Energia mecânica:produção do etanol

Um estudo realizado pela Embrapa Agrobiologia demonstrou que a produção do etanol de cana-de-açúcar tem um balanço energético em torno de 9:1 o que significa que, para cada unidade de energia fóssil consumida durante o processo produtivo, são geradas nove unidades de energia renovável na forma de etanol. Sobre essa energia, é correto afirmar que houve, durante o processo de produção do etanol, 

A questão refere-se ao texto a seguir:

Taking Measure With Hardware and Software

The researchers who founded National Instruments Corp switched from building their own equipment to beefing up other people’s.

“You could start a company.” That offhand comment by Jim Truchard got Jeff Kodosky and Bill Nowlin thinking. Within days, Truchard and his two employees at the Applied Research Laboratories (ARL) at the University of Texas at Austin (UT) decided to give it a go. That was in February 1976. By May, the trio had incorporated. Today, National Instruments Corp has annual Sales topping $425 million, employs more than 3100 people, sells some 1500 hardware and software products, and, for five years running, has been rated by Fortune magazine as one of the 100 best companies to work for.

  At ARL, Truchard headed an underwater acoustic measurements lab. “I had about two dozen different projects, all the way from basic acoustics to pragmatic testing of military sonar beam formers,” he says. Truchard went into science because of Sputnik. “I was right on the cusp of that movement. We were all taking Russian and physics,” he says. He earned bachelor’s and master’s degrees in physics and did his PhD — on a nonlinear parametric acoustic receiving array — in electrical engineering, all at UT. Kodosky and Nowlin both worked part-time for Truchard while enrolled at UT. Nowlin earned a master’s in electrical engineering and Kodosky, who has a bachelor’s in physics from Rensselaer Polytechnic Institute, worked toward a PhD; he drifted between theoretical high-energy physics and computer science but did not complete the degree. (…)

Physics intuition

Both Kodosky and Truchard point to their physics training as playing a role in their success with National Instruments. Says Truchard, “Acoustical measurements are fairly tricky, and it happens to be a smaller area where you didn’t have off-the-shelf equipment. You had to build equipment. That background, and the measurements themselves, created a basis.” What’s more, he adds, “the physics background helps create good intuition. I think having solved differential equations and learned about gradients, you know how things are going to work out. I’ve always felt it helped me develop intuition about business.”

  In leaving academic research, says Kodosky, “we took a giant step back from what we were working on. ARL was cutting edge. Now it was customers who were doing the interesting experiments.” Still, he and Truchard say they have more impact on science by supplying tools than they would have had as researchers. “We can have a nonlinear effect on the productivity of the science and engineering community. There is plenty of anecdotal evidence that our virtual instrumentation can make people 5 to 10 times as productive,” Kodosky says. “I personally would find it frustrating [to do research] because it’s slow, but dropping by a customer’s site every couple of years is fun. We live vicariously through them.”

Toni Feder

Physics Today, July 2004

A expressão What’s more (2ª coluna, 1° Parágrafo) NÃO pode ser substituída por

 Utensílios de uso cotidiano e ferramentas que contêm ferro em sua liga metálica tendem a sofrer processo corrosivo e enferrujar. A corrosão é um processo eletroquímico e, no caso do ferro, ocorre a precipitação do óxido de ferro (III) hidratado, substância marrom pouco solúvel, conhecida como ferrugem. Esse processo corrosivo é, de maneira geral, representado pela equação química:

Uma forma de impedir o processo corrosivo nesses utensílios é 

A forma mais comum de observarmos um choque elétrico é quando alguém, indiscriminadamente, coloca os dedos na tomada ou toca algum componente elétrico ligado a ela. Tomadas e baterias são a nossa fonte mais comum de energia elétrica.



No entanto, dizer que elas fornecem diretamente energia é fisicamente incorreto. As tomadas fornecem às residências

As plantas são seres vivos que possuem grande importância para os seres humanos. Desde a antiguidade, elas têm sido utilizadas para diversas finalidades.

Você já utilizou algum produto que tenha sido feito a partir das plantas? Qual foi esse produto e para que ele foi utilizado?