Houses aren’t the only place where insulation can be seen in our world. Two kinds of animals — birds and mammals — maintain a constant body temperature despite the temperature of their surroundings. Both have evolved methods to control the flow of heat into and out of their bodies. Part of these strategies involve the use of insulating materials — fat, feathers, and fur — that serve to slow down the heat flow. Because most of the time an animal’s body is warmer than the environment, the most common situation is one in which the insulation works to keep heat in.            Whales, walruses, and seals are examples of animals that have thick layers of fat to insulate them from the cold arctic waters in which they swim. Fat is a poor conductor of heat and plays much the same role in their bodies as the fiberglass insulation in your attic.            Feathers are another kind of insulation. They are made of light, hollow tubes connected to each other by an array of small interlocking spikes. They have some insulating properties themselves, but their main effect comes from the fact that they trap air next to the body. This stationary air is a rather good insulator. For instance, in winter, a house sparrow has about 3,500 feathers, which maintain the bird’s normal temperature even in below-freezing weather. Birds often react to extreme cold by contracting muscles in their skin so that the feathers fluff out. This increases the thickness — and hence the insulating power — of the layer of trapped air. Incidentally, birds need insulation more than we do because their normal body temperature is 106°F.            Hair (or fur) is actually made up of dead cells similar to those in the outer layer of the skin. Like feathers, hair serves as an insulator in its own right and traps a layer of air near the body. In some animals (for example, polar bears) the insulating power of the hair is increased because each hair contains tiny bubbles of trapped air. The reflection of light from these bubbles makes polar bear fur appear white — the strands of hair are actually semitransparent.            Hair grows from follicles in the skin, and small muscles allow animals to make their hair stand up to increase its insulating power. Human beings, who evolved in a warm climate, have lost much of their body hair as well as the ability to make most of it stand up. There is a reminder of our mammalian nature, however, in the phenomenon of “goose bumps,” which is the attempt by muscles in the skin to make the nonexistent hair stand up.  You can infer from the passage that humans

Au travail  Complete these questions with a form of lequel. (Don’t forget the various forms it takes when a preposition is necessary!) (8 x 1 pt. each = 8 pts.) 1. Vous avez le choix entre deux assurances maladie. [lequel1] préférez-vous? 2. Ce sont tous des métiers intéressants. [lequel2] offrent les meilleurs emplois? 3. Nous employons ces deux conseillers. [lequel3] voulez-vous parler? 4. Ces deux candidats viennent de passer un entretien. [lequel4] voulez-vous me parler? 5. Ces deux professions sont exigeantes. Dans [lequel5] voulez-vous réussir? 6. Vous avez eu plusieurs mentions. [lequel6] parlez-vous? 7. Il y a plusieurs syndicats dans l’entreprise. [lequel7] avez-vous entendu parler? 8. Toutes ces candidates sont excellentes. [lequel8] avez-vous choisies pour l’entretien?

          Two automotive titans—Henry Ford and Alfred Sloan—symbolize the far-reaching changes that took place in American industry during the 1910s and 1920s. In 1913 and at the age of 50, Ford revolutionized American manufacturing by introducing the automated assembly line. By using conveyor belts to bring automobile parts to workers, he reduced his cars’ assembly time from 121?2 hours in 1912 to just 11?2 hours in 1914. Declining production costs allowed Ford to cut prices — six times between 1921 and 1925, reducing a new Ford’s cost to just $290. This was less than three months’ wages for an average American worker, and it made cars affordable for the average family. To lower employee turnover and raise productivity, Ford also introduced a minimum daily wage of five dollars in 1914—twice what most workers earned. In addition, he shortened the workday from nine hours to eight. Twelve years later, he reduced his workweek from six days to five. Ford proved the logic of mass production: expanded production allows manufacturers to reduce costs and increase the number of products sold. Ford also realized that higher wages allow workers to buy more products.           Alfred Sloan, the president of General Motors from 1923 to 1941, built his company into the world’s largest automaker. Sloan achieved this not by improving the production process but by adopting new approaches to advertising and marketing. He summed up his philosophy with these blunt words: “The primary object of the corporation was to make money, not just to make cars.” Sloan was convinced that Americans were willing to pay extra for luxury and prestige. His stance contrasted with Henry Ford’s. Ford, a farmer’s son, wanted to produce an inexpensive, practical vehicle with few extras. For instance, Ford said that his customers could have any color they wanted as long as it was black. Instead, Sloan advertised his cars as symbols of wealth and status. In 1927, he introduced the yearly model change, to convince motorists to trade in old models for new ones with flashier styling. Sloan also developed the idea of automotive “classes,” which classified cars by status, price, and level of luxury. According to this system, Chevrolets were less expensive than Buicks or Cadillacs. To make his cars affordable, he set up the nation’s first national consumer credit agency in 1919. If Henry Ford proved the power of mass production, Sloan revealed the importance of merchandising in a modern consumer society.  According to the passage, Ford’s minimum daily wage of five dollars

A balloon is filled to a volume of `x` L with `y` moles of gas at `p` °C. With pressure and temperature held constant, what will be the volume of the balloon if `z` moles of gas are released?   Enter a numeric response with 2 places after the decimal.

A 20.0 L container at 303 K holds a mixture of two gases with a total pressure of 5.0 atm. If there are `z` mol of Gas A in the mixture, what quantity in moles of Gas B is present?   Enter a numeric response with 2 places after the decimal.

A sample of gas at a constant volume initially has a temperature of `x` K with a pressure of `y` atm. The pressure changes to `z` atm. Calculate the final temperature.   Enter a numeric response with 2 places after the decimal.

A sample of gas at a constant pressure initially has a temperature of `x` K with a volume of `y` mL. The volume changes to `z` mL. Calculate the final temperature.   Enter a numeric response with 0 place after the decimal.

The ability to replace moles with volume in stoichiometric expressions when temperature and pressure are constant is justified by which gas law?

Write the balanced chemical equation based on the following description: aqueous calcium hydroxide reacts with aqueous nitric acid to produce the aqueous calcium nitrate and liquid water.

Using the following words write a sentence telling where you went last weekend. (10 pts.) Begin the sentence with the time expression. la/a/tienda/yo/ir/el fin de semana pasada .