Um pedaço de corda de 0,80 m de comprimento e peso 4,0 N é seguro sobre uma mesa sem atrito, ficando com a metade de seu comprimento pendurado para fora da mesa.

O trabalho mínimo necessário para puxar a parte pendurada da corda para cima da mesa é, em joules, de

Duas pequenas esferas metálicas e idênticas A e B estão eletrizadas com cargas !$ QA = 5 \, μC !$ e !$ QB = −1 \, μC !$. Colocam-se as esferas em contato e, a seguir, elas são separadas a uma distância de 10 cm. Considerando a constante eletrostática !$ k_0 = 9 . 10^9 N.m^2/C^2 !$, a intensidade da força elétrica de interação entre as esferas, em newton, vale

Antonio, Bruno e Celso disputaram uma corrida. Dadas as condições físicas e de preparo, Bruno tem o triplo de chances de vencer Antonio e Celso tem o quádruplo de chances de vencer Bruno. Dessa forma, a probabilidade de Bruno vencer é de

ONE DAY I WILL WRITE ABOUT THIS PLACE

A Memoir
By Binyavanga Wainaina
256 pp. Graywolf Press. $24.

Dear reader, I’ll save you precious time: skip this review and head directly to the bookstore for Binyavanga Wainaina’s stand-upand- cheer coming-of-age memoir, “One Day I Will Write About This Place.” [CONNECTIVE] written by an East African and set in East and Southern Africa, Wainaina’s book is not just for Afrophiles or lovers of post-colonial literature. This is a book for anyone who still finds the nourishment of a well-written tale preferable to the empty-calorie jolt of a celebrity confessional or Swedish mystery.

Not that Wainaina is likely to judge [PRONOUN] taste in books. In fact, at its heart, this is a story about how Wainaina was almost [TO EAT] alive by his addiction to reading anything available. “I am starting to read storybooks,” he says of his 11-year-old self, growing up in Nakuru, Kenya. “If words, in English, arranged on the page have the power to control my body in this world, this sound and language can close its folds, like a fan, and I will slide into its world, where things are arranged differently.”

As he leaves childhood [ADVERB 1] − “My nose sweats a lot these days, and my armpits smell, and I wake [ADVERB 2] a lot at night all wriggly and hot, like Congo rumba music” − Wainaina retreats further from the confusing realities of politics and adolescence and his big multinational family (his father a Kenyan businessman and farm owner, his mother a Ugandan salon owner) and deeper into a world of words. At school he is told, and believes, that he is supposed to become a doctor or a lawyer, an engineer or a scientist. But Wainaina seems constitutionally incapable of absorbing anything that would further a career in these fields.

By the time Wainaina leaves Kenya to attend university in South Africa, a country smoldering with the last poisonous fumes of apartheid, his addiction to books is complete. He drops out of school to pursue more completely a life of reading.

(Adapted from http://www.nytimes.com/2011/08/14/books/review/one-day-i-will-write-about-this-place-by-binyavanga-wainaina-book-review. html?pagewanted=all)

Segundo o texto,

Saving energy: i t starts at home

We already know the fastest, expensive way to slow climate change: use less energy. With a little effort, and not money, most of us could reduce our energy diets by 25 percent or more − the Earth a favor while also helping our pocketbooks. So what’s holding us back?

Scientists have reported recently that the world is heating up even faster predicted only a few years , and that the consequences could be severe if we don’t reducing emission of carbon dioxide and other greenhouse gases that are trapping heat in our atmosphere. But what can we about it as individuals? Will our efforts really any difference?

(Extracted from the National Geographic Magazine, March 2009)