(UNIT) A primeira lei da termodinâmica estabelece que a variação da energia interna de um sistema é dada por ∆U = Q - W, sendo Q o calor trocado pelo sistema e W o trabalho realizado. Se um gás ideal sofre uma compressão isocórica, então:

Para um mergulhador, cada 5 m de profundidade atingida corresponde a um acréscimo de 0,5 atm na pressão exercida sobre ele. Admita que esse mergulhador não consiga respirar quando sua caixa toráxica está submetida a uma pressão acima de 1,02 atm.

Para respirar ar atmosférico por um tubo, a profundidade máxima, em centímetros, que pode ser atingida pela caixa torácica desse mergulhador é igual a: 

(CFT-MG) A figura a seguir mostra uma célula vegetal.

A organela responsável pela secreção de glicoproteínas e alguns polissacarídeos, que integram a parede celular, está representada pelo número

(ESPCEX) We’re so well educated – but we’re useless

Record numbers of students have entered higher education in the past 10 years, but despite being the most educated generation in history, it seems that we’ve grown increasingly ignorant when it comes to basic life skills.

Looking back on my first weeks living in student halls, I consider myself lucky to still be alive. I have survived a couple of serious boiling egg incidents and numerous cases of food-poisoning, probably from dirty kitchen counters. Although some of my clothes have fallen victim to ironing experimentation, I think I have now finally acquired all the domestic skills I missed out in my modern education.

Educationist Sir Ken Robinson says that our current education system dislocates people from their natural talents and deprives us of what used to be passed from generation to generation – a working knowledge of basic life skills. Today’s graduates may have earned themselves distinctions in history, law or economics, but when it comes to simple things like putting up a shelf to hold all their academic books, or fixing a hole in their on-trend clothes, they have to call for help from a professional handyman or tailor.

Besides what we need to know for our own jobs, we must have practical skills. We don’t grow our own crops, build our own houses, or make our own clothes anymore; we simply buy these things. Unable to create anything ourselves, what we have mastered instead is consumption.

Sociologist Saskia Sassen argues that the modern liberal state has created a middle class that isn’t able to “make” anymore. I suggest that we start with the immediate reintroduction of some of the most vital aspects of “domestic science” education. Instead of only maths, language and history, we should create an interactive learning environment in schools where craftsmanship and problem-solving are valued as highly as the ability to absorb and regurgitate information. We need to develop children into people that not only think for themselves, but are also able to act for themselves.

Adapted from http://www.guardian.co.uk/education/mortarboard/2013/feb/25/well-educated-but-useless

In the sentence “I think I have now finally acquired all the domestic skills I missed out in my modern education.” (paragraph 2), the words missed out mean:

O Prêmio Nobel de Química de 2000 deveu-se à descoberta e ao desenvolvimento de polímeros condutores. Esses materiais têm ampla aplicação em novos dispositivos eletroluminescentes (LEDs), células fotovoltaicas etc. Uma propriedade-chave de um polímero condutor é a presença de ligações duplas conjugadas ao longo da cadeia principal do polímero.

ROCHA FILHO, R C. Polímeros condutores: descoberta e aplicações. Química Nova na Escola. n. 12, 2000 (adaptado).

Um exemplo desse polímero é representado pela estrutura