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Considerando o esquema acima, um pesquisador faz três afirmações que se encontram listadas a seguir:
Afirmação I. Se a diferença de pressão entre os dois reservatórios (PA - PB) for equivalente a 20 mm de coluna de água, a variação de massa específica entre os dois fluidos (ρ1 - ρ 2) é igual a 0,2 kg/L.
Afirmação II. Se o Fluido 1 for água e se a diferença de pressão (PA - PB) for de 0,3 kPa, a massa específica do Fluido 2 é igual a 0,7 kg/L.
Afirmação III. Caso o Fluido 1 tenha massa específica igual à metade da massa específica da água, o Fluido 3 (que substitui o Fluido 2 da configuração original) deve ser mais denso do que a água para que a diferença de pressão entre os reservatórios seja a mesma da afirmação I.
Está(ão) correta(s) a(s) afirmação(ões)
Dados:
• massa específica da água: 1 kg/L;
• aceleração da gravidade: 10 m/s2 ;
• Para as afirmações I e II: L1 = 0,30 m e L2 = 0,40 m;
• Para a afirmação III apenas: L1 = 0,60 m e L2 = 0,80 m.
Consideração:
• os fluidos são imiscíveis.

Na Figura 1, o corpo A, constituído de gelo, possui massa m e é solto em uma rampa a uma altura h. Enquanto desliza pela rampa, ele derrete e alcança o plano horizontal com metade da energia mecânica e metade da massa iniciais. Após atingir o plano horizontal, o corpo A se choca, no instante 4T, com o corpo B, de massa m, que foi retirado do repouso através da aplicação da força f(t), cujo gráfico é exibido na Figura 2.
Para que os corpos parem no momento do choque, F deve ser dado por
Dado:
• aceleração da gravidade: g.
Observações:
• o choque entre os corpos é perfeitamente inelástico;
• o corpo não perde massa ao longo de seu movimento no plano horizontal.

A figura acima, cujas cotas estão em metros, exibe uma estrutura em equilíbrio formada por três barras rotuladas AB, BC e CD. Nos pontos B e C existem cargas concentradas verticais. A maior força de tração que ocorre em uma barra, em kN, e a altura h, em metros, da estrutura são
Consideração:
• as barras são rígidas, homogêneas, inextensíveis e de pesos desprezíveis.

Uma partícula de massa m e carga + Q encontra-se confinada no plano XY entre duas lâminas infinitas de vidro, movimentando-se sem atrito com vetor velocidade (v,0,0) no instante t = 0, quando um dispositivo externo passa a gerar um campo magnético dependente do tempo, cujo vetor é (f(t),f(t),B), onde B é uma constante. Pode-se afirmar que a força normal exercida sobre as lâminas é nula quando t é
Consideração:
• desconsidere o efeito gravitacional.

Um corpo de carga positiva, inicialmente em repouso sobre uma rampa plana isolante com atrito, está apoiado em uma mola, comprimindo-a. Após ser liberado, o corpo entra em movimento e atravessa uma região do espaço com diferença de potencial V, sendo acelerado. Para que o corpo chegue ao final da rampa com velocidade nula, a distância d indicada na figura é
Dados:
• deformação inicial da mola comprimida: x;
• massa do corpo: m;
• carga do corpo: + Q;
• aceleração da gravidade: g;
• coeficiente de atrito dinâmico entre o corpo e a rampa: µ;
• ângulo de inclinação da rampa: θ;
• constante elástica da mola: K.
Considerações:
• despreze os efeitos de borda;
• a carga do corpo permanece constante ao longo da trajetória.
What’s in a name?
Henry Louis Gates Jr. (1989)
The question of color takes up much space in these pages, but the question of color, especially in this country, operates to hide the graver questions of the self.
- James Baldwin, 1961
… blood, darky, Tar baby, Kaffir, shine… moor, blackamoor, Jim Crow, spook… quadroon, meriney, red bone, high yellow… Mammy, porch monkey, home, homeboy, George… spearchucker, Leroy, Smokey…mouli, buck, Ethiopian, brother, sistah…
- Trey Ellis, 1989
I had forgotten the incident completely, until I read Trey Elli’s essay, “Remember My Name,” in a recent issue of the Village Voice (June 13, 1989). But there, in the middle of an extended italicized list of the bynames of “the race” (“the race” or “our people” being the terms my parents used in polite or reverential discourse, “jigaboo” or “nigger” more commonly used in anger, jest, or pure disgust), it was: “George”. Now the events of that very brief exchange return to my mind so vividly that I wonder why I had forgotten it.
My father and I were walking home at dusk from his second job. He “moonlighted” as a janitor in the evenings for the telephone company. Every day, but Saturday, he would come home at 3:30 from his regular job at the paper Mill, wash up, eat supper, then at 4:30 head downtown to his second job. He used to make jokes frequently about a union official who moonlighted. I never got the joke, but he and his friends thought it was hilarious. All I knew was that my family always ate well, that my brother and I had new clothes to wear, and that all of the white people in Piedmont, West Virginia, treated my parents with an odd mixture of resentment and respect that even we understood at the time had something directly to do with a small but certain measure of financial security.
He had left a little early that evening because I was with him and I had to be in bed early. I could not have been more than five or six, and we had stopped off at the Cut-Rate Drug Store (where no black person in town but my father could sit down to eat, and eat off real plates with real silverware) so that I could buy some caramel ice cream, two scoops in a wafer cone, please, which I was busy licking when Mr. Wilson walked by.
Mr. Wilson was a very quiet man, whose stony, brooding, silent manner seemed designed to scare off any overtures of friendship, even from white people. He was Irish as was one-third of our village (another third being Italian), the more affluent among whom sent their children to “Catholic School” across the bridge in Maryland. He had white straight hair, like my Uncle Joe, whom he uncannily resembled, and he carried a black worn metal lunch pail, the kind that Riley carried on the television show. My father always spoke to him, and for reasons that we never did understand, he always spoke to my father.
“Hello, Mr. Wilson,” I heard my father say.
“Hello, George.” I stopped licking my ice cream cone, and asked my Dad in a loud voice why Mr. Wilson had called him “George.”
“Doesn’t he know your name, Daddy? Why don’t you tell him your name? Your name isn’t George.”
For a moment I tried to think of who Mr. Wilson was mixing Pop up with. But we didn’t have any Georges among the colored people in Piedmont; nor were there colored Georges living in the neighboring towns and working at the Mill.
“Tell him your name, Daddy.”
“He knows my name, boy,” my father said after a long pause. “He calls all colored people George.” A long silence ensued. It was “one of those things”, as my Mom would put it. Even then, that early, I knew when I was in the presence of “one of those things”, one of those things that provided a glimpse, through a rent curtain, at another world that we could not affect but that affected us. There would be a painful moment of silence, and you would wait for it to give way to a discussion of a black superstar such as Sugar Ray or Jackie Robinson.
“Nobody hits better in a clutch than Jackie Robinson.”
“That’s right. Nobody.”
I never again looked Mr. Wilson in the eye.
What’s in a name?
Henry Louis Gates Jr. (1989)
The question of color takes up much space in these pages, but the question of color, especially in this country, operates to hide the graver questions of the self.
- James Baldwin, 1961
… blood, darky, Tar baby, Kaffir, shine… moor, blackamoor, Jim Crow, spook… quadroon, meriney, red bone, high yellow… Mammy, porch monkey, home, homeboy, George… spearchucker, Leroy, Smokey…mouli, buck, Ethiopian, brother, sistah…
- Trey Ellis, 1989
I had forgotten the incident completely, until I read Trey Elli’s essay, “Remember My Name,” in a recent issue of the Village Voice (June 13, 1989). But there, in the middle of an extended italicized list of the bynames of “the race” (“the race” or “our people” being the terms my parents used in polite or reverential discourse, “jigaboo” or “nigger” more commonly used in anger, jest, or pure disgust), it was: “George”. Now the events of that very brief exchange return to my mind so vividly that I wonder why I had forgotten it.
My father and I were walking home at dusk from his second job. He “moonlighted” as a janitor in the evenings for the telephone company. Every day, but Saturday, he would come home at 3:30 from his regular job at the paper Mill, wash up, eat supper, then at 4:30 head downtown to his second job. He used to make jokes frequently about a union official who moonlighted. I never got the joke, but he and his friends thought it was hilarious. All I knew was that my family always ate well, that my brother and I had new clothes to wear, and that all of the white people in Piedmont, West Virginia, treated my parents with an odd mixture of resentment and respect that even we understood at the time had something directly to do with a small but certain measure of financial security.
He had left a little early that evening because I was with him and I had to be in bed early. I could not have been more than five or six, and we had stopped off at the Cut-Rate Drug Store (where no black person in town but my father could sit down to eat, and eat off real plates with real silverware) so that I could buy some caramel ice cream, two scoops in a wafer cone, please, which I was busy licking when Mr. Wilson walked by.
Mr. Wilson was a very quiet man, whose stony, brooding, silent manner seemed designed to scare off any overtures of friendship, even from white people. He was Irish as was one-third of our village (another third being Italian), the more affluent among whom sent their children to “Catholic School” across the bridge in Maryland. He had white straight hair, like my Uncle Joe, whom he uncannily resembled, and he carried a black worn metal lunch pail, the kind that Riley carried on the television show. My father always spoke to him, and for reasons that we never did understand, he always spoke to my father.
“Hello, Mr. Wilson,” I heard my father say.
“Hello, George.” I stopped licking my ice cream cone, and asked my Dad in a loud voice why Mr. Wilson had called him “George.”
“Doesn’t he know your name, Daddy? Why don’t you tell him your name? Your name isn’t George.”
For a moment I tried to think of who Mr. Wilson was mixing Pop up with. But we didn’t have any Georges among the colored people in Piedmont; nor were there colored Georges living in the neighboring towns and working at the Mill.
“Tell him your name, Daddy.”
“He knows my name, boy,” my father said after a long pause. “He calls all colored people George.” A long silence ensued. It was “one of those things”, as my Mom would put it. Even then, that early, I knew when I was in the presence of “one of those things”, one of those things that provided a glimpse, through a rent curtain, at another world that we could not affect but that affected us. There would be a painful moment of silence, and you would wait for it to give way to a discussion of a black superstar such as Sugar Ray or Jackie Robinson.
“Nobody hits better in a clutch than Jackie Robinson.”
“That’s right. Nobody.”
I never again looked Mr. Wilson in the eye.
1a Etapa: o composto A (C7H6O) sofre oxidação em solução básica de permanganato de potássio. O produto gerado, após neutralizado, é o ácido benzoico;
2a Etapa: o ácido benzoico reage com etanol em solução ácida, produzindo o composto B e água;
3a Etapa: o composto B sofre forte redução com hidreto de lítio-alumínio em éter, gerando dois produtos que, depois de neutralizados, formam então o composto C e o etanol.
Considerando as etapas supracitadas, são feitas as seguintes afirmações:
I) o composto A e o composto C são isômeros.
II) o composto B é um éster.
III) o composto B é o acetato de benzila.
Com base na análise das afirmações acima, assinale a opção correta.