e9todo 3.<\/b><\/span><\/span><\/span><\/p>\n

16) <\/b><\/span><\/span><\/span>A <\/b><\/span><\/span><\/span>pot\u00eancia utilizada no m\u00e9todo 2 \u00e9 maior do que no m\u00e9todo 1.<\/b><\/span><\/span><\/span><\/p>\n

32) <\/b><\/span><\/span><\/span>O <\/b><\/span><\/span><\/span>trabalho realizado no m\u00e9todo 1 depende do n\u00famero de oper\u00e1rios que carregam as caixas.<\/b><\/span><\/span><\/span><\/p>\n

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

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

\"\"<\/p>\n

Um corpo que <\/b><\/span><\/span><\/span>voa <\/b><\/span><\/span><\/span>tem seu <\/b><\/span><\/span><\/span>peso\u00a0\"\"\u00a0equilibrado por uma for\u00e7a de sustenta\u00e7\u00e3o <\/b><\/span><\/span><\/span>atuando sobre a <\/b><\/span><\/span><\/span>superf\u00edcie de \u00e1rea A <\/b><\/span><\/span><\/span>das <\/b><\/span><\/span><\/span>suas asas. <\/b><\/span><\/span><\/span><\/p>\n

Para <\/b><\/span><\/span><\/span>v\u00f4os em baixa altitude esta for\u00e7a pode ser calculada pela express\u00e3o<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

onde <\/b><\/span><\/span><\/span>V \u00e9 uma velocidade de v\u00f4o t\u00edpica deste corpo.<\/b><\/span><\/span><\/span><\/p>\n

A <\/b><\/span><\/span><\/span>rela\u00e7\u00e3o P\/A<\/b><\/span><\/span><\/span> para um <\/b><\/span><\/span><\/span>avi\u00e3o de passageiros \u00e9 igual a 7200 N\/m<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sup><\/span> e a <\/b><\/span><\/span><\/span>dist\u00e2ncia b entre as pontas <\/b><\/span><\/span><\/span>das <\/b><\/span><\/span><\/span>asas <\/b><\/span><\/span><\/span>(envergadura) \u00e9 de <\/b><\/span><\/span><\/span>60 m. <\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Admita que a <\/b><\/span><\/span><\/span>raz\u00e3o entre as grandezas P\/A e b \u00e9<\/b><\/span><\/span><\/span> <\/b>aproximadamente a mesma para p\u00e1ssaros e avi\u00f5es.<\/b><\/span><\/span><\/span><\/p>\n

a) Estime a envergadura de um pardal.<\/b><\/span><\/span><\/span><\/p>\n

b) Calcule a sua velocidade de v\u00f4o.<\/b><\/span><\/span><\/span><\/p>\n

c) <\/b><\/span><\/span><\/span>Em um <\/b><\/span><\/span><\/span>experimento verificou-se que o esfor\u00e7o muscular <\/b><\/span><\/span><\/span>de um <\/b><\/span><\/span><\/span>p\u00e1ssaro para voar a 10 m\/s <\/b><\/span><\/span><\/span>acarretava um <\/b><\/span><\/span><\/span>consumo de energia de 3,2 J\/s. <\/b><\/span><\/span><\/span>Considerando que <\/b><\/span><\/span><\/span>25% deste consumo \u00e9 efetivamente <\/b><\/span><\/span><\/span>convertido em <\/b><\/span><\/span><\/span>pot\u00eancia mec\u00e2nica, <\/b><\/span><\/span><\/span>calcule<\/b><\/span><\/span><\/span> <\/b>a <\/b><\/span><\/span><\/span>for\u00e7a de resist\u00eancia oferecida pelo ar durante este v\u00f4o.<\/b><\/span><\/span><\/span><\/p>\n

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

17-(UFRN-RN)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

A <\/b><\/span><\/span><\/span>produ\u00e7\u00e3o de energia proveniente de mar\u00e9, <\/b><\/span><\/span><\/span>sistema <\/b><\/span><\/span><\/span>mar\u00e9-motriz <\/b><\/span><\/span><\/span>(no qual se utiliza o <\/b><\/span><\/span><\/span>fluxo das mar\u00e9s para movimentar uma turbina revers\u00edvel <\/b><\/span><\/span><\/span>capaz de <\/b><\/span><\/span><\/span>converter em energia el\u00e9trica a energia potencial gravitacional da \u00e1gua<\/b><\/span><\/span><\/span>), constitui-se numa <\/b><\/span><\/span><\/span>alternativa<\/b><\/span><\/span><\/span> de <\/b><\/span><\/span><\/span>produ\u00e7\u00e3o de energia <\/b><\/span><\/span><\/span>de baixo <\/b><\/span><\/span><\/span>impacto ambiental. <\/b><\/span><\/span><\/span><\/p>\n

Um <\/b><\/span><\/span><\/span>sistema desse tipo encontra-se em funcionamento na localidade de La Rance, Fran\u00e7a, <\/b><\/span><\/span><\/span>desde 1966, com <\/b><\/span><\/span><\/span>capacidade instalada de 240 megawatts. <\/b><\/span><\/span><\/span><\/p>\n

As <\/b><\/span><\/span><\/span>figuras abaixo mostram, esquematicamente<\/b><\/span><\/span><\/span>, um <\/b><\/span><\/span><\/span>corte transversal <\/b><\/span><\/span><\/span>da <\/b><\/span><\/span><\/span>barragem <\/b><\/span><\/span><\/span>de um sistema <\/b><\/span><\/span><\/span>mar\u00e9-motriz, <\/b><\/span><\/span><\/span>em <\/b><\/span><\/span><\/span>quatro situa\u00e7\u00f5es distintas, evidenciando os n\u00edveis da \u00e1gua<\/b><\/span><\/span><\/span>, nos <\/b><\/span><\/span><\/span>dois lados da represa <\/b><\/span><\/span><\/span>(oceano e rio), em <\/b><\/span><\/span><\/span>fun\u00e7\u00e3o da mar\u00e9. <\/b><\/span><\/span><\/span>As <\/b><\/span><\/span><\/span>duas situa\u00e7\u00f5es que permitem a gera\u00e7\u00e3o de energia el\u00e9trica <\/b><\/span><\/span><\/span>s\u00e3o:<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

18-UNESP-SP)\u00a0<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Um <\/b><\/span><\/span><\/span>praticante de esporte radical, <\/b><\/span><\/span><\/span>amarrado a uma <\/b><\/span><\/span><\/span>corda el\u00e1stica, cai<\/b><\/span><\/span><\/span> de uma <\/b><\/span><\/span><\/span>plataforma, a partir do repouso, <\/b><\/span><\/span><\/span>seguindo uma <\/b><\/span><\/span><\/span>trajet\u00f3ria vertical.<\/b><\/span><\/span><\/span> A <\/b><\/span><\/span><\/span>outra extremidade <\/b><\/span><\/span><\/span>da corda est\u00e1 <\/b><\/span><\/span><\/span>presa na plataforma.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\u00a0A <\/b><\/span><\/span><\/span>figura mostra dois gr\u00e1ficos <\/b><\/span><\/span><\/span>que <\/b><\/span><\/span><\/span>foram tra\u00e7ados desprezando-se o atrito do ar <\/b><\/span><\/span><\/span>em <\/b><\/span><\/span><\/span>toda a trajet\u00f3ria. <\/b><\/span><\/span><\/span>O <\/b><\/span><\/span><\/span>primeiro <\/b><\/span><\/span><\/span>\u00e9 o da <\/b><\/span><\/span><\/span>energia potencial gravitacional, U<\/b><\/span><\/span><\/span>gravitacional<\/b><\/span><\/span><\/sub><\/span>, do <\/b><\/span><\/span><\/span>praticante em fun\u00e7\u00e3o da dist\u00e2ncia y <\/b><\/span><\/span><\/span>entre <\/b><\/span><\/span><\/span>ele e a plataforma, <\/b><\/span><\/span><\/span>onde o <\/b><\/span><\/span><\/span>potencial zero foi escolhido em y = 30 m. <\/b><\/span><\/span><\/span><\/p>\n

Nessa posi\u00e7\u00e3o, o praticante atinge o maior afastamento da plataforma, <\/b><\/span><\/span><\/span>quando sua <\/b><\/span><\/span><\/span>velocidade se reduz, momentaneamente, a zero.<\/b><\/span><\/span><\/span> <\/b><\/p>\n

O <\/b><\/span><\/span><\/span>segundo <\/b><\/span><\/span><\/span>\u00e9 o <\/b><\/span><\/span><\/span>gr\u00e1fico da energia armazenada na corda, U<\/b><\/span><\/span><\/span>el\u00e1stica<\/b><\/span><\/span><\/sub><\/span>, <\/b><\/span><\/span><\/span>em <\/b><\/span><\/span><\/span>fun\u00e7\u00e3o da dist\u00e2ncia <\/b><\/span><\/span><\/span>entre <\/b><\/span><\/span><\/span>suas extremidades.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

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

a) <\/b><\/span><\/span><\/span>o <\/b><\/span><\/span><\/span>peso P do praticante e o comprimento L<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sub><\/span>\u00a0da corda.<\/b><\/span><\/span><\/span><\/p>\n

b) <\/b><\/span><\/span><\/span>a <\/b><\/span><\/span><\/span>constante el\u00e1stica K da corda<\/b><\/span><\/span><\/span><\/p>\n

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

19-(UFG-GO)\u00a0<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Uma das <\/b><\/span><\/span><\/span>competi\u00e7\u00f5es dos X-game s\u00e3o as manobras dos esqueitistas em uma rampa em U.<\/b><\/span><\/span><\/span> <\/b><\/p>\n

Um <\/b><\/span><\/span><\/span>atleta parte do repouso do topo da rampa <\/b><\/span><\/span><\/span>e <\/b><\/span><\/span><\/span>atrav\u00e9s do movimento do seu corpo, de peso 800 N, <\/b><\/span><\/span><\/span>consegue <\/b><\/span><\/span><\/span>ganhar 600 J a cada ida e vinda na rampa, conforme ilustra\u00e7\u00e3o a seguir.<\/b><\/span><\/span><\/span>\"\"<\/p>\n

Desprezando <\/b><\/span><\/span><\/span>as <\/b><\/span><\/span><\/span>perdas de energia <\/b><\/span><\/span><\/span>e o <\/b><\/span><\/span><\/span>peso do skate, <\/b><\/span><\/span><\/span>o <\/b><\/span><\/span><\/span>n\u00famero m\u00ednimo de idas e vindas <\/b><\/span><\/span><\/span>que o <\/b><\/span><\/span><\/span>atleta<\/b><\/span><\/span><\/span> <\/b>deve realizar para atingir uma altura (h) de 3 m acima do topo da rampa <\/b><\/span><\/span><\/span>\u00e9:<\/b><\/span><\/span><\/span><\/p>\n

a) <\/b><\/span><\/span><\/span>2\u00a0 \u00a0\u00a0\u00a0\u00a0\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

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

c) <\/b><\/span><\/span><\/span>4\u00a0 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\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>6\u00a0 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\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\u00a0<\/b><\/span><\/span><\/span><\/p>\n

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

20-(UFAL-AL)\u00a0<\/b><\/span><\/span><\/span><\/p>\n

A <\/b><\/span><\/span><\/span>figura<\/b><\/span><\/span><\/span> mostra um <\/b><\/span><\/span><\/span>bloco de peso 10 N em equil\u00edbrio <\/b><\/span><\/span><\/span>co\"\"ntraindo uma <\/b><\/span><\/span><\/span>mola ideal de constante el\u00e1stica 100 N\/m.<\/b><\/span><\/span><\/span> <\/b><\/p>\n

N\u00e3o existe atrito entre o bloco<\/b><\/span><\/span><\/span> e o <\/b><\/span><\/span><\/span>plano inclinado e sabe-se que sen\u03b8 = 0,8 e cos\u03b8 = 0,6. <\/b><\/span><\/span><\/span><\/p>\n

Considere que a <\/b><\/span><\/span><\/span>energia potencial el\u00e1stica \u00e9 nula <\/b><\/span><\/span><\/span>quando a <\/b><\/span><\/span><\/span>mola n\u00e3o est\u00e1 nem contra\u00edda nem distendida,<\/b><\/span><\/span><\/span> e que a <\/b><\/span><\/span><\/span>energia potencial gravitacional \u00e9 nula no n\u00edvel do ponto P, situado a uma altura de 10 cm acima do centro de massa do bloco.<\/b><\/span><\/span><\/span>\"\"<\/p>\n

Nesse <\/b><\/span><\/span><\/span>contexto,<\/b><\/span><\/span><\/span> pode-se <\/b><\/span><\/span><\/span>afirmar que a soma das energias potenciais el\u00e1stica da mola e gravitacional do bloco na situa\u00e7\u00e3o da figura <\/b><\/span><\/span><\/span>vale:<\/b><\/span><\/span><\/span><\/p>\n

a) <\/b><\/span><\/span><\/span>\u22120,68 J\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

b) <\/b><\/span><\/span><\/span>\u22120,32 J\u00a0 \u00a0\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>zero\u00a0 \u00a0\u00a0\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>0,32 J\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>0,68 J\u00a0<\/b><\/span><\/span><\/span><\/p>\n

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

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

\"\"<\/p>\n

Um <\/b><\/span><\/span><\/span>menino puxa, com uma corda, na dire\u00e7\u00e3o horizontal, <\/b><\/span><\/span><\/span>um <\/b><\/span><\/span><\/span>cachorro de brinquedo <\/b><\/span><\/span><\/span>formado por <\/b><\/span><\/span><\/span>duas partes, A e B, ligadas entre si por uma mola, <\/b><\/span><\/span><\/span>como <\/b><\/span><\/span><\/span>ilustra a figura. <\/b><\/span><\/span><\/span><\/p>\n

As partes A e B t\u00eam, respectivamente, massas m<\/b><\/span><\/span><\/span>A<\/b><\/span><\/span><\/sub><\/span>\u00a0= 0,5 kg <\/b><\/span><\/span><\/span>e <\/b><\/span><\/span><\/span>m<\/b><\/span><\/span><\/span>B<\/b><\/span><\/span><\/sub><\/span>\u00a0= 1 kg, sendo \u03bc<\/b><\/span><\/span><\/span>c<\/b><\/span><\/span><\/sub><\/span>\u00a0= 0,3 <\/b><\/span><\/span><\/span>o <\/b><\/span><\/span><\/span>coeficiente de atrito cin\u00e9tico entre cada parte e o piso. <\/b><\/span><\/span><\/span>\"\"<\/p>\n

A <\/b><\/span><\/span><\/span>constante el\u00e1stica da mola \u00e9 k = 10 N\/m<\/b><\/span><\/span><\/span> e, na <\/b><\/span><\/span><\/span>posi\u00e7\u00e3o relaxada, seu comprimento \u00e9 x<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sub><\/span>\u00a0= 10 cm. <\/b><\/span><\/span><\/span><\/p>\n

O conjunto se move com velocidade constante v = 0,1 m\/s. Nessas condi\u00e7\u00f5es,<\/b><\/span><\/span><\/span> determine:<\/b><\/span><\/span><\/span><\/p>\n

a) <\/b><\/span><\/span><\/span>O <\/b><\/span><\/span><\/span>m\u00f3dulo T da for\u00e7a exercida <\/b><\/span><\/span><\/span>pelo menino <\/b><\/span><\/span><\/span>sobre a parte B.<\/b><\/span><\/span><\/span><\/p>\n

b) <\/b><\/span><\/span><\/span>O <\/b><\/span><\/span><\/span>trabalho W realizado pela for\u00e7a que o menino faz para puxar o brinquedo por 2 minutos.<\/b><\/span><\/span><\/span><\/p>\n

c) <\/b><\/span><\/span><\/span>O <\/b><\/span><\/span><\/span>m\u00f3dulo F da for\u00e7a exercida pela mola sobre a parte A.<\/b><\/span><\/span><\/span><\/p>\n

d) <\/b><\/span><\/span><\/span>O <\/b><\/span><\/span><\/span>comprimento x da mola, com o brinquedo em movimento.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

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

22- (UFPE-PE)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Uma <\/b><\/span><\/span><\/span>crian\u00e7a, <\/b><\/span><\/span><\/span>que est\u00e1 brincando com <\/b><\/span><\/span><\/span>blocos c\u00fabicos id\u00eanticos, constr\u00f3i<\/b><\/span><\/span><\/span> as configura\u00e7\u00f5es <\/b><\/span><\/span><\/span>compostas de tr\u00eas blocos mostradas na figura. <\/b><\/span><\/span><\/span><\/p>\n

Cada bloco tem aresta\u00a0 a = 10 cm e massa\u00a0 M = 100 g.<\/b><\/span><\/span><\/span>\"\"<\/p>\n

A <\/b><\/span><\/span><\/span>crian\u00e7a pode at\u00e9 perceber intuitivamente <\/b><\/span><\/span><\/span>que a <\/b><\/span><\/span><\/span>configura\u00e7\u00e3o A \u00e9 mais est\u00e1vel do que a\u00a0 B, <\/b><\/span><\/span><\/span>mas <\/b><\/span><\/span><\/span>n\u00e3o<\/b><\/span><\/span><\/span> consegue <\/b><\/span><\/span><\/span>quantificar fisicamente essa estabilidade.<\/b><\/span><\/span><\/span><\/p>\n

Para tal, <\/b><\/span><\/span><\/span>\u00e9 necess\u00e1rio determinar a diferen\u00e7a de energia potencial gravitacional \u2206U = U<\/b><\/span><\/span><\/span>B<\/b><\/span><\/span><\/sub><\/span>\u00a0\u2013U<\/b><\/span><\/span><\/span>A<\/b><\/span><\/span><\/sub><\/span>\u00a0<\/b><\/span><\/span><\/span>entre as <\/b><\/span><\/span><\/span>duas configura\u00e7\u00f5es.\u00a0 Qual <\/b><\/span><\/span><\/span>\u00e9 o <\/b><\/span><\/span><\/span>valor de \u2206U, em unidades de <\/b><\/span><\/span><\/span><\/p>\n

10<\/b><\/span><\/span><\/span>-2<\/b><\/span><\/span><\/sup><\/span>\u00a0 joules?<\/b><\/span><\/span><\/span><\/p>\n

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

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

\"\"<\/p>\n

Trens de alta velocidade, <\/b><\/span><\/span><\/span>chamados <\/b><\/span><\/span><\/span>trens-bala, <\/b><\/span><\/span><\/span>dever\u00e3o estar em <\/b><\/span><\/span><\/span>funcionamento no Brasil nos pr\u00f3ximos anos.<\/b><\/span><\/span><\/span><\/p>\n

Caracter\u00edsticas t\u00edpicas desses trens s\u00e3o:<\/b><\/span><\/span><\/span> <\/b>velocidade m\u00e1xima de 300 km\/h, massa total <\/b><\/span><\/span><\/span>(incluindo 500 passageiros) <\/b><\/span><\/span><\/span>de 500 t<\/b><\/span><\/span><\/span> e <\/b><\/span><\/span><\/span>pot\u00eancia m\u00e1xima dos motores el\u00e9tricos igual a 8 MW.<\/b><\/span><\/span><\/span> <\/b>\"\"<\/p>\n

Nesses trens, as m\u00e1quinas el\u00e9tricas <\/b><\/span><\/span><\/span>que atuam como <\/b><\/span><\/span><\/span>motores <\/b><\/span><\/span><\/span>tamb\u00e9m <\/b><\/span><\/span><\/span>podem ser usadas como geradores,<\/b><\/span><\/span><\/span> <\/b>freando o movimento <\/b><\/span><\/span><\/span>(freios regenerativos)<\/b><\/span><\/span><\/span>.<\/b><\/span><\/span><\/span> <\/b><\/p>\n

Nas ferrovias, <\/b><\/span><\/span><\/span>as <\/b><\/span><\/span><\/span>curvas t\u00eam raio de curvatura de, no m\u00ednimo, 5 km. Considerando um trem e uma ferrovia com essas caracter\u00edsticas, <\/b><\/span><\/span><\/span>determine:<\/b><\/span><\/span><\/span><\/p>\n

a) <\/b><\/span><\/span><\/span>O <\/b><\/span><\/span><\/span>tempo necess\u00e1rio<\/b><\/span><\/span><\/span> para o <\/b><\/span><\/span><\/span>trem atingir a velocidade de 288 km\/h, a partir do repouso, <\/b><\/span><\/span><\/span>supondo que os <\/b><\/span><\/span><\/span>motores forne\u00e7am a pot\u00eancia m\u00e1xima o tempo todo.<\/b><\/span><\/span><\/span><\/p>\n

b) <\/b><\/span><\/span><\/span>A <\/b><\/span><\/span><\/span>for\u00e7a m\u00e1xima na dire\u00e7\u00e3o horizontal, <\/b><\/span><\/span><\/span>entre <\/b><\/span><\/span><\/span>cada roda e o trilho, <\/b><\/span><\/span><\/span>numa <\/b><\/span><\/span><\/span>curva horizontal percorrida a 288 km\/h, supondo que o trem tenha 80 rodas e que as for\u00e7as entre cada uma delas e o trilho tenham a mesma intensidade.<\/b><\/span><\/span><\/span><\/p>\n

c) <\/b><\/span><\/span><\/span>A <\/b><\/span><\/span><\/span>acelera\u00e7\u00e3o do trem <\/b><\/span><\/span><\/span>quando, <\/b><\/span><\/span><\/span>na velocidade de 288 km\/h, as m\u00e1quinas el\u00e9tricas s\u00e3o acionadas como geradores de 8 MW de pot\u00eancia, freando o movimento.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

24-(UFMG-MG)\u00a0<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Daniel e Andr\u00e9, <\/b><\/span><\/span><\/span>seu irm\u00e3o, est\u00e3o <\/b><\/span><\/span><\/span>parados em um tobog\u00e3, nas posi\u00e7\u00f5es mostradas nesta figura:<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Daniel tem o dobro do peso de Andr\u00e9<\/b><\/span><\/span><\/span> e a <\/b><\/span><\/span><\/span>altura em que ele est\u00e1, em rela\u00e7\u00e3o ao solo, corresponde \u00e0 metade da altura em que est\u00e1 seu irm\u00e3o.<\/b><\/span><\/span><\/span> <\/b><\/p>\n

Em um <\/b><\/span><\/span><\/span>certo instante, os dois come\u00e7am a escorregar pelo tobog\u00e3. Despreze as for\u00e7as de atrito.<\/b><\/span><\/span><\/span><\/p>\n

\u00c9 <\/b><\/span><\/span><\/span>CORRETO afirmar que, <\/b><\/span><\/span><\/span>nessa situa\u00e7\u00e3o, ao <\/b><\/span><\/span><\/span>atingirem o n\u00edvel do solo, Andr\u00e9 e Daniel ter\u00e3o<\/b><\/span><\/span><\/span><\/p>\n

a) energias cin\u00e9ticas diferentes <\/b><\/span><\/span><\/span>e <\/b><\/span><\/span><\/span>m\u00f3dulos de velocidade diferentes.<\/b><\/span><\/span><\/span><\/p>\n

b) energias cin\u00e9ticas iguais <\/b><\/span><\/span><\/span>e <\/b><\/span><\/span><\/span>m\u00f3dulos de velocidade iguais.<\/b><\/span><\/span><\/span><\/p>\n

c) energias cin\u00e9ticas diferentes <\/b><\/span><\/span><\/span>e <\/b><\/span><\/span><\/span>m\u00f3dulos de velocidade iguais.<\/b><\/span><\/span><\/span><\/p>\n

d) energias cin\u00e9ticas iguais <\/b><\/span><\/span><\/span>e <\/b><\/span><\/span><\/span>m\u00f3dulos de velocidade diferentes.<\/b><\/span><\/span><\/span><\/p>\n

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

25-(MACKENZIE-SP)\u00a0<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

A <\/b><\/span><\/span><\/span>figura mostra o instante <\/b><\/span><\/span><\/span>em que uma <\/b><\/span><\/span><\/span>esfera de 4 kg \u00e9 abandonada do repouso<\/b><\/span><\/span><\/span>, da <\/b><\/span><\/span><\/span>posi\u00e7\u00e3o P,<\/b><\/span><\/span><\/span> e <\/b><\/span><\/span><\/span>cai sobre a mola ideal de constante el\u00e1stica 2.10<\/b><\/span><\/span><\/span>2 <\/b><\/span><\/span><\/sup><\/span>N\/m. <\/b><\/span><\/span><\/span><\/p>\n

O <\/b><\/span><\/span><\/span>maior valor da velocidade atingida por essa esfera, <\/b><\/span><\/span><\/span>no seu <\/b><\/span><\/span><\/span>movimento descendente<\/b><\/span><\/span><\/span>, \u00e9<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

26-(UFG-GO)\u00a0<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

Um <\/b><\/span><\/span><\/span>bloco de massa igual a 0,5 kg \u00e9 abandonado, em repouso, 2 m acima de uma mola vertical de comprimento 0,8 m e constante el\u00e1stica igual a 100 N\/m, conforme o diagrama.<\/b><\/span><\/span><\/span><\/p>\n

Calcule o menor comprimento que a mola atingir\u00e1<\/b><\/span><\/span><\/span>. Considere <\/b><\/span><\/span><\/span>g = 10 m\/s<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sup><\/span>.<\/b><\/span><\/span><\/span><\/p>\n

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

27-(UNIRIO-RJ)<\/b><\/span><\/span><\/span><\/p>\n

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

Um <\/b><\/span><\/span><\/span>carrinho de massa m = 2,0 kg <\/b><\/span><\/span><\/span>apresentado no <\/b><\/span><\/span><\/span>desenho,<\/b><\/span><\/span><\/span> <\/b>desliza <\/b><\/span><\/span><\/span>sobre um <\/b><\/span><\/span><\/span>plano horizontal <\/b><\/span><\/span><\/span>com <\/b><\/span><\/span><\/span>velocidade de 10 m\/s.<\/b><\/span><\/span><\/span> <\/b><\/p>\n

No <\/b><\/span><\/span><\/span>ponto A, <\/b><\/span><\/span><\/span>a <\/b><\/span><\/span><\/span>superf\u00edcie <\/b><\/span><\/span><\/span>passa a <\/b><\/span><\/span><\/span>ser curva, <\/b><\/span><\/span><\/span>com <\/b><\/span><\/span><\/span>raio <\/b><\/span><\/span><\/span>de <\/b><\/span><\/span><\/span>curvatura de 2,0m.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Suponha que o <\/b><\/span><\/span><\/span>atrito seja desprez\u00edvel <\/b><\/span><\/span><\/span>ao longo de <\/b><\/span><\/span><\/span>toda a trajet\u00f3ria\u00a0 <\/b><\/span><\/span><\/span>e que <\/b><\/span><\/span><\/span>g = 10m\/s<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sup><\/span>.<\/b><\/span><\/span><\/span> <\/b>Determine, <\/b><\/span><\/span><\/span>ent\u00e3o:<\/b><\/span><\/span><\/span><\/p>\n

a) <\/b><\/span><\/span><\/span>a <\/b><\/span><\/span><\/span>acelera\u00e7\u00e3o centr\u00edpeta<\/b><\/span><\/span><\/span> no <\/b><\/span><\/span><\/span>ponto B;<\/b><\/span><\/span><\/span><\/p>\n

b) <\/b><\/span><\/span><\/span>a <\/b><\/span><\/span><\/span>rea\u00e7\u00e3o da superf\u00edcie curva <\/b><\/span><\/span><\/span>sobre o <\/b><\/span><\/span><\/span>bloco no ponto C.<\/b><\/span><\/span><\/span><\/p>\n

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

28-(UFSCAR-SP)\u00a0<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Uma <\/b><\/span><\/span><\/span>formiga de massa\u00a0m\u00a0<\/b><\/span><\/span><\/span>encontra-se no <\/b><\/span><\/span><\/span>topo de uma bola de bilhar rigidamente presa <\/b><\/span><\/span><\/span>ao <\/b><\/span><\/span><\/span>solo.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

A <\/b><\/span><\/span><\/span>bola possui raio\u00a0R\u00a0<\/b><\/span><\/span><\/span>e <\/b><\/span><\/span><\/span>superf\u00edcie altamente polida. <\/b><\/span><\/span><\/span><\/p>\n

Considere\u00a0<\/b><\/span><\/span><\/span>g\u00a0a acelera\u00e7\u00e3o da gravidade <\/b><\/span><\/span><\/span>e <\/b><\/span><\/span><\/span>despreze os poss\u00edveis efeitos dissipativos. <\/b><\/span><\/span><\/span><\/p>\n

A <\/b><\/span><\/span><\/span>formiga<\/b><\/span><\/span><\/span> come\u00e7a a <\/b><\/span><\/span><\/span>deslizar na bola com velocidade inicial nula.<\/b><\/span><\/span><\/span><\/p>\n

a)\u00a0 <\/b><\/span><\/span><\/span>Calcule o <\/b><\/span><\/span><\/span>m\u00f3dulo da velocidade da formiga <\/b><\/span><\/span><\/span>no <\/b><\/span><\/span><\/span>ponto em que ela perde contato com a bola.<\/b><\/span><\/span><\/span><\/p>\n

b) <\/b><\/span><\/span><\/span>Calcule a <\/b><\/span><\/span><\/span>altura do solo, em que a formiga perde contato com a bola.<\/b><\/span><\/span><\/span><\/p>\n

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

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

\"\"<\/p>\n

Para <\/b><\/span><\/span><\/span>testar a elasticidade <\/b><\/span><\/span><\/span>de uma <\/b><\/span><\/span><\/span>bola de basquete, <\/b><\/span><\/span><\/span>ela <\/b><\/span><\/span><\/span>\u00e9 solta, <\/b><\/span><\/span><\/span>a partir de <\/b><\/span><\/span><\/span>uma altura H<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sub><\/span>,<\/b><\/span><\/span><\/span> em um <\/b><\/span><\/span><\/span>equipamento no qual seu movimento \u00e9 monitorado por um sensor. <\/b><\/span><\/span><\/span><\/p>\n

Esse <\/b><\/span><\/span><\/span>equipamento registra a altura do centro de massa da bola,<\/b><\/span><\/span><\/span> a <\/b><\/span><\/span><\/span>cada instante, acompanhando<\/b><\/span><\/span><\/span> seus <\/b><\/span><\/span><\/span>sucessivos choques com o ch\u00e3o. <\/b><\/span><\/span><\/span><\/p>\n

A partir da <\/b><\/span><\/span><\/span>an\u00e1lise dos registros, \u00e9 poss\u00edvel,<\/b><\/span><\/span><\/span> ent\u00e3o, <\/b><\/span><\/span><\/span>estimar a elasticidade da bola, <\/b><\/span><\/span><\/span>caracterizada pelo <\/b><\/span><\/span><\/span>coeficiente de restitui\u00e7\u00e3o CR.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

O gr\u00e1fico <\/b><\/span><\/span><\/span>apresenta os registros de alturas, <\/b><\/span><\/span><\/span>em <\/b><\/span><\/span><\/span>fun\u00e7\u00e3o do tempo, <\/b><\/span><\/span><\/span>para uma <\/b><\/span><\/span><\/span>bola de massa M = 0,60kg, <\/b><\/span><\/span><\/span>quando ela <\/b><\/span><\/span><\/span>\u00e9 solta e inicia o movimento com seu centro de massa a uma altura H<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sub><\/span>\u00a0= 1,6m, chocando-se sucessivas vezes com o ch\u00e3o.<\/b><\/span><\/span><\/span> A <\/b><\/span><\/span><\/span>partir dessas informa\u00e7\u00f5es:<\/b><\/span><\/span><\/span><\/p>\n

a) <\/b><\/span><\/span><\/span>Represente, <\/b><\/span><\/span><\/span>no Gr\u00e1fico I da folha de respostas, <\/b><\/span><\/span><\/span>a <\/b><\/span><\/span><\/span>energia potencial da bola, E<\/b><\/span><\/span><\/span>P<\/b><\/span><\/span><\/sub><\/span>,<\/b><\/span><\/span><\/span> em <\/b><\/span><\/span><\/span>joules,<\/b><\/span><\/span><\/span> em <\/b><\/span><\/span><\/span>fun\u00e7\u00e3o do tempo, indicando os valores na escala.<\/b><\/span><\/span><\/span><\/p>\n

b) <\/b><\/span><\/span><\/span>Represente, <\/b><\/span><\/span><\/span>no Gr\u00e1fico II da folha de respostas, <\/b><\/span><\/span><\/span>a <\/b><\/span><\/span><\/span>energia mec\u00e2nica total da bola, E<\/b><\/span><\/span><\/span>T<\/b><\/span><\/span><\/sub><\/span>, em <\/b><\/span><\/span><\/span>joules,<\/b><\/span><\/span><\/span> em <\/b><\/span><\/span><\/span>fun\u00e7\u00e3o do tempo, indicando os valores na escala.<\/b><\/span><\/span><\/span><\/p>\n

c) <\/b><\/span><\/span><\/span>Estime o <\/b><\/span><\/span><\/span>coeficiente de restitui\u00e7\u00e3o CR\u00a0dessa bola, utilizando<\/b><\/span><\/span><\/span> a <\/b><\/span><\/span><\/span>defini\u00e7\u00e3o apresentada abaixo.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

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

30-(UFLA-MG)\u00a0<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Um <\/b><\/span><\/span><\/span>parque aqu\u00e1tico <\/b><\/span><\/span><\/span>tem um <\/b><\/span><\/span><\/span>tobo\u00e1gua,<\/b><\/span><\/span><\/span> conforme a <\/b><\/span><\/span><\/span>figura.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Um <\/b><\/span><\/span><\/span>indiv\u00edduo de 60kg desliza pelo tobo\u00e1gua a partir do ponto A, <\/b><\/span><\/span><\/span>sendo <\/b><\/span><\/span><\/span>lan\u00e7ado numa piscina<\/b><\/span><\/span><\/span> de uma <\/b><\/span><\/span><\/span>altura de 0,8m, ponto B, <\/b><\/span><\/span><\/span>numa <\/b><\/span><\/span><\/span>dire\u00e7\u00e3o que faz um \u00e2ngulo de 30<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sup><\/span>\u00a0com a horizontal.<\/b><\/span><\/span><\/span> Considerando o <\/b><\/span><\/span><\/span>atrito desprez\u00edvel, g = 10 m\/s<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sup><\/span>\u00a0<\/b><\/span><\/span><\/span>e <\/b><\/span><\/span><\/span>cos30<\/b><\/span><\/span><\/span>o <\/b><\/span><\/span><\/sup><\/span>= \u221a3\/2<\/b><\/span><\/span><\/span>,<\/span><\/span><\/span> calcule:<\/b><\/span><\/span><\/span><\/p>\n

a) <\/b><\/span><\/span><\/span>a <\/b><\/span><\/span><\/span>velocidade<\/b><\/span><\/span><\/span> do indiv\u00edduo ao <\/b><\/span><\/span><\/span>deixar o tobo\u00e1gua no ponto B.<\/b><\/span><\/span><\/span><\/p>\n

b) <\/b><\/span><\/span><\/span>a <\/b><\/span><\/span><\/span>energia cin\u00e9tica <\/b><\/span><\/span><\/span>do indiv\u00edduo no <\/b><\/span><\/span><\/span>ponto mais alto da trajet\u00f3ria, ponto C.<\/b><\/span><\/span><\/span><\/p>\n

c) <\/b><\/span><\/span><\/span>a <\/b><\/span><\/span><\/span>altura do ponto C, h<\/b><\/span><\/span><\/span>m\u00e1xima<\/b><\/span><\/span><\/sub><\/span>.<\/b><\/span><\/span><\/span><\/p>\n

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

31-(UNICID-SP)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Para <\/b><\/span><\/span><\/span>acender um cigarro o isqueiro, <\/b><\/span><\/span><\/span>um <\/b><\/span><\/span><\/span>pequeno rolete de a\u00e7o com ranhuras <\/b><\/span><\/span><\/span>em sua <\/b><\/span><\/span><\/span>face encurvada <\/b><\/span><\/span><\/span>\u00e9 <\/b><\/span><\/span><\/span>esfregado contra uma pedra especial, tirando-lhe fa\u00edscas. <\/b><\/span><\/span><\/span><\/p>\n

As <\/b><\/span><\/span><\/span>fa\u00edscas atingem o pavio embebido <\/b><\/span><\/span><\/span>em <\/b><\/span><\/span><\/span>fluido inflam\u00e1vel, ateando-lhe fogo.<\/b><\/span><\/span><\/span>\"\"<\/p>\n

No ato de <\/b><\/span><\/span><\/span>acender seu isqueiro, <\/b><\/span><\/span><\/span>um <\/b><\/span><\/span><\/span>rapaz faz com que o rolete se movimente <\/b><\/span><\/span><\/span>com <\/b><\/span><\/span><\/span>velocidade angular constante,<\/b><\/span><\/span><\/span> aplicando uma <\/b><\/span><\/span><\/span>for\u00e7a tangente ao rolete, de intensidade 1,5 N.<\/b><\/span><\/span><\/span> <\/b><\/p>\n

Depois<\/b><\/span><\/span><\/span> de o rolete <\/b><\/span><\/span><\/span>girar de 1\/4 de volta, <\/b><\/span><\/span><\/span>o <\/b><\/span><\/span><\/span>pavio se incendeia. <\/b><\/span><\/span><\/span><\/p>\n

Sabendo que o <\/b><\/span><\/span><\/span>di\u00e2metro do rolete mede 8 mm, <\/b><\/span><\/span><\/span>pode-se <\/b><\/span><\/span><\/span>inferir que a energia de ativa\u00e7\u00e3o <\/b><\/span><\/span><\/span>empregada para a <\/b><\/span><\/span><\/span>igni\u00e7\u00e3o do fluido, nessa circunst\u00e2ncia,<\/b><\/span><\/span><\/span> seja, em <\/b><\/span><\/span><\/span>joules,<\/b><\/span><\/span><\/span><\/p>\n

Dado: <\/b><\/span><\/span><\/span>\u03c0 = 3,1<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

32-(ITA-SP)\u00a0<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

Um <\/b><\/span><\/span><\/span>aro de1 kg de massa <\/b><\/span><\/span><\/span>encontra-se <\/b><\/span><\/span><\/span>preso a uma mola de massa desprez\u00edvel,<\/b><\/span><\/span><\/span> <\/b>constante el\u00e1stica k = 10 N\/m <\/b><\/span><\/span><\/span>e <\/b><\/span><\/span><\/span>comprimento inicial L = 1 m quando n\u00e3o distendida, afixada no ponto O. <\/b><\/span><\/span><\/span><\/p>\n

A figura mostra o aro numa posi\u00e7\u00e3o P <\/b><\/span><\/span><\/span>em uma <\/b><\/span><\/span><\/span>barra horizontal fixa ao longo da qual o aro pode deslizar sem atrito.<\/b><\/span><\/span><\/span><\/p>\n

Soltando o aro do ponto P, <\/b><\/span><\/span><\/span>qual deve ser sua <\/b><\/span><\/span><\/span>velocidade, em m\/s, ao alcan\u00e7ar o ponto T<\/b><\/span><\/span><\/span>, a <\/b><\/span><\/span><\/span>2 m de dist\u00e2ncia?<\/b><\/span><\/span><\/span><\/p>\n

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

33-(UFF-RJ)\u00a0<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Dois brinquedos id\u00eanticos,<\/b><\/span><\/span><\/span> que <\/b><\/span><\/span><\/span>lan\u00e7am dardos usando molas, <\/b><\/span><\/span><\/span>s\u00e3o <\/b><\/span><\/span><\/span>disparados simultaneamente <\/b><\/span><\/span><\/span>na <\/b><\/span><\/span><\/span>vertical para baixo.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

As <\/b><\/span><\/span><\/span>molas com os respectivos dardos <\/b><\/span><\/span><\/span>foram <\/b><\/span><\/span><\/span>inicialmente comprimidas at\u00e9 a posi\u00e7\u00e3o 1 <\/b><\/span><\/span><\/span>e, ent\u00e3o, <\/b><\/span><\/span><\/span>liberadas.<\/b><\/span><\/span><\/span> <\/b><\/p>\n

A <\/b><\/span><\/span><\/span>\u00fanica diferen\u00e7a entre os dardos I e II, <\/b><\/span><\/span><\/span>conforme <\/b><\/span><\/span><\/span>mostra a figura, <\/b><\/span><\/span><\/span>\u00e9 que <\/b><\/span><\/span><\/span>I tem um peda\u00e7o de chumbo grudado nele, o que n\u00e3o existe em II.<\/b><\/span><\/span><\/span><\/p>\n

Escolha<\/b><\/span><\/span><\/span> o <\/b><\/span><\/span><\/span>gr\u00e1fico<\/b><\/span><\/span><\/span> que representa as <\/b><\/span><\/span><\/span>velocidades dos dardos I e II, <\/b><\/span><\/span><\/span>como <\/b><\/span><\/span><\/span>fun\u00e7\u00e3o do tempo,<\/b><\/span><\/span><\/span> a <\/b><\/span><\/span><\/span>parti<\/b><\/span><\/span><\/span>r do <\/b><\/span><\/span><\/span>instante em que eles saem dos canos dos brinquedos.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

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

34-(FGV-SP)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Em <\/b><\/span><\/span><\/span>algumas esta\u00e7\u00f5es de trem, h\u00e1 r\u00edgidas molas <\/b><\/span><\/span><\/span>no <\/b><\/span><\/span><\/span>fim dos trilhos <\/b><\/span><\/span><\/span>com a <\/b><\/span><\/span><\/span>finalidade de amortecer eventual colis\u00e3o de um trem, cujo maquinista n\u00e3o consiga par\u00e1-lo corretamente junto \u00e0 plataforma. <\/b><\/span><\/span><\/span>Certa <\/b><\/span><\/span><\/span>composi\u00e7\u00e3o, de massa total 2 m, parada bem pr\u00f3xima \u00e0 mola de constante k, relaxada,<\/b><\/span><\/span><\/span> recebe um <\/b><\/span><\/span><\/span>impacto de outra composi\u00e7\u00e3o, de massa m, <\/b><\/span><\/span><\/span>vindo a <\/b><\/span><\/span><\/span>uma velocidade v, que acaba engatando na primeira.<\/b><\/span><\/span><\/span> <\/b>\"\"<\/p>\n

Ambas v\u00e3o comprimir a mola,<\/b><\/span><\/span><\/span> causando-lhe uma <\/b><\/span><\/span><\/span>deforma\u00e7\u00e3o m\u00e1xima x ao pararem<\/b><\/span><\/span><\/span><\/p>\n

instantaneamente,<\/b><\/span><\/span><\/span> como <\/b><\/span><\/span><\/span>mostram os esquemas.<\/b><\/span><\/span><\/span><\/p>\n

Desprezando<\/b><\/span><\/span><\/span> a a\u00e7\u00e3o de <\/b><\/span><\/span><\/span>agentes externos e dissipativos, <\/b><\/span><\/span><\/span>a <\/b><\/span><\/span><\/span>express\u00e3o de x, em fun\u00e7\u00e3o de k, m e v, <\/b><\/span><\/span><\/span>ser\u00e1:\u00a0<\/b><\/span><\/span><\/span><\/p>\n

(A) <\/b><\/span><\/span><\/span><\/span>x = (m.v)\/(3 \u00b7 k).\u00a0\u00a0\u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0\u00a0<\/b><\/span><\/span><\/span><\/span><\/p>\n

(B) <\/b><\/span><\/span><\/span><\/span>x = (m \u00b7 v<\/b><\/span><\/span><\/span><\/span>2<\/b><\/span><\/span><\/span><\/sup><\/span>) \u2215 (3 \u00b7 k).\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/b><\/span><\/span><\/span><\/span><\/p>\n

(C) <\/b><\/span><\/span><\/span><\/span>x = (v \/ 3) \u00b7 \u221a(m\/ k)\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/b><\/span><\/span><\/span><\/span><\/p>\n

(D) <\/b><\/span><\/span><\/span><\/span>x = v \u00b7 \u221a(3\u00b7m) \/ k .\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0\u00a0<\/b><\/span><\/span><\/span><\/span><\/p>\n

(E) <\/b><\/span><\/span><\/span>x = v \u00b7\u221a m\/ (3k).<\/b><\/span><\/span><\/span><\/p>\n

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

\u00a0<\/span>35-(UNIMONTES-MG)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Um <\/b><\/span><\/span><\/span>corpo<\/b><\/span><\/span><\/span> de\u00a0<\/b><\/span><\/span><\/span>massa M\u00a0\u00e9\u00a0abandonado <\/b><\/span><\/span><\/span>de uma <\/b><\/span><\/span><\/span>altura H<\/b><\/span><\/span><\/span>\u00a0e executa um <\/b><\/span><\/span><\/span>movimento de queda livre <\/b><\/span><\/span><\/span>(veja a<\/b><\/span><\/span><\/span><\/p>\n

figura).<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

A <\/b><\/span><\/span><\/span>acelera\u00e7\u00e3o da gravidade no local possui m\u00f3dulo\u00a0g.<\/b><\/span><\/span><\/span><\/p>\n

Desprezando<\/b><\/span><\/span><\/span> a resist\u00eancia do ar, a\u00a0<\/b><\/span><\/span><\/span>altura h, em que o valor da energia cin\u00e9tica \u00e9 3 vezes o da energia potencial, \u00e9 igual a<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

 <\/p>\n

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

Trabalho e Energia Como esse conte\u00fado envolve muita teoria, em caso de d\u00favidas voc\u00ea pode encontr\u00e1-la em fisicaevestibular.com.br \u2013 Mec\u00e2nica. Exerc\u00edcios de vestibulares com resolu\u00e7\u00f5es comentadas sobre Trabalho e Energia 01-(UERJ-RJ)\u00a0 Observe as situa\u00e7\u00f5es a seguir, nas quais um homem desloca uma caixa ao longo de um trajeto AB de 2,5 m. As for\u00e7as e exercidas pelo homem nas duas<\/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-2576","page","type-page","status-publish","hentry"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/2576","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=2576"}],"version-history":[{"count":2,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/2576\/revisions"}],"predecessor-version":[{"id":2581,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/2576\/revisions\/2581"}],"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=2576"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}