Todas as questões do ENEM

Uma cerca elétrica foi instalada em um muro onde existe um buraco de forma cilíndrica e fechado na base, conforme representado na figura. Os fios condutores da cerca elétrica estão fixos em ambas as extremidades e esticados sob uma tensão de 80 N. Cada fio tem comprimento igual a 2,0 m e massa de 0,001 kg. Certo dia, alguém tocou no fio da cerca mais próximo do muro e esse fio ficou oscilando em sua frequência fundamental. Essa situação fez com que a coluna de ar no buraco, por ressonância, vibrasse na mesma frequência do fio condutor. As paredes do buraco têm um revestimento adequado, de modo que ele age como um tubo sonoro fechado na base e aberto no topo. Considerando que a velocidade do som no ar seja de 330 m/s e que o ar no buraco oscile no modo fundamental, assinale a alternativa que apresenta corretamente a profundidade do buraco.

Segundo a teoria cinética, um gás é constituído por moléculas que se movimentam desordenadamente no espaço do reservatório onde o gás está armazenado. As colisões das moléculas entre si e com as paredes do reservatório são perfeitamente elásticas. Entre duas colisões sucessivas, as moléculas descrevem um MRU. A energia cinética de translação das moléculas é diretamente proporcional à temperatura do gás. Com base nessas informações, considere as seguintes afirmativas:

1. As moléculas se deslocam todas em trajetórias paralelas entre si.

2. Ao colidir com as paredes do reservatório, a energia cinética das moléculas é conservada.

3. A velocidade de deslocamento das moléculas aumenta se a temperatura do gás for aumentada.

Assinale a alternativa correta.

Um próton movimenta-se em linha reta paralelamente às linhas de força de um campo elétrico uniforme, conforme mostrado na figura. Partindo do repouso no ponto 1 e somente sob ação da força elétrica, ele percorre uma distância de 0,6 m e passa pelo ponto 2. Entre os pontos 1 e 2 há uma diferença de potencial ∆V igual a 32 V.

Considerando a massa do próton igual a 1,6 x 10-27 kg e sua carga igual a 1,6 x 10-19 C, assinale a alternativa que apresenta corretamente a velocidade do próton ao passar pelo ponto 2.

Um engenheiro eletricista, ao projetar a instalação elétrica de uma edificação, deve levar em conta vários fatores, de modo a garantir principalmente a segurança dos futuros usuários. Considerando um trecho da fiação, com determinado comprimento, que irá alimentar um conjunto de lâmpadas, avalie as seguintes afirmativas:

1. Quanto mais fino for o fio condutor, menor será a sua resistência elétrica.

2. Quanto mais fino for o fio condutor, maior será a perda de energia em forma de calor.

3. Quanto mais fino for o fio condutor, maior será a sua resistividade.

Assinale a alternativa correta.

       Jorge Mario Pedro Vargas Llosa, was born on March 28, 1936, in the Peruvian provincial city of Arequipa. He is a writer, politician, journalist, essayist, and Nobel Prize laureate. Vargas Llosa is one of Latin America's most significant novelists and essayists, and one of the leading authors of his generation. Some critics consider him to have had a larger international impact and worldwide audience than any other writer of the Latin American Boom. He was awarded the 2010 Nobel Prize in Literature "for his cartography of structures of power and his trenchant images of the individual's resistance, revolt, and defeat".

Vargas Llosa rose to fame in the 1960s with novels such as The Time of the Hero (La ciudad y los perros, literally The City and the Dogs, 1963/1966), The Green House (La casa verde, 1965/1968), and the monumental Conversation in the Cathedral (Conversación en la catedral, 1969/1975). He writes prolifically across an array of literary genres, including literary criticism and journalism. His novels include comedies, murder mysteries, historical novels, and political thrillers. Several, such as Captain Pantoja and the Special Service (1973/1978) and Aunt Julia and the Scriptwriter (1977/1982), have been adapted as feature films.

      Many of Vargas Llosa's works are influenced by the writer's perception of Peruvian society and his own experiences as a native Peruvian. Increasingly, however, he has expanded his range, and tackled themes that arise from other parts of the world. Another change over the course of his career has been a shift from a style and approach associated with literary modernism, to a sometimes playful postmodernism.

      Like many Latin American authors, Vargas Llosa has been politically active throughout his career; over the course of his life, he has gradually moved from the political left towards liberalism or neoliberalism, a definitively more conservative political position. While he initially supported the Cuban revolutionary government of Fidel Castro, Vargas Llosa later became disenchanted with the Cuban dictator and his authoritarian regime. He ran for the Peruvian presidency in 1990 with the center-right Frente Democrático (FREDEMO) coalition, advocating neoliberal reforms.

(Adapted from www.wikipedia.org) 

       Jorge Mario Pedro Vargas Llosa, was born on March 28, 1936, in the Peruvian provincial city of Arequipa. He is a writer, politician, journalist, essayist, and Nobel Prize laureate. Vargas Llosa is one of Latin America's most significant novelists and essayists, and one of the leading authors of his generation. Some critics consider him to have had a larger international impact and worldwide audience than any other writer of the Latin American Boom. He was awarded the 2010 Nobel Prize in Literature "for his cartography of structures of power and his trenchant images of the individual's resistance, revolt, and defeat".

Vargas Llosa rose to fame in the 1960s with novels such as The Time of the Hero (La ciudad y los perros, literally The City and the Dogs, 1963/1966), The Green House (La casa verde, 1965/1968), and the monumental Conversation in the Cathedral (Conversación en la catedral, 1969/1975). He writes prolifically across an array of literary genres, including literary criticism and journalism. His novels include comedies, murder mysteries, historical novels, and political thrillers. Several, such as Captain Pantoja and the Special Service (1973/1978) and Aunt Julia and the Scriptwriter (1977/1982), have been adapted as feature films.

      Many of Vargas Llosa's works are influenced by the writer's perception of Peruvian society and his own experiences as a native Peruvian. Increasingly, however, he has expanded his range, and tackled themes that arise from other parts of the world. Another change over the course of his career has been a shift from a style and approach associated with literary modernism, to a sometimes playful postmodernism.

      Like many Latin American authors, Vargas Llosa has been politically active throughout his career; over the course of his life, he has gradually moved from the political left towards liberalism or neoliberalism, a definitively more conservative political position. While he initially supported the Cuban revolutionary government of Fidel Castro, Vargas Llosa later became disenchanted with the Cuban dictator and his authoritarian regime. He ran for the Peruvian presidency in 1990 with the center-right Frente Democrático (FREDEMO) coalition, advocating neoliberal reforms.

(Adapted from www.wikipedia.org) 

       Jorge Mario Pedro Vargas Llosa, was born on March 28, 1936, in the Peruvian provincial city of Arequipa. He is a writer, politician, journalist, essayist, and Nobel Prize laureate. Vargas Llosa is one of Latin America's most significant novelists and essayists, and one of the leading authors of his generation. Some critics consider him to have had a larger international impact and worldwide audience than any other writer of the Latin American Boom. He was awarded the 2010 Nobel Prize in Literature "for his cartography of structures of power and his trenchant images of the individual's resistance, revolt, and defeat".

Vargas Llosa rose to fame in the 1960s with novels such as The Time of the Hero (La ciudad y los perros, literally The City and the Dogs, 1963/1966), The Green House (La casa verde, 1965/1968), and the monumental Conversation in the Cathedral (Conversación en la catedral, 1969/1975). He writes prolifically across an array of literary genres, including literary criticism and journalism. His novels include comedies, murder mysteries, historical novels, and political thrillers. Several, such as Captain Pantoja and the Special Service (1973/1978) and Aunt Julia and the Scriptwriter (1977/1982), have been adapted as feature films.

      Many of Vargas Llosa's works are influenced by the writer's perception of Peruvian society and his own experiences as a native Peruvian. Increasingly, however, he has expanded his range, and tackled themes that arise from other parts of the world. Another change over the course of his career has been a shift from a style and approach associated with literary modernism, to a sometimes playful postmodernism.

      Like many Latin American authors, Vargas Llosa has been politically active throughout his career; over the course of his life, he has gradually moved from the political left towards liberalism or neoliberalism, a definitively more conservative political position. While he initially supported the Cuban revolutionary government of Fidel Castro, Vargas Llosa later became disenchanted with the Cuban dictator and his authoritarian regime. He ran for the Peruvian presidency in 1990 with the center-right Frente Democrático (FREDEMO) coalition, advocating neoliberal reforms.

(Adapted from www.wikipedia.org) 

School Curriculum Falls Short on Bigger Lessons

By Tara PARKER-POPE

      Now that children are back in the classroom, are they really learning the lessons that will help them succeed?

      Many child development experts worry that the answer may be no. They say the ever-growing emphasis on academic performance and test scores means many children aren’t developing life skills like self-control, motivation, focus and resilience, which are far better predictors of long-term success than high grades. And it may be distorting their and their parents’ values.

      In one set of studies, children who solved math puzzles were praised for their intelligence or for their hard work. The first group actually did worse on subsequent tests, or took an easy way out, shunning difficult problems. The research suggests that praise for a good effort encourages harder work, while children who are consistently told they are smart do not know what to do when confronted with a difficult problem or reading assignment.

      Academic achievement can certainly help children succeed, and for parents there can be a fine line between praising effort and praising performance. Words need to be chosen carefully: Instead of saying, “I’m so proud you got an ‘A’ on your test”, a better choice is “I’m so proud of you for studying so hard”. Both replies rightly celebrate the ‘A’, but the second focuses on the effort that produced it, encouraging the child to keep trying in the future.

      Praise outside of academics matters, too. Instead of asking your child how many points she scored on the basketball court, say, “Tell me about the game. Did you have fun? Did you play hard?”. Parents also need to teach their children that they do not have to be good at everything, and there is something to be learned when a child struggles or gets a poor grade despite studying hard. One strategy is to teach children that the differences between easy and difficult subjects can provide useful information about their goals and interests. Subjects they enjoy and excel in may become the focus of their careers. Challenging but interesting classes or sports can become hobbies.

(Adapted from www.nyt.com) 

Are these statements TRUE (T) or FALSE (F), according to the text?

( ) Schools tend to emphasize academic performance and test scores.

( ) Students should develop life skills, such as self-control, ambition, and competitiveness.

( ) Getting high grades does not necessarily mean that the student will be successful in life.

( ) The emphasis on academic performance is not supported by parents at all.

( ) Long-term success is usually achieved by students who get high grades.

Mark the alternative which presents the correct sequence, from top to bottom.

School Curriculum Falls Short on Bigger Lessons

By Tara PARKER-POPE

      Now that children are back in the classroom, are they really learning the lessons that will help them succeed?

      Many child development experts worry that the answer may be no. They say the ever-growing emphasis on academic performance and test scores means many children aren’t developing life skills like self-control, motivation, focus and resilience, which are far better predictors of long-term success than high grades. And it may be distorting their and their parents’ values.

      In one set of studies, children who solved math puzzles were praised for their intelligence or for their hard work. The first group actually did worse on subsequent tests, or took an easy way out, shunning difficult problems. The research suggests that praise for a good effort encourages harder work, while children who are consistently told they are smart do not know what to do when confronted with a difficult problem or reading assignment.

      Academic achievement can certainly help children succeed, and for parents there can be a fine line between praising effort and praising performance. Words need to be chosen carefully: Instead of saying, “I’m so proud you got an ‘A’ on your test”, a better choice is “I’m so proud of you for studying so hard”. Both replies rightly celebrate the ‘A’, but the second focuses on the effort that produced it, encouraging the child to keep trying in the future.

      Praise outside of academics matters, too. Instead of asking your child how many points she scored on the basketball court, say, “Tell me about the game. Did you have fun? Did you play hard?”. Parents also need to teach their children that they do not have to be good at everything, and there is something to be learned when a child struggles or gets a poor grade despite studying hard. One strategy is to teach children that the differences between easy and difficult subjects can provide useful information about their goals and interests. Subjects they enjoy and excel in may become the focus of their careers. Challenging but interesting classes or sports can become hobbies.

(Adapted from www.nyt.com)