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Q1384740 Física
O ciclo de combustível nuclear refere-se a todas as atividades que ocorrem na produção de energia nuclear. Sobre o ciclo de combustível nuclear, assinale a alternativa correta.
Alternativas
Q1384739 Física
Suponha que uma amostra pura de um material contendo 1.000 núcleos radioativos seja colocada em uma caixa lacrada. Considere, também, que a meia-vida desse isótopo seja de 59 minutos. Diante do exposto, assinale a alternativa que apresenta, após 3 horas, a quantidade teórica de núcleos radioativos que não sofreram decaimento e, portanto, permanecem na caixa.
Alternativas
Q1384738 Física
Para que o processo de fissão libere grande quantidade de energia, é preciso que ocorra uma reação em cadeia, na qual cada nêutron produzido possa causar uma nova fissão. A reação em cadeia pode ser explosiva ou controlada. Em um reator nuclear, um fator de reprodução k é definido como o número médio de nêutrons resultante de fissões que geram novas fissões. No reator PWR, tanto o moderador quanto as barras de controle têm influência no fator k, mantendo a reação em cadeia controlada. Sobre essa influência, é correto afirmar que
Alternativas
Q1384737 Física

Supondo que ocorra uma transformação radioativa natural em dois estágios de um nuclídeo pai Imagem associada para resolução da questão para um nuclídeo filho Imagem associada para resolução da questão, assinale a alternativa que apresenta os decaimentos que possivelmente ocorreram nos dois estágios para essa transformação.

Alternativas
Q1384736 Física

A história da física nuclear teve início com a descoberta da radioatividade. A radioatividade envolve processos de desintegração espontânea de núcleos atômicos instáveis, sendo que cada tipo de emissão está associado a determinado tipo de estabilidade nuclear. No gráfico abaixo, que representa uma carta de nuclídeos, vê-se a representação de três transições nucleares (X → Y), em que as transformações nucleares convertem um núcleo pai X em um núcleo filho Y . Sobre as transições 1, 2 e 3, indicadas no gráfico Z( × )N , é correto afirmar que elas representam, respectivamente, os seguintes decaimentos:


Imagem associada para resolução da questão

Alternativas
Q1384735 Inglês

NASA’s Nuclear Frontier: The Plum Brook Reactor Facility


    There are three main types of nuclear reactors: power, research, and test. Research and test reactors as scientific tools are more common than most people realize. While power reactors frequently appear in newspaper headlines and are conspicuous because of their size and power, research reactors can be quietly tucked away, even in the midst of a college campus. Power reactors generate heat, which can easily be converted to other useable forms of energy, such as electricity. Research reactors operate at very low thermal power levels – so low, in fact, that they do not even require any type of forced cooling. They are used to measure nuclear parameters and other characteristics, which can then be used to build other reactors or to design experiments for test reactors. Test reactors are more powerful than research reactors and are able to produce much more intense radiation fields. Though they are still much less powerful than the power reactors, they generate enough heat to require a closed-loop forced-circulation coolant system. This system will remove the heat from the reactor by transferring it to a secondary cooling system, which releases it into the atmosphere through cooling towers.

NASA’s Nuclear Frontier: The Plum Brook Reactor Facility. Pages 36 to 40. 

Read the sentence below taken from the text.


Though they are still much less powerful than the power reactors, they generate enough heat to require a closed-loop forced-circulation coolant system.”


Choose the alternative that presents a word or expression that can susbtitute the bold and underlined one above, considering the context and without changing meaning.

Alternativas
Q1384734 Inglês

NASA’s Nuclear Frontier: The Plum Brook Reactor Facility


    There are three main types of nuclear reactors: power, research, and test. Research and test reactors as scientific tools are more common than most people realize. While power reactors frequently appear in newspaper headlines and are conspicuous because of their size and power, research reactors can be quietly tucked away, even in the midst of a college campus. Power reactors generate heat, which can easily be converted to other useable forms of energy, such as electricity. Research reactors operate at very low thermal power levels – so low, in fact, that they do not even require any type of forced cooling. They are used to measure nuclear parameters and other characteristics, which can then be used to build other reactors or to design experiments for test reactors. Test reactors are more powerful than research reactors and are able to produce much more intense radiation fields. Though they are still much less powerful than the power reactors, they generate enough heat to require a closed-loop forced-circulation coolant system. This system will remove the heat from the reactor by transferring it to a secondary cooling system, which releases it into the atmosphere through cooling towers.

NASA’s Nuclear Frontier: The Plum Brook Reactor Facility. Pages 36 to 40. 

Consider the words in bold and underlined in the following excerpts taken from the text.


I. “[...] power reactors frequently appear in newspaper headlines [...]”

II. “[...] research reactors can be quietly tucked away [...]”

III. “[...] which can easily be converted to other useable forms of energy [...]”


Choose the alternative in which the words in bold and underlined have the same grammar classification as the ones above. 

Alternativas
Q1384733 Inglês

NASA’s Nuclear Frontier: The Plum Brook Reactor Facility


    There are three main types of nuclear reactors: power, research, and test. Research and test reactors as scientific tools are more common than most people realize. While power reactors frequently appear in newspaper headlines and are conspicuous because of their size and power, research reactors can be quietly tucked away, even in the midst of a college campus. Power reactors generate heat, which can easily be converted to other useable forms of energy, such as electricity. Research reactors operate at very low thermal power levels – so low, in fact, that they do not even require any type of forced cooling. They are used to measure nuclear parameters and other characteristics, which can then be used to build other reactors or to design experiments for test reactors. Test reactors are more powerful than research reactors and are able to produce much more intense radiation fields. Though they are still much less powerful than the power reactors, they generate enough heat to require a closed-loop forced-circulation coolant system. This system will remove the heat from the reactor by transferring it to a secondary cooling system, which releases it into the atmosphere through cooling towers.

NASA’s Nuclear Frontier: The Plum Brook Reactor Facility. Pages 36 to 40. 

According to the text, the purpose of the closed-loop forced-circulation coolant system is to
Alternativas
Q1384732 Inglês

NASA’s Nuclear Frontier: The Plum Brook Reactor Facility


    There are three main types of nuclear reactors: power, research, and test. Research and test reactors as scientific tools are more common than most people realize. While power reactors frequently appear in newspaper headlines and are conspicuous because of their size and power, research reactors can be quietly tucked away, even in the midst of a college campus. Power reactors generate heat, which can easily be converted to other useable forms of energy, such as electricity. Research reactors operate at very low thermal power levels – so low, in fact, that they do not even require any type of forced cooling. They are used to measure nuclear parameters and other characteristics, which can then be used to build other reactors or to design experiments for test reactors. Test reactors are more powerful than research reactors and are able to produce much more intense radiation fields. Though they are still much less powerful than the power reactors, they generate enough heat to require a closed-loop forced-circulation coolant system. This system will remove the heat from the reactor by transferring it to a secondary cooling system, which releases it into the atmosphere through cooling towers.

NASA’s Nuclear Frontier: The Plum Brook Reactor Facility. Pages 36 to 40. 

According to the text, analyse the assertions below.


I. Power reactors are bigger than research reactors.

II. Research reactors generate more heat than power reactors.

III. Power reactors are more powerful than test or research reactors.


The correct assertion(s) is(are)

Alternativas
Q1384731 Inglês

NASA’s Nuclear Frontier: The Plum Brook Reactor Facility


    There are three main types of nuclear reactors: power, research, and test. Research and test reactors as scientific tools are more common than most people realize. While power reactors frequently appear in newspaper headlines and are conspicuous because of their size and power, research reactors can be quietly tucked away, even in the midst of a college campus. Power reactors generate heat, which can easily be converted to other useable forms of energy, such as electricity. Research reactors operate at very low thermal power levels – so low, in fact, that they do not even require any type of forced cooling. They are used to measure nuclear parameters and other characteristics, which can then be used to build other reactors or to design experiments for test reactors. Test reactors are more powerful than research reactors and are able to produce much more intense radiation fields. Though they are still much less powerful than the power reactors, they generate enough heat to require a closed-loop forced-circulation coolant system. This system will remove the heat from the reactor by transferring it to a secondary cooling system, which releases it into the atmosphere through cooling towers.

NASA’s Nuclear Frontier: The Plum Brook Reactor Facility. Pages 36 to 40. 

Consider the sentence below taken from the text.


  “Power reactors generate heat, which can easily be converted to other useable forms of energy, such as electricity.”


It is correct to affirm that the word in bold and underlined above refers to  

Alternativas
Q1384730 Matemática
Em uma prova com 50 problemas, o aluno ganha 3 pontos para cada problema que acerta e perde 1 ponto para cada problema que erra. Se um aluno obteve 78 pontos e não deixou de resolver nenhum problema, é correto afirmar que a quantidade de acertos dele, nesta prova, foi
Alternativas
Q1384728 Matemática

Um quadrado mágico é uma tabela na qual a soma dos números em cada linha, em cada coluna e na diagonal é sempre a mesma. No quadrado mágico abaixo, dois números foram substituídos pelas letras A e B. Observe.


Imagem associada para resolução da questão


Diante do exposto, assinale a alternativa que apresenta, respectivamente, os valores de A e B, escritos na forma decimal.

Alternativas
Q1384727 Matemática

A soma dos ângulos internos de um triângulo qualquer é igual a 180°. Observe os ângulos internos do triângulo dados na figura abaixo.


Imagem associada para resolução da questão


Diante do exposto, assinale a alternativa que apresenta o valor de x.

Alternativas
Q1384726 Raciocínio Lógico

Cada figura da sequência abaixo apresenta certo número de quadrados pretos e de quadrados brancos. Observe.


Imagem associada para resolução da questão


Assinale a alternativa que apresenta o número de quadrados pretos na próxima figura desta sequência.

Alternativas
Q1384724 Matemática
Uma escada com 14 metros de comprimento está apoiada em um muro. A base da escada está distante do muro cerca de 6 metros. Diante do exposto, assinale a alternativa que apresenta a altura do muro.
Alternativas
Q1384723 Raciocínio Lógico

Considere os conjuntos abaixo e, em seguida, assinale a alternativa correta.


A = { 5,4,3,0 }

B = { 9,8,7,6,5,4,3,2,1 }

Alternativas
Q1384722 Matemática

Quanto às equações de 1º e 2º graus e equações fracionárias, analise as assertivas abaixo.


I. O valor de x na equação 8 + [2x - (4 + 2)2 - 2] = 12 - x(2 - 4)2 é 6.

II. O resultado de x na equação Imagem associada para resolução da questão é 13.

III. A equação x2 − 7x +12 = 0 não tem raízes reais.


É correto o que se afirma em

Alternativas
Q1384721 Matemática

Sobre expressões algébricas, analise as assertivas abaixo.


I. O resultado da expressão (5/6 xy)3 . (5x) é 625/216 n4y3.

II. A expressão algébrica 108x3y –189x2y – 24x + 42 pode ser escrita na seguinte forma: 3(9x2y - 2) . (4x -7) .

III. A forma simplificada da expressão Imagem associada para resolução da questão é 4x - 6.


É correto o que se afirma em

Alternativas
Respostas
1721: C
1722: B
1723: D
1724: E
1725: A
1726: D
1727: C
1728: A
1729: E
1730: A
1731: B
1732: C
1733: D
1734: A
1735: A
1736: E
1737: D
1738: C
1739: B
1740: C