{"id":4877,"date":"2020-01-10T03:11:16","date_gmt":"2020-01-10T03:11:16","guid":{"rendered":"http:\/\/fisicaevestibular.com.br\/novo\/?page_id=4877"},"modified":"2024-09-04T14:56:37","modified_gmt":"2024-09-04T14:56:37","slug":"trabalho-e-energia-2018-2019","status":"publish","type":"page","link":"https:\/\/fisicaevestibular.com.br\/novo\/vestibulares-recentes\/mecanica\/trabalho-e-energia-2018-2019\/","title":{"rendered":"Trabalho e Energia 2018\/2019"},"content":{"rendered":"

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

01-(ENEM-MEC-018)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

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Um\u00a0<\/b><\/span><\/span><\/span>projetista<\/b><\/span><\/span><\/span>\u00a0deseja construir um\u00a0<\/b><\/span><\/span><\/span>brinquedo que lance um pequeno cubo ao longo de um trilho horizontal,<\/b><\/span><\/span><\/span>\u00a0e o dispositivo precisa\u00a0<\/b><\/span><\/span><\/span>oferecer a op\u00e7\u00e3o de mudar a velocidade de lan\u00e7amento.\u00a0<\/b><\/span><\/span><\/span>Para isso, ele\u00a0<\/b><\/span><\/span><\/span>utiliza uma mola e um trilho onde o atrito pode ser desprezado\u00a0<\/b><\/span><\/span><\/span>conforme a figura<\/b><\/span><\/span><\/span>.<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

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Para que a\u00a0<\/b><\/span><\/span><\/span>velocidade de lan\u00e7amento do cubo seja aumentada quatro vezes,<\/b><\/span><\/span><\/span>\u00a0o projetista deve<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

(A)\u00a0<\/b><\/span><\/span><\/span>manter a mesma mola e aumentar duas vezes a sua deforma\u00e7\u00e3o.<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

(B)\u00a0<\/b><\/span><\/span><\/span>manter a mesma mola e aumentar quatro vezes a sua deforma\u00e7\u00e3o.<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

(C)\u00a0<\/b><\/span><\/span><\/span>manter a mesma mola e aumentar dezesseis vezes a sua deforma\u00e7\u00e3o.<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

(D)\u00a0<\/b><\/span><\/span><\/span>trocar a mola por outra de constante el\u00e1stica duas vezes maior e manter a deforma\u00e7\u00e3o.<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

(E)\u00a0<\/b><\/span><\/span><\/span>trocar a mola por outra de constante el\u00e1stica quatro vezes maior e manter a deforma\u00e7\u00e3o.<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

02-(Faculdade de Ci\u00eancias M\u00e9dicas da Santa Casa de S\u00e3o Paulo \u2013 SP \u2013 019)<\/b><\/span><\/span><\/span><\/p>\n

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03-(PUC-SP-019)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

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Duas bolas s\u00e3o abandonadas simultaneamente de uma mesma altura,<\/b><\/span><\/span><\/span>\u00a0conforme\u00a0<\/b><\/span><\/span><\/span>representado na figura.<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

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A\u00a0<\/b><\/span><\/span><\/span>massa da bola 1 \u00e9 de 600g\u00a0<\/b><\/span><\/span><\/span>e a\u00a0<\/b><\/span><\/span><\/span>da bola 2 \u00e9 de 250g.\u00a0<\/b><\/span><\/span><\/span>Como\u00a0<\/b><\/span><\/span><\/span>possuem materiais diferentes,<\/b><\/span><\/span><\/span>\u00a0ao\u00a0<\/b><\/span><\/span><\/span>colidirem com o solo, a bola 1 sofre uma perda de 25% de sua energia mec\u00e2nica inicial, enquanto a bola 2 sofre uma perda de 5%. Desprezando a resist\u00eancia do ar, determine, em fun\u00e7\u00e3o de H,\u00a0<\/b><\/span><\/span><\/span>a<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

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diferen\u00e7a entre as alturas m\u00e1ximas alcan\u00e7adas por essas bolas, ap\u00f3s colidirem com o solo.\u00a0<\/b><\/span><\/span><\/span>Adote\u00a0<\/b><\/span><\/span><\/span>como refer\u00eancia as bases das bolas e considere g = 10m\/s\u00b2.<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

A)\u00a0<\/b><\/span><\/span><\/span>0,20H\u00a0<\/b><\/span><\/span><\/span>B)\u00a0<\/b><\/span><\/span><\/span>0,25H\u00a0<\/b><\/span><\/span><\/span>C)\u00a0<\/b><\/span><\/span><\/span>0,50H\u00a0<\/b><\/span><\/span><\/span>D)\u00a0<\/b><\/span><\/span><\/span>0,75H<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

04-(ENEM-MEC-017)<\/b><\/span><\/span><\/span><\/p>\n

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05-(FUVEST-SP-018)<\/b><\/span><\/span><\/span><\/p>\n

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O\u00a0<\/b><\/span><\/span><\/span>projeto\u00a0<\/b><\/span><\/span><\/span>para um\u00a0<\/b><\/span><\/span><\/span>balan\u00e7o de corda \u00fanica\u00a0<\/b><\/span><\/span><\/span>de um\u00a0<\/b><\/span><\/span><\/span>parque de divers\u00f5es\u00a0<\/b><\/span><\/span><\/span>exige que a\u00a0<\/b><\/span><\/span><\/span>corda do brinquedo tenha um comprimento de 2,0 m.<\/b><\/span><\/span><\/span><\/p>\n

O\u00a0<\/b><\/span><\/span><\/span>projetista\u00a0<\/b><\/span><\/span><\/span>tem que\u00a0<\/b><\/span><\/span><\/span>escolher a corda adequada para o balan\u00e7o,<\/b><\/span><\/span><\/span>\u00a0a partir de\u00a0<\/b><\/span><\/span><\/span>cinco ofertas dispon\u00edveis\u00a0<\/b><\/span><\/span><\/span>no mercado,\u00a0<\/b><\/span><\/span><\/span>cada uma delas com distintas tens\u00f5es de ruptura.\u00a0<\/b><\/span><\/span><\/span>A\u00a0<\/b><\/span><\/span><\/span>tabela apresenta essas op\u00e7\u00f5es.<\/b><\/span><\/span><\/span><\/p>\n

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Ele\u00a0<\/b><\/span><\/span><\/span>tem\u00a0<\/b><\/span><\/span><\/span>tamb\u00e9m que incluir no projeto\u00a0<\/b><\/span><\/span><\/span>uma\u00a0<\/b><\/span><\/span><\/span>margem de seguran\u00e7a;\u00a0<\/b><\/span><\/span><\/span>esse\u00a0<\/b><\/span><\/span><\/span>fator de seguran\u00e7a\u00a0<\/b><\/span><\/span><\/span>\u00e9\u00a0<\/b><\/span><\/span><\/span>tipicamente 7,<\/b><\/span><\/span><\/span>\u00a0ou seja, o\u00a0<\/b><\/span><\/span><\/span>balan\u00e7o dever\u00e1 suportar cargas sete vezes a tens\u00e3o no ponto mais baixo da trajet\u00f3ria.<\/b><\/span><\/span><\/span><\/p>\n

Admitindo que uma\u00a0<\/b><\/span><\/span><\/span>pessoa de 60 kg, ao se balan\u00e7ar, parta do repouso,\u00a0<\/b><\/span><\/span><\/span>de uma\u00a0<\/b><\/span><\/span><\/span>altura de 1,2 m\u00a0<\/b><\/span><\/span><\/span>em rela\u00e7\u00e3o \u00e0\u00a0<\/b><\/span><\/span><\/span>posi\u00e7\u00e3o de equil\u00edbrio do balan\u00e7o,\u00a0<\/b><\/span><\/span><\/span>as\u00a0<\/b><\/span><\/span><\/span>cordas que poderiam ser adequadas para o projeto\u00a0<\/b><\/span><\/span><\/span>s\u00e3o<\/b><\/span><\/span><\/span><\/p>\n

(A)\u00a0<\/b><\/span><\/span><\/span>I, II, III, IV e V.<\/b><\/span><\/span><\/span><\/p>\n

(B)\u00a0<\/b><\/span><\/span><\/span>II, III, IV e V, apenas.<\/b><\/span><\/span><\/span><\/p>\n

(C)\u00a0<\/b><\/span><\/span><\/span>III, IV e V, apenas.<\/b><\/span><\/span><\/span><\/p>\n

(D)\u00a0<\/b><\/span><\/span><\/span>IV e V, apenas.<\/b><\/span><\/span><\/span><\/p>\n

(E)\u00a0<\/b><\/span><\/span><\/span>V, apenas.<\/b><\/span><\/span><\/span><\/p>\n

06-(UNESP-SP-018)<\/b><\/span><\/span><\/span><\/p>\n

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07-(UNICAMP-SP-018)<\/b><\/span><\/span><\/span><\/p>\n

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O\u00a0<\/b><\/span><\/span><\/span>primeiro sat\u00e9lite geoestacion\u00e1rio brasileiro<\/b><\/span><\/span><\/span>\u00a0foi\u00a0<\/b><\/span><\/span><\/span>lan\u00e7ado ao espa\u00e7o em 2017\u00a0<\/b><\/span><\/span><\/span>e ser\u00e1<\/b><\/span><\/span><\/span><\/p>\n

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utilizado para comunica\u00e7\u00f5es estrat\u00e9gicas do governo\u00a0<\/b><\/span><\/span><\/span>e na\u00a0<\/b><\/span><\/span><\/span>amplia\u00e7\u00e3o da oferta de comunica\u00e7\u00e3o\u00a0<\/b><\/span><\/span><\/span>de\u00a0<\/b><\/span><\/span><\/span>banda larga.<\/b><\/span><\/span><\/span><\/p>\n

O\u00a0<\/b><\/span><\/span><\/span>foguete que levou o sat\u00e9lite\u00a0<\/b><\/span><\/span><\/span>ao espa\u00e7o foi\u00a0<\/b><\/span><\/span><\/span>lan\u00e7ado\u00a0<\/b><\/span><\/span><\/span>do\u00a0<\/b><\/span><\/span><\/span>Centro Espacial de Kourou,\u00a0<\/b><\/span><\/span><\/span>na\u00a0<\/b><\/span><\/span><\/span>Guiana Francesa.<\/b><\/span><\/span><\/span><\/p>\n

A\u00a0<\/b><\/span><\/span><\/span>massa do sat\u00e9lite \u00e9 constante\u00a0<\/b><\/span><\/span><\/span>desde o\u00a0<\/b><\/span><\/span><\/span>lan\u00e7amento at\u00e9 a entrada em \u00f3rbita\u00a0<\/b><\/span><\/span><\/span>e vale\u00a0<\/b><\/span><\/span><\/span>m = 6,0.103\u00a0kg.<\/b><\/span><\/span><\/span><\/p>\n

O\u00a0<\/b><\/span><\/span><\/span>m\u00f3dulo\u00a0<\/b><\/span><\/span><\/span>de sua\u00a0<\/b><\/span><\/span><\/span>velocidade orbita<\/b><\/span><\/span><\/span>l \u00e9 igual a\u00a0<\/b><\/span><\/span><\/span>3,0 103\u00a0m\/s.<\/b><\/span><\/span><\/span><\/p>\n

Desprezando\u00a0<\/b><\/span><\/span><\/span>a\u00a0<\/b><\/span><\/span><\/span>velocidade inicial do sat\u00e9lite\u00a0<\/b><\/span><\/span><\/span>em\u00a0<\/b><\/span><\/span><\/span>raz\u00e3o<\/b><\/span><\/span><\/span>\u00a0do\u00a0<\/b><\/span><\/span><\/span>movimento de rota\u00e7\u00e3o da Terra,\u00a0<\/b><\/span><\/span><\/span>o\u00a0<\/b><\/span><\/span><\/span>trabalho\u00a0<\/b><\/span><\/span><\/span>da\u00a0<\/b><\/span><\/span><\/span>for\u00e7a resultante sobre o sat\u00e9lite\u00a0<\/b><\/span><\/span><\/span>para\u00a0<\/b><\/span><\/span><\/span>lev\u00e1-lo at\u00e9 a sua \u00f3rbita\u00a0<\/b><\/span><\/span><\/span>\u00e9 igual a<\/b><\/span><\/span><\/span><\/p>\n

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08-(CEDERJ-RJ-2018)<\/b><\/span><\/span><\/span><\/p>\n

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A\u00a0<\/b><\/span><\/span><\/span>figura ilustra\u00a0<\/b><\/span><\/span><\/span>uma\u00a0<\/b><\/span><\/span><\/span>rampa contendo dois trechos horizontais paralelos separados<\/b><\/span><\/span><\/span>\u00a0por uma\u00a0<\/b><\/span><\/span><\/span>dist\u00e2ncia vertical h = 0,15m.<\/b><\/span><\/span><\/span><\/p>\n

Um\u00a0<\/b><\/span><\/span><\/span>disco de a\u00e7o \u00e9 lan\u00e7ado sobre a superf\u00edcie horizontal mais baixa\u00a0<\/b><\/span><\/span><\/span>com uma\u00a0<\/b><\/span><\/span><\/span>velocidade horizontal\u00a0<\/b><\/span><\/span><\/span>de m\u00f3dulo\u00a0<\/b><\/span><\/span><\/span>v0\u00a0= 2,0m\/s.<\/b><\/span><\/span><\/span><\/p>\n

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Considere que a\u00a0<\/b><\/span><\/span><\/span>acelera\u00e7\u00e3o da gravidade\u00a0<\/b><\/span><\/span><\/span>no local \u00e9 aproximadamente\u00a0<\/b><\/span><\/span><\/span>10m\/s2<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>e\u00a0<\/b><\/span><\/span><\/span>despreze as for\u00e7as de atrito.\u00a0<\/b><\/span><\/span><\/span>O\u00a0<\/b><\/span><\/span><\/span>m\u00f3dulo da velocidade\u00a0<\/b><\/span><\/span><\/span>com que o\u00a0<\/b><\/span><\/span><\/span>disco atinge a superf\u00edcie horizontal mais alta\u00a0<\/b><\/span><\/span><\/span>\u00e9<\/b><\/span><\/span><\/span><\/p>\n

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09-(UERJ-RJ\/018)<\/b><\/span><\/span><\/span><\/p>\n

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10-(UERJ-RJ\/018)<\/b><\/span><\/span><\/span><\/p>\n

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O\u00a0<\/b><\/span><\/span><\/span>gr\u00e1fico<\/b><\/span><\/span><\/span>\u00a0a seguir\u00a0<\/b><\/span><\/span><\/span>indica a varia\u00e7\u00e3o da for\u00e7a resultante F\u00a0<\/b><\/span><\/span><\/span>que\u00a0<\/b><\/span><\/span><\/span>atua em um objeto de massa m,\u00a0<\/b><\/span><\/span><\/span>em<\/b><\/span><\/span><\/span><\/p>\n

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uma\u00a0<\/b><\/span><\/span><\/span>trajet\u00f3ria retil\u00ednea\u00a0<\/b><\/span><\/span><\/span>ao longo de um\u00a0<\/b><\/span><\/span><\/span>deslocamento de 12 m.<\/b><\/span><\/span><\/span><\/p>\n

Calcule o\u00a0<\/b><\/span><\/span><\/span>trabalho, em joules, realizado por F\u00a0<\/b><\/span><\/span><\/span>nesse\u00a0<\/b><\/span><\/span><\/span>deslocamento.<\/b><\/span><\/span><\/span><\/p>\n

11-(UFPR-PR-018)<\/b><\/span><\/span><\/span><\/p>\n

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Numa\u00a0<\/b><\/span><\/span><\/span>experi\u00eancia realizada em laborat\u00f3rio,\u00a0<\/b><\/span><\/span><\/span>a\u00a0<\/b><\/span><\/span><\/span>posi\u00e7\u00e3o x\u00a0<\/b><\/span><\/span><\/span>de um objeto, cuja\u00a0<\/b><\/span><\/span><\/span>massa \u00e9 constante,\u00a0<\/b><\/span><\/span><\/span>foi<\/b><\/span><\/span><\/span><\/p>\n

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medida em fun\u00e7\u00e3o do tempo t.\u00a0<\/b><\/span><\/span><\/span>Com isso,\u00a0<\/b><\/span><\/span><\/span>construiu-se o gr\u00e1fico acima.<\/b><\/span><\/span><\/span><\/p>\n

Sabe-se que o referencial adotado para\u00a0<\/b><\/span><\/span><\/span>realizar as medidas \u00e9 inercial\u00a0<\/b><\/span><\/span><\/span>e que o\u00a0<\/b><\/span><\/span><\/span>objeto move-se ao longo de uma linha reta.<\/b><\/span><\/span><\/span><\/p>\n

Com\u00a0<\/b><\/span><\/span><\/span>base no gr\u00e1fico,\u00a0<\/b><\/span><\/span><\/span>considere as\u00a0<\/b><\/span><\/span><\/span>seguintes afirmativas:<\/b><\/span><\/span><\/span><\/p>\n

1.\u00a0<\/b><\/span><\/span><\/span>A energia cin\u00e9tica do objeto \u00e9 constante entre os instantes t = 20 e t = 30 s.<\/b><\/span><\/span><\/span><\/p>\n

2.\u00a0<\/b><\/span><\/span><\/span>A for\u00e7a resultante sobre o objeto em t = 15 s \u00e9 nula.<\/b><\/span><\/span><\/span><\/p>\n

3.\u00a0<\/b><\/span><\/span><\/span>O deslocamento total do objeto desde t = 0 at\u00e9 t = 40 s \u00e9 nulo.<\/b><\/span><\/span><\/span><\/p>\n

Assinale a alternativa correta.<\/b><\/span><\/span><\/span><\/p>\n

a)\u00a0<\/b><\/span><\/span><\/span>Somente a afirmativa 1 \u00e9 verdadeira.<\/b><\/span><\/span><\/span><\/p>\n

b)\u00a0<\/b><\/span><\/span><\/span>Somente as afirmativas 1 e 2 s\u00e3o verdadeiras.<\/b><\/span><\/span><\/span><\/p>\n

c)\u00a0<\/b><\/span><\/span><\/span>Somente as afirmativas 1 e 3 s\u00e3o verdadeiras.<\/b><\/span><\/span><\/span><\/p>\n

d)\u00a0<\/b><\/span><\/span><\/span>Somente as afirmativas 2 e 3 s\u00e3o verdadeiras.<\/b><\/span><\/span><\/span><\/p>\n

e)\u00a0<\/b><\/span><\/span><\/span>As afirmativas 1, 2 e 3 s\u00e3o verdadeiras<\/b><\/span><\/span><\/span><\/p>\n

12-(UECE-CE-018)<\/b><\/span><\/span><\/span><\/p>\n

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Considere uma\u00a0<\/b><\/span><\/span><\/span>locomotiva puxando vag\u00f5es sobre trilhos.<\/b><\/span><\/span><\/span><\/p>\n

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Em um\u00a0<\/b><\/span><\/span><\/span>primeiro trecho da viagem,<\/b><\/span><\/span><\/span>\u00a0\u00e9\u00a0<\/b><\/span><\/span><\/span>aplicada uma for\u00e7a de 1 kN aos vag\u00f5es,\u00a0<\/b><\/span><\/span><\/span>que se\u00a0<\/b><\/span><\/span><\/span>deslocam a 10 m\/s.<\/b><\/span><\/span><\/span><\/p>\n

No\u00a0<\/b><\/span><\/span><\/span>trecho seguinte, \u00e9 aplicada uma for\u00e7a de 2 kN e a velocidade \u00e9 5 m\/s.<\/b><\/span><\/span><\/span><\/p>\n

A\u00a0<\/b><\/span><\/span><\/span>raz\u00e3o entre a pot\u00eancia\u00a0<\/b><\/span><\/span><\/span>no\u00a0<\/b><\/span><\/span><\/span>trecho inicial e no segundo trecho\u00a0<\/b><\/span><\/span><\/span>\u00e9<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n","protected":false},"excerpt":{"rendered":"

Trabalho e Energia 01-(ENEM-MEC-018) Um\u00a0projetista\u00a0deseja construir um\u00a0brinquedo que lance um pequeno cubo ao longo de um trilho horizontal,\u00a0e o dispositivo precisa\u00a0oferecer a op\u00e7\u00e3o de mudar a velocidade de lan\u00e7amento.\u00a0Para isso, ele\u00a0utiliza uma mola e um trilho onde o atrito pode ser desprezado\u00a0conforme a figura. Para que a\u00a0velocidade de lan\u00e7amento do cubo seja aumentada quatro vezes,\u00a0o projetista deve (A)\u00a0manter a mesma<\/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-4877","page","type-page","status-publish","hentry"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/4877","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=4877"}],"version-history":[{"count":1,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/4877\/revisions"}],"predecessor-version":[{"id":4878,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/4877\/revisions\/4878"}],"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=4877"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}