Foram encontradas 50 questões.
- Sistemas Elétricos de PotênciaGeração de EnergiaEnergia Hidrelétrica
- Sistemas Elétricos de PotênciaGeração de EnergiaEnergia Termoelétrica
Considere as afirmações que se seguem, sobre as tendências aparentes que podem ser observadas na geração de energia elétrica no Brasil, a partir de dados disponíveis.
I - É esperado um decrescimento da geração térmica a gás natural, em virtude do aproveitamento do alto poder calorífico do carvão disponível no Brasil.
II - Se a geração a gás natural continuar, durante os próximos 15 anos, sua trajetória de crescimento nos mesmos percentuais anuais apresentados no Balanço Energético Nacional de 2005, a contribuição desse tipo de geração, em 2020, será maior que 50TWh.
III - As restrições ambientais que impedem a construção de novas grandes usinas hidrelétricas não deixam alternativas para o crescimento da geração hidrelétrica no Brasil.
É(São) correta(s) apenas a(s) afirmação(ões):
Provas
Assinale a afirmação que apresenta dados corretos a respeito da geração nuclear no Brasil.
Provas
Considere as afirmações abaixo, que dizem respeito à geração térmica no Brasil.
I - Especificamente acerca das termelétricas a GLP, uma das vantagens da sua implementação no Brasil está relacionada à auto-suficiência nacional nesse tipo de combustível.
II - Segundo o Balanço Energético Nacional de 2005, a geração a gás natural continuou uma trajetória de crescimento no ano de 2004.
III - Uma das principais motivações para a expansão desse tipo de geração é o fato da tecnologia envolvida ser de domínio nacional.
É(São) correta(s) apenas a(s) afirmação(ões):
Provas
Provas
Um circuito RC (Resistor-Capacitor) ligado em série é alimentado por uma fonte de tensão CC. Uma chave on-off, inicialmente desligada, conecta a fonte aos componentes. Estando o capacitor inicialmente descarregado, a partir do instante t=0, quando a chave é ligada, a expressão para o cálculo do tempo consumido até o capacitor se carregar com 20% da tensão da fonte é:
Provas

Para o circuito mostrado na figura, os valores de R, E1 e E2 , respectivamente, são:
Provas
Lança-se uma moeda não tendenciosa até a obtenção da segunda cara. Qual é a probabilidade de a moeda ser lançada cinco vezes?
Provas
Com os dados da tabela abaixo, quanto vale o índice de preços de Laspeyres de 2005 com base (igual a 100) em 2004?
| 2004 |
2005 |
|||
|
Produtos |
Preço corrente | Quantidade | Preço corrente |
Quantidade |
|
Arroz |
5 | 10 | 7 | 5 |
|
Feijão |
8 | 20 | 10 | 25 |
Provas
Books are being scanned to make them searchable
on the Internet. Television broadcasts are being recorded
and archived for online posterity. Radio shows, too, are
getting their digital conversion — to podcasts. With a
few keystrokes, we’ll soon be able to make good use of
much of the world’s knowledge. And we’ll do it from nearly
anywhere — already, newer iPods can carry all your
music, digital photos and TV classics along with more
contemporary prime-time fare.
Will all this instantly accessible information make
us much smarter, or simply more stressed? When can
we stop to think, absorb and evaluate all this data?
“People are already struggling and feeling like they need
to keep up with the variety of information sources they
already have,” said David Greenfield, a psychologist who
wrote Virtual Addiction. “There are upper limits to how
much we can manage.”
It may take better technology to cope with the
problems better technology creates. Of course, if used
properly, the new resources have vast potential to shape
how we live, study and think. Consider books. Nicole
Quaranta, 22, is a typical youth. The New York University
grad student in education does most of her research
online. She’ll check databases for academic journals
and newspaper articles — but rarely books, even though
she admits that an author who spent years on a 300-
page book might have a unique perspective. “The library
is intimidating because I have to go there and everything
is organized by academic area,” Quaranta said. “I don’t
even know where to begin.” Were books as easily
searchable as Web pages, she would reconsider.
Otherwise, they might as well not exist.
With a generation growing up expecting everything
on the Internet, libraries, non-profit organizations and
leading search companies like Yahoo and Microsoft are
committing hundreds of millions of dollars collectively
to scan books and other printed materials so they can
be indexed and retrieved online. […]
Meanwhile, television shows formerly locked up in
network or studio vaults are starting to emerge online.
“Before, once it has been broadcast, it’s gone, and it doesn’t
really contribute to our knowledge space,” said Jakob
Nielsen, a Web design expert with Nielsen Norman Group.
For the past year, Google has been digitally recording
news and other programs from several TV stations in
the San Francisco area. Early next year, America Online
and Warner Bros. will offer free access to dozens of old
television shows, and Apple Computer recently started
selling episodes of shows old and new from ABC and
NBC Universal for .99 each — viewable on computers
and its newer iPods.
In audio, National Public Radio has been producing
free podcasts featuring clips or entire programs. Anyone
with a music player can listen anytime, anywhere.
And then there are materials born digital: Photos
from digital cameras can now be easily shared, even
among strangers, at sites like Yahoo’s Flickr.
Steve Jones, a professor of communications at the
University of Illinois at Chicago, says centralization and
easy access could make people smarter: Instead of
wasting time finding information, they can focus more
on assessing its worth. But there’s the danger, he says,
that people will simply take information for granted:
Assuming that whatever pops up first is the best. Worse,
people may simply tune out.
The key may lie in technologies that push to the
top items you seek. Search analyst Danny Sullivan
describes such a tool as “some sort of metal detector
or magnet to pull all the good stuff out of the haystack.”
Virtual communities may contribute to that end. […]
“Social networks, search engines and things yet
invented are critical as we bring millions of movies, books
and musical recordings online,” said Brewster Kahle, a
search pioneer who created the Internet Archive, a non-
profit preservation group.
Even more important will be good research skills
— infoliteracy, if you will. That means knowing where
and how to look, and evaluating what you get back. […]
By Anick Jesdanun, Associated Press. Dec. 25, 20
There are several ways to avoid the stress caused by instantly accessible information online (lines 58-78), EXCEPT to:
Provas
Books are being scanned to make them searchable
on the Internet. Television broadcasts are being recorded
and archived for online posterity. Radio shows, too, are
getting their digital conversion — to podcasts. With a
few keystrokes, we’ll soon be able to make good use of
much of the world’s knowledge. And we’ll do it from nearly
anywhere — already, newer iPods can carry all your
music, digital photos and TV classics along with more
contemporary prime-time fare.
Will all this instantly accessible information make
us much smarter, or simply more stressed? When can
we stop to think, absorb and evaluate all this data?
“People are already struggling and feeling like they need
to keep up with the variety of information sources they
already have,” said David Greenfield, a psychologist who
wrote Virtual Addiction. “There are upper limits to how
much we can manage.”
It may take better technology to cope with the
problems better technology creates. Of course, if used
properly, the new resources have vast potential to shape
how we live, study and think. Consider books. Nicole
Quaranta, 22, is a typical youth. The New York University
grad student in education does most of her research
online. She’ll check databases for academic journals
and newspaper articles — but rarely books, even though
she admits that an author who spent years on a 300-
page book might have a unique perspective. “The library
is intimidating because I have to go there and everything
is organized by academic area,” Quaranta said. “I don’t
even know where to begin.” Were books as easily
searchable as Web pages, she would reconsider.
Otherwise, they might as well not exist.
With a generation growing up expecting everything
on the Internet, libraries, non-profit organizations and
leading search companies like Yahoo and Microsoft are
committing hundreds of millions of dollars collectively
to scan books and other printed materials so they can
be indexed and retrieved online. […]
Meanwhile, television shows formerly locked up in
network or studio vaults are starting to emerge online.
“Before, once it has been broadcast, it’s gone, and it doesn’t
really contribute to our knowledge space,” said Jakob
Nielsen, a Web design expert with Nielsen Norman Group.
For the past year, Google has been digitally recording
news and other programs from several TV stations in
the San Francisco area. Early next year, America Online
and Warner Bros. will offer free access to dozens of old
television shows, and Apple Computer recently started
selling episodes of shows old and new from ABC and
NBC Universal for .99 each — viewable on computers
and its newer iPods.
In audio, National Public Radio has been producing
free podcasts featuring clips or entire programs. Anyone
with a music player can listen anytime, anywhere.
And then there are materials born digital: Photos
from digital cameras can now be easily shared, even
among strangers, at sites like Yahoo’s Flickr.
Steve Jones, a professor of communications at the
University of Illinois at Chicago, says centralization and
easy access could make people smarter: Instead of
wasting time finding information, they can focus more
on assessing its worth. But there’s the danger, he says,
that people will simply take information for granted:
Assuming that whatever pops up first is the best. Worse,
people may simply tune out.
The key may lie in technologies that push to the
top items you seek. Search analyst Danny Sullivan
describes such a tool as “some sort of metal detector
or magnet to pull all the good stuff out of the haystack.”
Virtual communities may contribute to that end. […]
“Social networks, search engines and things yet
invented are critical as we bring millions of movies, books
and musical recordings online,” said Brewster Kahle, a
search pioneer who created the Internet Archive, a non-
profit preservation group.
Even more important will be good research skills
— infoliteracy, if you will. That means knowing where
and how to look, and evaluating what you get back. […]
By Anick Jesdanun, Associated Press. Dec. 25, 20
In "Virtual communities may contribute to that end." (line 70), the word that could replace may without changing the meaning of the sentence is:
Provas
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