(CEFET) A figura seguinte representa um fenômeno ocorrido ao atritar um pente em uma fl anela e depois aproximá-lo de papel picado pelo fato de o pente ficar eletrizado por atrito.

Tendo em vista a evolução dos modelos atômicos, de Dalton até Bohr, o primeiro modelo que explica o fenômeno da eletrização é o de

(ENEM 2015 2º APLICAÇÃO)

Ao se perfurar um poço no chão, na forma de um cilindro circular reto, toda a terra retirada é amontoada na forma de um cone circular reto, cujo raio da base é o triplo do raio do poço e a altura é 2,4 metros. Sabe-se que o volume desse cone de terra é 20% maior do que o volume do poço cilíndrico, pois a terra fica mais fofa após ser escavada.

Qual é a profundidade, em metros, desse poço?

(MACKENZIE) Com o intuito de facilitar seu trabalho, um operário construiu um artifício com cordas e polias fixas ideais e ainda uma barra homogênea de comprimento L= 20 m, articulada no ponto A. A massa da barra vale M_B= 60 kg  e o peso do bloco levantado tem módulo Q= 500 N.

Considerando-se que o sistema está em equilíbrio no instante em que é retratado, que o módulo da aceleração gravitacional local seja g= 10 m/s², que o trecho BC da corda esteja perpendicular à barra e que o valor do ângulo é θ = 53°, afirma-se corretamente que o módulo da reação horizontal da força na barra no ponto A vale, em N (newton),

(Dados: cos 37° = 0,8 e sen 37° = 0,6)

(UERJ) What’s in a name?

The trouble with lingo

Remember the campaign in New York for garbage collectors to be called sanitation engineers?

Near the top of the strike’s agenda was the matter of getting the respect due to the people doing such essential work. Unfortunately, the new euphemistic title clarified nothing about the work and by now is either simply not heard for what it means, or is used in moments of gentle disdain. ¹⁰A clearer term may have both generated the respect desired and withstood the test of time.

Clarity and sincerity matter. Terms which mislead, confuse or cause offence can become a distraction from the real content of public debate. In the search for consensus, ²since public understanding is harder to change than terminology, changing the terminology might be a better place to start. No additional prejudice or emotion should be brought to a debate by the terminology used in it. Here are two examples.

Genetic Engineering and Genetic Modification

Despite the insistence of biotech scientists that genes of completely different species are no longer being mixed, the message isn’t being heard. They insist that they are now involved only in developments which simply hasten the natural processes of selective and cross breeding or cross pollination. As farmers and horticulturists have been doing exactly this, unquestioned, for years, they cannot understand public resistance.

The problem may well be the terminology. In this context, the words “scientific” or “genetic” have been irreparably sullied. If “genetic engineering” has, in the public’s view, become synonymous with the indiscriminate mixing of genes, and if the softer label “genetically modified” hasn’t been able to shake off a perception of sinister overtones, these terms might as well be dropped – or left attached only to experiments in Dr. Frankenstein’s laboratory.

Ideally, a new agricultural term would leave out the word “genetic” altogether: it seems to frighten the public. Assuming it described science’s benign genetic activities accurately, ⁸the term “productivity breeding” is not a trivial call for a euphemism; besides, it would probably encounter less public opposition.

So, let’s have new terms for selective cross breeding by scientists who simply speed up the same process that is carried out in nature.

 Clean coal*

³If this new term was intended to be clear, it hasn’t worked.

In “Politics and the English Language” (1946), George Orwell wrote that ⁴because so much political speech involves defending the indefensible, ¹¹it has to consist largely of euphemism. ⁶He insisted that, in politics, ⁷these euphemisms are “swindles” and “perversions” left deliberately vague in order to mislead. Deliberate or not, ¹²“clean coal” is one of these. Aside from being a contradiction in terms, the name is misleading, creating the impression of the existence of a new type of coal. In fact, it is ¹³ordinary coal which has been treated to “eliminate” most of its destructive by-products, which are then buried. The whole process produces emissions. ⁵This, though, isn’t clear when it is simply labelled “clean coal”. The term just doesn’t seem sincere. ⁹It’s a red rag to any green. It’s not asking too much to expect the term describing these procedures to be more accurate. A clearer term would be less provocative.

¹So, what’s in a name? A lot. There’s the possibility of confusion, prejudice, perversions and swindles. For the sake of fair debate, let’s mean what we say and say what we mean.

 * Coal: carvão

SEEARGH MACAULAY www.londongrip.com 

The logical relationship between clauses establishes different notions. An example which expresses the notion of concession is indicated in: