A imagem mostra o astronauta Kevin Ford observando uma bolha de água na qual sua imagem é refratada. Nesse caso, a bolha de água funciona como uma lente.

Considerando a posição da bolha em relação ao astronauta e à câmera, a distância focal da bolha-lente e o comportamento dos raios luminosos refratados pela bolha, determina-se que a foto obtida resultou do fato de a bolha estar mais próxima

(FUVEST 2013 1° FASE) Um caminhão sobe uma ladeira com inclinação de 15º. A diferença entre a altura final e a altura inicial de um ponto determinado do caminhão, depois de percorridos 100 m da ladeira, será de, aproximadamente,

Dados:

• $\sqrt{\smash[b]{3}}$\sqrt{\smash[b]{3}}  ≅ 1,73
• 
  

Most people today have a mobile phone. In fact, many people can't imagine how they ever got along without a portable phone. However, many people also complain about cell phone users. People complain about other people loudly discussing personal matters in public places. They complain when cell phones ring in movie theaters and concert halls. They complain about people driving too slow, and not paying attention to where they are going because they are talking on a cell phone. And they complain about people walking around talking to people who aren't there.

Whenever a new communications technology becomes popular, it changes the way society is organized. Society has to invent rules for the polite way to use the new devices. Our social etiquette, our rules of politeness for cell phones, is still evolving.

Disponível em: www.indianchild.com. Acesso em: 28 fev. 2012 (adaptado).

O uso de celulares em lugares públicos tem sido prática corrente. O texto aponta que essa prática tem gerado

(UNESP) Is there anything I can do to train my body to need less sleep?

Karen Weintraub

June 17, 2016

Many people think they can teach themselves to need less sleep, but they’re wrong, said Dr. Sigrid Veasey, a professor at the Center for Sleep and Circadian Neurobiology at the University of Pennsylvania’s Perelman School of Medicine. We might feel that we’re getting by fine on less sleep, but we’re deluding ourselves, Dr. Veasey said, largely because lack of sleep skews our self-awareness. “The more you deprive yourself of sleep over long periods of time, the less accurate you are of judging your own sleep perception,” she said.

Multiple studies have shown that people don’t functionally adapt to less sleep than their bodies need. There is a range of normal sleep times, with most healthy adults naturally needing seven to nine hours of sleep per night, according to the National Sleep Foundation. Those over 65 need about seven to eight hours, on average, while teenagers need eight to 10 hours, and school-age children nine to 11 hours. People’s performance continues to be poor while they are sleep deprived, Dr. Veasey said.

Health issues like pain, sleep apnea or autoimmune disease can increase people’s need for sleep, said Andrea Meredith, a neuroscientist at the University of Maryland School of Medicine. A misalignment of the clock that governs our sleep-wake cycle can also drive up the need for sleep, Dr. Meredith said. The brain’s clock can get misaligned by being stimulated at the wrong time of day, she said, such as from caffeine in the afternoon or evening, digital screen use too close to bedtime, or even exercise at a time of day when the body wants to be winding down.

 (http://well.blogs.nytimes.com. Adaptado.)

No trecho do segundo parágrafo “Those over 65 need about seven to eight hours, on average, while teenagers need eight to 10 hours”, o termo em destaque tem sentido de

(UNICENTRO) O coeficiente de solubilidade corresponde à quantidade máxima dissolvida de uma substância, a uma dada temperatura, em uma quantidade padrão de solvente.

Admitindo-se que o coeficiente de solubilidade do nitrato de potássio, KNO₃ (s) a 10º C, é de 20,0 g/100,0 g de água, é correto afirmar que a mistura de 10,0 g de KNO₃ (s) com 250,0 g de água, a essa temperatura, formará: