(EEAR) Um móvel completa 1/3 de um percurso com o módulo da sua velocidade média igual a 2km/h e o restante com o módulo da velocidade média igual a 8 km/h. Sendo toda a trajetória retilínea, podemos afirmar que a velocidade média desse móvel durante todo o percurso, em km/h foi igual a

Três esferas metálicas, M₁, M₂ e M₃, de mesmo diâmetro e montadas em suportes isolantes, estão bem afastadas entre si e longe de outros objetos.Inicialmente M₁ e M₃ têm cargas iguais, com valor Q, e M₂ está descarregada. São realizadas duas operações, na sequência indicada:

I.A esfera M₁ é aproximada de M₂ até que ambas fiquem em contato elétrico. A seguir, M₁ é afastada até retornar à sua posição inicial.

II.A esfera M₃ é aproximada de M₂ até que ambas fiquem em contato elétrico. A seguir, M₃ é afastada até retornar à sua posição inicial.

 Após essas duas operações, as cargas nas esferas serão cerca de:

(ESPM) Emerging economies 

The Great Deceleration

The emerging-market slowdown is not the beginning of a bust. But it is a turning-point for the world economy

WHEN a champion sprinter falls short of his best speeds, it takes a while to determine whether he is temporarily on poor form or has permanently lost his edge. The same is true with emerging markets, the world economy’s 21st-century sprinters. After a decade of surging growth, in which they led a global boom and then helped pull the world economy forwards in the face of the financial crisis, the emerging giants have slowed sharply.

China will be lucky if it manages to hit its official target of 7.5% growth in 2013, a far cry from the double-digit rates that the country had come to expect in the 2000s. Growth in India (around 5%), Brazil and Russia (around 2.5%) is barely half what it was at the height of the boom. Collectively, emerging markets may (just) match last year’s pace of 5%. That sounds fast compared with the sluggish rich world, but it is the slowest emerging-economy expansion in a decade, barring 2009 when the rich world slumped.

This marks the end of the dramatic first phase of the emerging-market era, which saw such economies jump from 38% of world output to 50% (measured at purchasing-power parity, or PPP) over the past decade. Over the next ten years emerging economies will still rise, but more gradually. The immediate effect of this deceleration should be manageable. But the longer-term impact on the world economy will be profound.

 Running out of puff

 In the past, periods of emerging-market boom have tended to be followed by busts (which helps explain why so few poor countries have become rich ones). A determined pessimist can find reasons to fret today, pointing in particular to the risks of an even more drastic deceleration in China or of a sudden global monetary tightening. But this time a broad emerging-market bust looks unlikely.

China is in the midst of a precarious shift from investment-led growth to a more balanced, consumption-based model. Its investment surge has prompted plenty of bad debt. But the central government has the fiscal strength both to absorb losses and to stimulate the economy if necessary. That is a luxury few emerging economies have ever had. It makes disaster much less likely. And with rich-world economies still feeble, there is little chance that monetary conditions will suddenly tighten. Even if they did, most emerging economies have better defences than ever before, with flexible exchange rates, large stashes of foreign-exchange reserves and relatively less debt (much of it in domestic currency).

That’s the good news. The bad news is that the days of record-breaking speed are over. China’s turbocharged investment and export model has run out of puff. Because its population is ageing fast, the country will have fewer workers, and because it is more prosperous, it has less room for catch-up growth. Ten years ago China’s per person GDP measured at PPP was 8% of America’s; now it is 18%. China will keep on catching up, but at a slower clip.

That will hold back other emerging giants. Russia’s burst of speed was propelled by a surge in energy prices driven by Chinese growth. Brazil sprinted ahead with the help of a boom in commodities and domestic credit; its current combination of stubborn inflation and slow growth shows that its underlying economic speed limit is a lot lower than most people thought. The same is true of India, where near-double-digit annual rises in GDP led politicians, and many investors, to confuse the potential for rapid catch-up (a young, poor population) with its inevitability. India’s growth rate could be pushed up again, but not without radical reforms—and almost certainly not to the peak pace of the 2000s.

Jul 27th 2013/www.economist.com

The pronoun they in the underlined sentence of the fifth paragraph of the text: “Even if they did, …” refers to  

Os dois milhões de habitantes da Faixa de Gaza e as centenas de milhares de israelenses que moram em torno do território viveram o dia mais violento depois da devastadora guerra de 2014. O Hamas e a Jihad Islâmica dispararam mais de 450 projéteis, entre foguetes e granadas de morteiro, contra Israel, matando três pessoas. As represálias da aviação militar israelense contra 260 objetivos das milícias em Gaza mataram 21 pessoas.

Disponível em: https://brasil.elpais.com. Acesso em: 1 set. 2020 (adaptado).

Atualmente, o território no qual ocorreu o violento confronto é um (a)

(FUVEST 2017 1° FASE) Células a combustível são opções viáveis para gerar energia elétrica para motores e outros dispositivos. O esquema representa uma dessas células e as transformações que nela ocorrem.

A corrente elétrica (i), em ampère (coulomb por segundo), gerada por uma célula a combustível que opera por 10 minutos e libera 4,80 kJ de energia durante esse período de tempo, é

Note e adote:

•  Carga de um mol de elétrons = 96.500 coulomb.