Foram encontradas 50 questões.
Recentemente, a imprensa tem noticiado que o governo pretende aumentar o percentual de etanol anidro na gasolina de 20% para 25%. Considere um tanque de combustível que contenha 60 litros de gasolina com o novo percentual de etanol anidro (25%) e assinale a alternativa que apresenta a massa de sacarose utilizada para produzir o volume de álcool anidro existente no tanque de 60 litros de combustível.
(Considere: 1 mol de sacarose (massa molar = 342 g/mol) produz 4 mols de etanol anidro (massa molar = 46 g/mol) e a densidade do etanol = 0,789 g/cm3.)
Provas
Algumas máscaras de oxigênio, utilizadas em emergências médicas, utilizam KO2 (superóxido de potássio sólido). O KO2 reage com dióxido de carbono e água, ambos em estado gasoso, que são provenientes do ar exalado. Os compostos produzidos nesta reação são o oxigênio molecular gasoso e o carbonato ácido de potássio sólido. Se uma pessoa, que necessita usar a máscara de emergência descrita anteriormente, exala 0,66 g de CO2/min, qual será a massa em gramas de KO2 consumida em 30 min?
(Considere: massas atômicas (g/mol) K = 39,10; O = 16,00; H = 1,01; C = 12,01.)
Provas
Certa quantidade de Fe+3 está contida numa massa de minério de ferro (0,5799 g). Para analisar o teor do ferro nesta amostra usando permanganato de potássio, é necessário que o íon Fe+3 seja reduzido para Fe+2 utilizandose SnCl2. Após este tratamento, e sem nenhuma perda de amostra, sabe-se que a massa do minério foi transferida para um balão volumétrico e seu volume foi completado e aferido em 250 mL utilizando meio clorídrico aquoso. Uma alíquota de 25 mL desta solução de minério foi titulada com permanganato de potássio padronizada e de concentração 3,54 x 10-3 mols/L. Na titulação, gastou-se 26,80 mL de KMnO4. A equação não balanceada está representada a seguir.
\( α \) Fe++ (aq) + b KMnO4 (aq) + c HCl (aq) → d FeCl3 (aq) + e Mn++ (aq) + f KCl (aq)+ g H2O (l)
(Considere: massas molares KMnO4 = 158,04 g/mol; Fe = 55,85 g/mol.)
Assinale os coeficientes estequiométricos a, b, c; a massa de ferro no minério e a percentagem na amostra do minério, respectivamente.
Provas
Para preparar 800 mL de uma solução de HCl 0,75 mol/L, encontra-se disponível a vidraria necessária e uma solução de HCl 36% (m/m) com densidade 1,18 g/cm3. Qual será o volume de solução de HCl 36% (d = 1,18 g/cm3) necessário para produzir 800 mL de HCl 0,75 mol/L?
(Considere: massa molar HCl = 36,46 g/mol.)
Provas
Cerca de 22,6 litros/h de gás carbônico é eliminado pelo corpo de um astronauta. Supondo que todo o gás carbônico liberado pelo astronauta reaja completamente com hidróxido de sódio sólido, a massa de hidróxido de sódio necessária para um dia de viagem, numa nave tripulada por três astronautas com mesma taxa metabólica, será de
(Considere: R = 0,082 L.atm/mol.K; Massas atômicas (g/mol): Na = 22,99; O = 16,00; H = 1,01; C = 12,01; Reação se processa nas CNTP.)
Provas
Science and the olympics: technology's increasing role in the games
People used to rarely associate science with sports, but increased engineering research and investment in technology by professional sporting organizations have merged the two industries, especially in the 2012 London Olympics.
Scientists and engineers played a significant role in shaping the Great Britain Olympic team, according to BBC News. Though the partnership between sports and science has been a relatively new development, the impact of it can be seen across a number of different events.
Mobile technology, smartphones and tablet computers are found in droves at the London Olympics, as coaches, players and country officials can be seen using these devices to gauge and improve their performance.
According to the news outlet, the ease with which these devices can be integrated into sports has been surprising, but the results are hard to ignore.
(http://why.knovel.com/all-engineering-news/1752-science-and-the-olympics-technologys-increasing-role-in-the-games.html – Com adaptações.)
The conjunction highlighted in “Though the partnership between sports and science has been a relatively new development…” could be replaced, without change of meaning, by
Provas
Science and the olympics: technology's increasing role in the games
People used to rarely associate science with sports, but increased engineering research and investment in technology by professional sporting organizations have merged the two industries, especially in the 2012 London Olympics.
Scientists and engineers played a significant role in shaping the Great Britain Olympic team, according to BBC News. Though the partnership between sports and science has been a relatively new development, the impact of it can be seen across a number of different events.
Mobile technology, smartphones and tablet computers are found in droves at the London Olympics, as coaches, players and country officials can be seen using these devices to gauge and improve their performance.
According to the news outlet, the ease with which these devices can be integrated into sports has been surprising, but the results are hard to ignore.
(http://why.knovel.com/all-engineering-news/1752-science-and-the-olympics-technologys-increasing-role-in-the-games.html – Com adaptações.)
The passive voice in “Mobile technology, smartphones and tablet computers are found in droves at the London Olympics” in the active voice is
Provas
Science and the olympics: technology's increasing role in the games
People used to rarely associate science with sports, but increased engineering research and investment in technology by professional sporting organizations have merged the two industries, especially in the 2012 London Olympics.
Scientists and engineers played a significant role in shaping the Great Britain Olympic team, according to BBC News. Though the partnership between sports and science has been a relatively new development, the impact of it can be seen across a number of different events.
Mobile technology, smartphones and tablet computers are found in droves at the London Olympics, as coaches, players and country officials can be seen using these devices to gauge and improve their performance.
According to the news outlet, the ease with which these devices can be integrated into sports has been surprising, but the results are hard to ignore.
(http://why.knovel.com/all-engineering-news/1752-science-and-the-olympics-technologys-increasing-role-in-the-games.html – Com adaptações.)
The main idea of the first paragraph is that
Provas
Mechanical engineers develop an “intelligent co-pilot” for cars
Semiautonomous system takes the wheel to keep drivers safe.
Jennifer Chu, MIT News Office
July 13, 2012
Barrels and cones dot an open field in Saline, Mich., forming an obstacle course for a modified vehicle. A driver remotely steers the vehicle through the course from a nearby location as a researcher looks on. Occasionally, the researcher instructs the driver to keep the wheel straight – a trajectory that appears to put the vehicle on a collision course with a barrel. Despite the driver’s actions, the vehicle steers itself around the obstacle, transitioning control back to the driver once the danger has passed.
The key to the maneuver is a new semiautonomous safety system developed by Sterling Anderson, a PhD student in MIT’s Department of Mechanical Engineering, and Karl Lagnemma, a principal research scientist in MIT’s Robotic Mobility Group.
The system uses an onboard camera and laser rangefinder to identify hazards in a vehicle’s environment. The team devised an algorithm to analyze the data and identify safe zones – avoiding, for example, barrels in a field, or other cars on a roadway. The system allows a driver to control the vehicle, only taking the wheel when the driver is about to exit a safe zone.
Anderson, who has been testing the system in Michigan since last September, describes it as an “intelligent co-pilot” that monitors a driver’s performance and makes behind-the-scenes adjustments to keep the vehicle from colliding with obstacles, or within a safe region of the environment, such as a lane or open area.
“The real innovation is enabling the car to share (control) with you,” Anderson says. “If you want to drive, it’ll just… make sure you don’t hit anything.”
The group presented details of the safety system recently at the Intelligent Vehicles Symposium in Spain.
(http://web.mit.edu/newsoffice/2012/mechanical-engineers-develop-intelligent-car-co-pilot-0713.html – Com adaptações.)
Mark the alternative that presents the correct relation between the fragment and the brackets.
I. “Anderson, who has been testing the system in Michigan since last September, describes it as an ‘intelligent copilot’ that monitors a driver’s performance…” (Anderson)
II. “… the researcher instructs the driver to keep the wheel straight – a trajectory that appears to put the vehicle on a collision course with a barrel.” (trajectory)
III. “Anderson, who has been testing the system in Michigan since last September, describes it as an ‘intelligent copilot’ that monitors a driver’s performance” (co-pilot)
Provas
Mechanical engineers develop an “intelligent co-pilot” for cars
Semiautonomous system takes the wheel to keep drivers safe.
Jennifer Chu, MIT News Office
July 13, 2012
Barrels and cones dot an open field in Saline, Mich., forming an obstacle course for a modified vehicle. A driver remotely steers the vehicle through the course from a nearby location as a researcher looks on. Occasionally, the researcher instructs the driver to keep the wheel straight – a trajectory that appears to put the vehicle on a collision course with a barrel. Despite the driver’s actions, the vehicle steers itself around the obstacle, transitioning control back to the driver once the danger has passed.
The key to the maneuver is a new semiautonomous safety system developed by Sterling Anderson, a PhD student in MIT’s Department of Mechanical Engineering, and Karl Lagnemma, a principal research scientist in MIT’s Robotic Mobility Group.
The system uses an onboard camera and laser rangefinder to identify hazards in a vehicle’s environment. The team devised an algorithm to analyze the data and identify safe zones – avoiding, for example, barrels in a field, or other cars on a roadway. The system allows a driver to control the vehicle, only taking the wheel when the driver is about to exit a safe zone.
Anderson, who has been testing the system in Michigan since last September, describes it as an “intelligent co-pilot” that monitors a driver’s performance and makes behind-the-scenes adjustments to keep the vehicle from colliding with obstacles, or within a safe region of the environment, such as a lane or open area.
“The real innovation is enabling the car to share (control) with you,” Anderson says. “If you want to drive, it’ll just… make sure you don’t hit anything.”
The group presented details of the safety system recently at the Intelligent Vehicles Symposium in Spain.
(http://web.mit.edu/newsoffice/2012/mechanical-engineers-develop-intelligent-car-co-pilot-0713.html – Com adaptações.)
Each verb tense presents verb aspects which reveal what we want to express about the point in time the action takes place. The highlighted verb tense in “The system uses an onboard camera and laser rangefinder…” expresses
Provas
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