Matemática
Matemática
A soma de todos os números inteiros entre 50 e
350 que terminam em 3 é:
Banco de questões
Todas as questões do ENEM
Use os filtros para chegar às questões que interessam. Cada resultado abre em uma página própria com enunciado, alternativas e gabarito.
- 58.062 questões
- 160 instituições
- 23 anos de prova
- Matemática
Matemática
- Matrizes
- Prova de 2015
- CEDERJ
- Dificuldade: Médio
- Com imagem
- Código da questão: 74357EDD-B8
Considere as sentenças:
I O produto das matrizes A =
é a matriz nula de ordem 2.
II O número x = 250.320.530.710 é divisível por 310.III Sendo x e y números reais não nulos, entãoÉ correto afirmar que:
. - Matemática
Matemática
- Geometria Plana
- Prova de 2015
- CEDERJ
- Dificuldade: Médio
- Código da questão: 74410F92-B8
Em um triângulo retângulo, a altura relativa à hipotenusa mede 12 cm, e o menor dos segmentos que ela determina sobre a hipotenusa mede 9 cm. A medida do menor cateto é: - Ciências da Natureza
Química
- Eletroquímica: Oxirredução, Potenciais Padrão de Redução, Pilha, Eletrólise e Leis de Faraday.
- Prova de 2015
- CEDERJ
- Dificuldade: Médio
- Código da questão: 74462FC9-B8
Define-se por eletrólise o processo no qual se induz no sistema, artificial e forçadamente, uma corrente – seja ela elétrica ou química – a fim de se obter uma reação química, convertendo energia elétrica em energia química ou vice-versa. Em resumo, quando dois compostos entram em contato químico, seus elementos são separados, de modo forçado, através da corrente elétrica de energia química.
Em relação à eletrólise, - Ciências da Natureza
Química
- Equilíbrio Químico
- Prova de 2015
- CEDERJ
- Dificuldade: Médio
- Código da questão: 744B2D3E-B8
Considere as condições de remoção de Cl2 , adição de PCl3 e diminuição do volume do recipiente que estão relacionadas com a reaçãoPCl3(g) + Cl2(g) PCl5(g)Sob essas condições, o efeito causado sobre a referida reação é:
- Ciências da Natureza
Química
- Soluções e Substâncias Inorgânicas
- Prova de 2015
- CEDERJ
- Dificuldade: Médio
- Código da questão: 744FC45F-B8
Segundo a teoria eletrolítica de Arrhenius, que considera o comportamento das substâncias quando dissolvidas em água, a função inorgânica dos sais pode ser definida da seguinte forma: Sal é toda substância que, em solução aquosa, sofre dissociação, liberando pelo menos um cátion diferente do H+ ou H3O+ e um aníon diferente do OH- .
O sal formado entre o ácido bórico e o hidróxido de magnésio apresenta a seguinte composição centesimal: - Ciências da Natureza
Química
- Equilíbrio Químico
- Prova de 2015
- CEDERJ
- Dificuldade: Médio
- Código da questão: 74543E28-B8
O efeito íon comum decorre da diminuição da solubilidade de um sal ao se agregar um dos íons. O aumento da concentração de um dos íons que formam o precipitado deve corresponder à diminuição da do outro, para que o Kps permaneça constante, a uma temperatura determinada. Esse efeito é o que permite reduzir a solubilidade de muitos precipitados ou precipitar, quantitativamente, um íon, usando excesso de agente precipitante. O valor do Kps do hidróxido de magnésio é 8.9 x 10-12, a 25.0°C.
A solubilidade desse composto a 25.0°C, em água pura e em uma solução de pH igual a 13.00, será, respectivamente, em molL-1 : - Ciências da Natureza
Química
- Soluções e Substâncias Inorgânicas
- Prova de 2015
- CEDERJ
- Dificuldade: Médio
- Código da questão: 74588C57-B8
Para evitar bolor em armários, utilizam-se produtos denominados “sais secantes", como o CaCl2 anidro, que é higroscópico, isto é, capaz de absorver moléculas de água. Por essa razão, o frasco contendo este secante acaba por acumular líquido no fundo, que nada mais é do que solução aquosa de cloreto de cálcio. Com base nessa informação e utilizando – caso necessário – a tabela periódica, analise as afirmativas a seguir:
I O cloreto de cálcio é um sólido iônico.
II O cloreto de cálcio sólido é um bom condutor de eletricidade.
III Para ser usado como “secante de armário", o sal deve ser higroscópico.
São verdadeiras: - Linguagens
Inglês
- Interpretação de texto | Reading comprehension
- Prova de 2015
- CEDERJ
- Dificuldade: Difícil
- Código da questão: 745D1469-B8
Why don’t we take our own advice?
Oliver Burkeman
“Why is it so hard to take your own advice?” the psychology writer Melissa Dahl asked in a New York magazine essay some months ago, and the question’s been bugging me ever since. I have the arrogance to imagine that if you followed some of the suggestions made each week in this column, you might be a little happier or more productive, with a little less relationship drama, a little more inner calm. (From my email inbox, I know this happens at least occasionally.) But were you to infer from this that I follow such advice flawlessly myself, you’d be mistaken. When friends mention their difficulties with partners or bosses, Dahl wrote, she always tells them to talk to the person involved. Just say something! “And probably, this is good advice,” she mused. “I wouldn’t know, as it’s something I rarely do myself.” I can understand. I suspect most of us can. As the old wisecrack has it: “Take my advice – I’m not using it.”
The cynical take on this is that we ignore our own advice because it’s rubbish: we give it to seem wise, when in fact it’s nonsense. (All advice to “try harder” or “snap out of it” or “look on the bright side” fall into this category: if the recipient could do so, he or she already would have, without your so-called help.)
But a more interesting notion is that the advice is often good – yet something prevents us applying it to ourselves. One such obstacle is simply too much information: inside our own heads, we have access to all manner of details, making us believe that this relationship problem, this job dilemma, is special, so the advice doesn’t apply. Dahl cites work by the psychologist Dan Ariely, showing that when a friend gets a serious medical diagnosis, most people would urge them to get a second opinion. But were it to happen to themselves, they’d be more likely not to do so, for fear of offending their doctor. The fear of offence is something you’d think of only in your own case – and it’s totally unhelpful.
But there’s another big reason I don’t follow my own advice: the huge gulf between grasping something intellectually and really feeling it in your bones. For example, it was years ago that I first encountered the insight that anxiety and insecurity aren’t reduced by trying to exert more control over the world; in fact, that usually makes them worse. I know this. But apparently I have to keep learning it, over and over. Its correctness isn’t sufficient for it to get into my brain once and for all; that takes repeated experience. As a result, I continue to “suddenly realise” things I already wrote an entire book about.
If nothing else, this should be a caution against getting too frustrated with that one friend of yours who keeps getting into the same kind of pickle, time and again, deaf to the obviously good advice that everyone keeps offering. You know the type. We’ve all got a friend like that. The scary thought is that, for some of your friends, it’s probably you.
Adapted from http://www.theguardian.com/lifeandstyle/2015/sep/11/ taking-your-own-advice-oliver-burkeman. Accessed on: 22 out. 2015.
Glossaryadvice: conselho; to bug: incomodar; to infer: concluir; flawlessly: perfeitamente; to muse: meditar; wisecrack: espertinho; cynical: cínico, pessimista; rubbish: besteira; to urge: insistir; gulf: distância; exert: exercer; pickle: encrenca
Diante da confissão da especialista em psicologia Melissa Dahl de que ela própria raramente segue os seus próprios conselhos, o autor do texto, Oliver Burkeman, reage com - Linguagens
Inglês
- Interpretação de texto | Reading comprehension
- Prova de 2015
- CEDERJ
- Dificuldade: Difícil
- Código da questão: 7463BBE7-B8
Why don’t we take our own advice?
Oliver Burkeman
“Why is it so hard to take your own advice?” the psychology writer Melissa Dahl asked in a New York magazine essay some months ago, and the question’s been bugging me ever since. I have the arrogance to imagine that if you followed some of the suggestions made each week in this column, you might be a little happier or more productive, with a little less relationship drama, a little more inner calm. (From my email inbox, I know this happens at least occasionally.) But were you to infer from this that I follow such advice flawlessly myself, you’d be mistaken. When friends mention their difficulties with partners or bosses, Dahl wrote, she always tells them to talk to the person involved. Just say something! “And probably, this is good advice,” she mused. “I wouldn’t know, as it’s something I rarely do myself.” I can understand. I suspect most of us can. As the old wisecrack has it: “Take my advice – I’m not using it.”
The cynical take on this is that we ignore our own advice because it’s rubbish: we give it to seem wise, when in fact it’s nonsense. (All advice to “try harder” or “snap out of it” or “look on the bright side” fall into this category: if the recipient could do so, he or she already would have, without your so-called help.)
But a more interesting notion is that the advice is often good – yet something prevents us applying it to ourselves. One such obstacle is simply too much information: inside our own heads, we have access to all manner of details, making us believe that this relationship problem, this job dilemma, is special, so the advice doesn’t apply. Dahl cites work by the psychologist Dan Ariely, showing that when a friend gets a serious medical diagnosis, most people would urge them to get a second opinion. But were it to happen to themselves, they’d be more likely not to do so, for fear of offending their doctor. The fear of offence is something you’d think of only in your own case – and it’s totally unhelpful.
But there’s another big reason I don’t follow my own advice: the huge gulf between grasping something intellectually and really feeling it in your bones. For example, it was years ago that I first encountered the insight that anxiety and insecurity aren’t reduced by trying to exert more control over the world; in fact, that usually makes them worse. I know this. But apparently I have to keep learning it, over and over. Its correctness isn’t sufficient for it to get into my brain once and for all; that takes repeated experience. As a result, I continue to “suddenly realise” things I already wrote an entire book about.
If nothing else, this should be a caution against getting too frustrated with that one friend of yours who keeps getting into the same kind of pickle, time and again, deaf to the obviously good advice that everyone keeps offering. You know the type. We’ve all got a friend like that. The scary thought is that, for some of your friends, it’s probably you.
Adapted from http://www.theguardian.com/lifeandstyle/2015/sep/11/ taking-your-own-advice-oliver-burkeman. Accessed on: 22 out. 2015.
Glossaryadvice: conselho; to bug: incomodar; to infer: concluir; flawlessly: perfeitamente; to muse: meditar; wisecrack: espertinho; cynical: cínico, pessimista; rubbish: besteira; to urge: insistir; gulf: distância; exert: exercer; pickle: encrenca
Segundo o autor do texto, no terceiro parágrafo, muitas vezes não seguimos o nosso próprio conselho porque - Linguagens
Inglês
- Interpretação de texto | Reading comprehension
- Prova de 2015
- CEDERJ
- Dificuldade: Médio
- Código da questão: 7467ED07-B8
Why don’t we take our own advice?
Oliver Burkeman
“Why is it so hard to take your own advice?” the psychology writer Melissa Dahl asked in a New York magazine essay some months ago, and the question’s been bugging me ever since. I have the arrogance to imagine that if you followed some of the suggestions made each week in this column, you might be a little happier or more productive, with a little less relationship drama, a little more inner calm. (From my email inbox, I know this happens at least occasionally.) But were you to infer from this that I follow such advice flawlessly myself, you’d be mistaken. When friends mention their difficulties with partners or bosses, Dahl wrote, she always tells them to talk to the person involved. Just say something! “And probably, this is good advice,” she mused. “I wouldn’t know, as it’s something I rarely do myself.” I can understand. I suspect most of us can. As the old wisecrack has it: “Take my advice – I’m not using it.”
The cynical take on this is that we ignore our own advice because it’s rubbish: we give it to seem wise, when in fact it’s nonsense. (All advice to “try harder” or “snap out of it” or “look on the bright side” fall into this category: if the recipient could do so, he or she already would have, without your so-called help.)
But a more interesting notion is that the advice is often good – yet something prevents us applying it to ourselves. One such obstacle is simply too much information: inside our own heads, we have access to all manner of details, making us believe that this relationship problem, this job dilemma, is special, so the advice doesn’t apply. Dahl cites work by the psychologist Dan Ariely, showing that when a friend gets a serious medical diagnosis, most people would urge them to get a second opinion. But were it to happen to themselves, they’d be more likely not to do so, for fear of offending their doctor. The fear of offence is something you’d think of only in your own case – and it’s totally unhelpful.
But there’s another big reason I don’t follow my own advice: the huge gulf between grasping something intellectually and really feeling it in your bones. For example, it was years ago that I first encountered the insight that anxiety and insecurity aren’t reduced by trying to exert more control over the world; in fact, that usually makes them worse. I know this. But apparently I have to keep learning it, over and over. Its correctness isn’t sufficient for it to get into my brain once and for all; that takes repeated experience. As a result, I continue to “suddenly realise” things I already wrote an entire book about.
If nothing else, this should be a caution against getting too frustrated with that one friend of yours who keeps getting into the same kind of pickle, time and again, deaf to the obviously good advice that everyone keeps offering. You know the type. We’ve all got a friend like that. The scary thought is that, for some of your friends, it’s probably you.
Adapted from http://www.theguardian.com/lifeandstyle/2015/sep/11/ taking-your-own-advice-oliver-burkeman. Accessed on: 22 out. 2015.
Glossaryadvice: conselho; to bug: incomodar; to infer: concluir; flawlessly: perfeitamente; to muse: meditar; wisecrack: espertinho; cynical: cínico, pessimista; rubbish: besteira; to urge: insistir; gulf: distância; exert: exercer; pickle: encrencaDe acordo com o que autor afirma no quarto parágrafo do texto, a tentativa de controlar o mundo
- Linguagens
Inglês
- Advérbios e conjunções | Adverbs and conjunctions
- Prova de 2015
- CEDERJ
- Dificuldade: Médio
- Código da questão: 746DBD29-B8
Why don’t we take our own advice?
Oliver Burkeman
“Why is it so hard to take your own advice?” the psychology writer Melissa Dahl asked in a New York magazine essay some months ago, and the question’s been bugging me ever since. I have the arrogance to imagine that if you followed some of the suggestions made each week in this column, you might be a little happier or more productive, with a little less relationship drama, a little more inner calm. (From my email inbox, I know this happens at least occasionally.) But were you to infer from this that I follow such advice flawlessly myself, you’d be mistaken. When friends mention their difficulties with partners or bosses, Dahl wrote, she always tells them to talk to the person involved. Just say something! “And probably, this is good advice,” she mused. “I wouldn’t know, as it’s something I rarely do myself.” I can understand. I suspect most of us can. As the old wisecrack has it: “Take my advice – I’m not using it.”
The cynical take on this is that we ignore our own advice because it’s rubbish: we give it to seem wise, when in fact it’s nonsense. (All advice to “try harder” or “snap out of it” or “look on the bright side” fall into this category: if the recipient could do so, he or she already would have, without your so-called help.)
But a more interesting notion is that the advice is often good – yet something prevents us applying it to ourselves. One such obstacle is simply too much information: inside our own heads, we have access to all manner of details, making us believe that this relationship problem, this job dilemma, is special, so the advice doesn’t apply. Dahl cites work by the psychologist Dan Ariely, showing that when a friend gets a serious medical diagnosis, most people would urge them to get a second opinion. But were it to happen to themselves, they’d be more likely not to do so, for fear of offending their doctor. The fear of offence is something you’d think of only in your own case – and it’s totally unhelpful.
But there’s another big reason I don’t follow my own advice: the huge gulf between grasping something intellectually and really feeling it in your bones. For example, it was years ago that I first encountered the insight that anxiety and insecurity aren’t reduced by trying to exert more control over the world; in fact, that usually makes them worse. I know this. But apparently I have to keep learning it, over and over. Its correctness isn’t sufficient for it to get into my brain once and for all; that takes repeated experience. As a result, I continue to “suddenly realise” things I already wrote an entire book about.
If nothing else, this should be a caution against getting too frustrated with that one friend of yours who keeps getting into the same kind of pickle, time and again, deaf to the obviously good advice that everyone keeps offering. You know the type. We’ve all got a friend like that. The scary thought is that, for some of your friends, it’s probably you.
Adapted from http://www.theguardian.com/lifeandstyle/2015/sep/11/ taking-your-own-advice-oliver-burkeman. Accessed on: 22 out. 2015.
Glossaryadvice: conselho; to bug: incomodar; to infer: concluir; flawlessly: perfeitamente; to muse: meditar; wisecrack: espertinho; cynical: cínico, pessimista; rubbish: besteira; to urge: insistir; gulf: distância; exert: exercer; pickle: encrencaIn the second paragraph, in the sentence “we give it to seem wise, when in fact it's nonsense", the conjunction “when" introduces an idea of
- Linguagens
Inglês
- Interpretação de texto | Reading comprehension
- Prova de 2015
- CEDERJ
- Dificuldade: Difícil
- Código da questão: 7474F854-B8
Why don’t we take our own advice?
Oliver Burkeman
“Why is it so hard to take your own advice?” the psychology writer Melissa Dahl asked in a New York magazine essay some months ago, and the question’s been bugging me ever since. I have the arrogance to imagine that if you followed some of the suggestions made each week in this column, you might be a little happier or more productive, with a little less relationship drama, a little more inner calm. (From my email inbox, I know this happens at least occasionally.) But were you to infer from this that I follow such advice flawlessly myself, you’d be mistaken. When friends mention their difficulties with partners or bosses, Dahl wrote, she always tells them to talk to the person involved. Just say something! “And probably, this is good advice,” she mused. “I wouldn’t know, as it’s something I rarely do myself.” I can understand. I suspect most of us can. As the old wisecrack has it: “Take my advice – I’m not using it.”
The cynical take on this is that we ignore our own advice because it’s rubbish: we give it to seem wise, when in fact it’s nonsense. (All advice to “try harder” or “snap out of it” or “look on the bright side” fall into this category: if the recipient could do so, he or she already would have, without your so-called help.)
But a more interesting notion is that the advice is often good – yet something prevents us applying it to ourselves. One such obstacle is simply too much information: inside our own heads, we have access to all manner of details, making us believe that this relationship problem, this job dilemma, is special, so the advice doesn’t apply. Dahl cites work by the psychologist Dan Ariely, showing that when a friend gets a serious medical diagnosis, most people would urge them to get a second opinion. But were it to happen to themselves, they’d be more likely not to do so, for fear of offending their doctor. The fear of offence is something you’d think of only in your own case – and it’s totally unhelpful.
But there’s another big reason I don’t follow my own advice: the huge gulf between grasping something intellectually and really feeling it in your bones. For example, it was years ago that I first encountered the insight that anxiety and insecurity aren’t reduced by trying to exert more control over the world; in fact, that usually makes them worse. I know this. But apparently I have to keep learning it, over and over. Its correctness isn’t sufficient for it to get into my brain once and for all; that takes repeated experience. As a result, I continue to “suddenly realise” things I already wrote an entire book about.
If nothing else, this should be a caution against getting too frustrated with that one friend of yours who keeps getting into the same kind of pickle, time and again, deaf to the obviously good advice that everyone keeps offering. You know the type. We’ve all got a friend like that. The scary thought is that, for some of your friends, it’s probably you.
Adapted from http://www.theguardian.com/lifeandstyle/2015/sep/11/ taking-your-own-advice-oliver-burkeman. Accessed on: 22 out. 2015.
Glossaryadvice: conselho; to bug: incomodar; to infer: concluir; flawlessly: perfeitamente; to muse: meditar; wisecrack: espertinho; cynical: cínico, pessimista; rubbish: besteira; to urge: insistir; gulf: distância; exert: exercer; pickle: encrenca
According to the text, friends who are always in trouble because they do not follow our advice should be treated with - Ciências da Natureza
Física
- Cinemática
- Prova de 2015
- UNICAMP
- Dificuldade: Fácil
- Código da questão: 67E29F3A-19
A demanda por trens de alta velocidade tem crescido em todo o mundo. Uma preocupação importante no projeto desses trens é o conforto dos passageiros durante a aceleração. Sendo assim, considere que, em uma viagem de trem de alta velocidade, a aceleração experimentada pelos passageiros foi limitada a amax = 0,09g, onde g=10 m/s2 é a aceleração da gravidade. Se o trem acelera a partir do repouso com aceleração constante igual a amax, a distância mínima percorrida pelo trem para atingir uma velocidade de 1080 km/h corresponde a - Ciências da Natureza
Física
Um isolamento térmico eficiente é um constante desafio a ser superado para que o homem possa viver em condições extremas de temperatura. Para isso, o entendimento completo dos mecanismos de troca de calor é imprescindível.
Em cada uma das situações descritas a seguir, você deve reconhecer o processo de troca de calor envolvido.
I. As prateleiras de uma geladeira doméstica são grades vazadas, para facilitar fluxo de energia térmica até o congelador por [...]
II. O único processo de troca de calor que pode ocorrer no vácuo é por [...].
III. Em uma garrafa térmica, é mantido vácuo entre as paredes duplas de vidro para evitar que o calor saia ou entre por [....].
Na ordem, os processos de troca de calor utilizados para preencher as lacunas corretamente são:
- Ciências da Natureza
Física
- Dinâmica
- Prova de 2015
- UNICAMP
- Dificuldade: Médio
- Código da questão: 67EE0B06-19
Músculos artificiais feitos de nanotubos de carbono embebidos em cera de parafina podem suportar até duzentas vezes mais peso que um músculo natural do mesmo tamanho. Considere uma fibra de músculo artificial de 1 mm de comprimento, suspensa verticalmente por uma de suas extremidades e com uma massa de 50 gramas pendurada, em repouso, em sua outra extremidade. O trabalho realizado pela fibra sobre a massa, ao se contrair 10%, erguendo a massa até uma nova posição de repouso, é
Se necessário, utilize g = 10 m/s2 .
- Ciências da Natureza
Física
- Ondas e Propriedades Ondulatórias
- Prova de 2015
- UNICAMP
- Dificuldade: Fácil
- Código da questão: 67F85831-19
O Teatro de Luz Negra, típico da República Tcheca, é um tipo de representação cênica caracterizada pelo uso do cenário escuro com uma iluminação estratégica dos objetos exibidos. No entanto, o termo Luz Negra é fisicamente incoerente, pois a coloração negra é justamente a ausência de luz. A luz branca é a composição de luz com vários comprimentos de onda e a cor de um corpo é dada pelo comprimento de onda da luz que ele predominantemente reflete. Assim, um quadro que apresente as cores azul e branca quando iluminado pela luz solar, ao ser iluminado por uma luz monocromática de comprimento de onda correspondente à cor amarela, apresentará, respectivamente, uma coloração - Ciências da Natureza
Física
- Colisão
- Prova de 2015
- UNICAMP
- Dificuldade: Fácil
- Código da questão: 67FF8432-19
Tempestades solares são causadas por um fluxo intenso de partículas de altas energias ejetadas pelo Sol durante erupções solares. Esses jatos de partículas podem transportar bilhões de toneladas de gás eletrizado em altas velocidades, que podem trazer riscos de danos aos satélites em torno da Terra.
Considere que, em uma erupção solar em particular, um conjunto de partículas de massa total mp = 5 kg, deslocando-se com velocidade de módulo vp = 2x105 m/s, choca-se com um satélite de massa Ms = 95 kg que se desloca com velocidade de módulo igual a Vs = 4x103 m/s na mesma direção e em sentido contrário ao das partículas. Se a massa de partículas adere ao satélite após a colisão, o módulo da velocidade final do conjunto será de
- Ciências da Natureza
Física
- Ondas e Propriedades Ondulatórias
- Prova de 2015
- UNICAMP
- Dificuldade: Médio
- Com imagem
- Código da questão: 680B6BA8-19
Um osciloscópio é um instrumento muito útil no estudo da variação temporal dos sinais elétricos em circuitos. No caso de um circuito de corrente alternada, a diferença de potencial (U) e a corrente do circuito (i) variam em função do tempo.
Considere um circuito com dois resistores R1 e R2 em série, alimentados por uma fonte de tensão alternada.
A diferença de potencial nos terminais de cada resistor observada na tela do osciloscópio é representada pelo gráfico abaixo. Analisando o gráfico, pode-se afirmar que a amplitude e a frequência da onda que representa a diferença de potencial nos terminais do resistor de maior resistência são, respectivamente, iguais a
- Ciências da Natureza
Física
- Cinemática
- Prova de 2015
- UNICAMP
- Dificuldade: Fácil
- Com imagem
- Código da questão: 680FDBD9-19
Anemômetros são instrumentos usados para medir a velocidade do vento. A sua construção mais conhecida é a proposta por Robinson em 1846, que consiste em um rotor com quatro conchas hemisféricas presas por hastes, conforme figura abaixo. Em um anemômetro de Robinson ideal, a velocidade do vento é dada pela velocidade linear das conchas. Um anemômetro em que a distância entre as conchas e o centro de rotação é r=25 cm, em um dia cuja velocidade do vento é v=18 km/h, teria uma frequência de rotação de
Se necessário, considere π ≈3.
