Science Quiz

2. One of the biggest newsmakers of 1997 was named Dolly. Who is Dolly, and what is her claim to fame?

• Dolly (full name, Kenmoor Silver Doll) was the horse that won racing's Triple Crown.
  Sorry. There was no horse in 1997 that won racing's Triple Crown (the Kentucky Derby, the Preakness, and the Belmont). Dolly is a sheep, not a horse.
• Dolly is the new singing sensation of Chinese hip-hop music. On September 11, she drew the largest concert crowd ever to a stadium outside Beijing.
  No way. As far as we know, there are no Chinese hip-hop stars.

  Dolly is a sheep. To be a clone means Dolly's cells contain exactly the same genetic information as those of her "parent." She is the first adult mammal to be successfully cloned. Many people wonder whether it will ever be possible to clone humans and if so, whether it would be morally right.

  Suppose there were dozens of clones of a famous athlete, singer, or math genius? What do you think?

• Dolly is a cloned sheep.
  That's right! Dolly is a sheep that was cloned in a laboratory in Scotland.

  To be a clone means Dolly's cells contain exactly the same genetic information as those of her "parent." She is the first adult mammal to be successfully cloned. Many people wonder whether it will ever be possible to clone humans and if so, whether it would be morally right.

  Suppose there were dozens of clones of a famous athlete, singer, or math genius? What do you think?

3. The Joneses have built a rectangular house with southern exposures on all four sides. Where is the house?

• It's in outer space.
  Not really. It's true that there are no directions in space, so you could build a house out there and call all the directions south, but that wouldn't really make them south.

  Directions are defined by the rotation of a planet in relation to its axis. On planet Earth, there is only one place that faces south on all four sides, and that's at the North Pole.

• It's at the North Pole.
  You got it! The only place on Earth that faces south in all directions is the North Pole. Their next-door neighbors must be Santa and Mrs. Claus.

  When the Joneses built their house, they had to be very careful to choose the geographical North Pole and not the magnetic North Pole. Compass needles point to the magnetic North Pole, which is on Bathurst Island in northern Canada.

  The magnetic pole is about 1,000 miles from the geographical pole, which is on a drifting ice pack in the Arctic Ocean. This means the Joneses will have a hard time keeping their perfect southern exposure at all times. And of course their house will be in darkness for about half the year.

  It seems a high price to pay for a southern exposure.

• It's at the South Pole.
  No way. In spite of the fact that the South Pole is as far south as you can get, a house there would not be facing south. It would actually be facing north. The North Pole is the only place where you face south on all sides.

4. Smoke jumpers parachute into dangerous places to fight fires. They fall faster than ordinary parachutists. Why?

• Because smoke jumpers carry heavy equipment.
  Nope. Once a falling object reaches what's called "terminal velocity," it can't fall any faster, no matter what it weighs. The truth is, hot air is thinner than cold air, so there's less of it to push against a falling body and slow it down.
• The hot air near a large fire is thinner and offers less resistance.
  Yes indeed! Hot air is thinner than cold air, so there's less of it to push against a falling body and slow it down.

  Smoke jumpers know that their parachutes have to open sooner than those of other jumpers, or they risk hitting the ground too hard and hurting themselves. The hot air is thinner than cold air for the same reason any substance is less dense when hot -- the heat energy drives the molecules farther apart. And the less dense a substance is, the easier it is to move through it. That's why, for example, it is less work to wade through water than through mud.

• They use smaller parachutes so they can get to the ground in a hurry.
  Sorry. Arriving by parachute is pretty fast anyway. That's why the smoke jumpers come in by plane instead of hiking to where the fire is. It would be more dangerous for them to fall faster because they would hit the ground harder, and they already hit the ground hard enough as it is. It's the less dense air that makes them fall faster.

5. On a hot, sunny day around sunset, there is a thunderstorm that cools things off. That evening, you notice fog that rises off the road. Why?

• Water evaporates from the road because it is warmer than the air. Then the water vapor condenses in the cooler air above it.
  You got it! The road surface absorbs heat from the sun. Then the heat serves to vaporize some of the rain water, which forms visible fog in little clouds above the surface, where the air is cooler. The same thing is probably happening in the nearby fields and forests, only it is more visible on a road.

  Fog, (like mist, steam, and clouds) is made of tiny drops of water vapor suspended in the air. Other common fog types are associated with warm air over cold ocean currents, moist air moving upslope and thus into colder temperatures, and cold air being blown over warmer ocean waters.

  It's not always easy to tell the difference between fog, mist, and clouds. Europeans say it's a fog if you can't see any farther than five-eighths of a mile. If you can see farther than that, they call it mist, but in North America, we often use the term mist for a very fine rain. Whatever you call it, it's damp.

• The fog forms from small pieces of the thunder cloud that sink to earth.
  Not so. Clouds sometimes sink to ground level, but not under these conditions. This type of fog rises from the warm road surface and condenses in the cooler air.
• Water condenses on the road surface because it is cold.
  'Fraid not. The road is warm, not cold. That is why the water evaporates from it and then condenses in the cooler air.