The Readers Ask
Why don't school buses have seat belts? Why are barns red? Will 2000 affect my computer? What happened to the SR-71 spy plane? Lightning: up or down?
Q My daughter wants to know "if seatbelts are so important and save lives, why don't we have them on most school buses?" - Prof. Daniel R. Kempton, Sycamore, Ill.Skip to next paragraph
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A Instead of seat belts, bus designers use a concept called "compartmentalization." Protection comes from seats that are high-backed, well-cushioned, and placed close together. In 1989, the National Academy of Sciences studied the safety issue at the request of Congress, and concluded that compartmentalization was still more effective than belts. There are several arguments against belts. Belts could become weapons if children become rowdy. In case of accident, only one adult (the driver) is available to make sure all children get out of their belts. And finally, the standard three-point belt system in cars has not been perfected for buses, and old-fashioned lap belts could cause more injuries than they prevent.
Q Why are barns usually painted red? - Jan Mooney, Baltimore, Maryland
A A mix of milk and red ochre, a clay colored by iron oxide, was used on early American farms to coat barns. Milk was plentiful, and when mixed with ochre and dried, it forms a plastic-like coat that prevents weathering. Milk paint came into use in the 1700s and continued until the 1930s. It declined in popularity as farmers phased out dairy herds. Shakers also painted their barns red, but used ox blood in place of ochre. Red barns were mostly found in the North. Southerners either didn't paint barns, or used lampblack that resulted in a grayish color. The trend now is to paint barns white. It keeps them cooler.
Q Why do racing cars have smooth tires? - Josh Caldwell, Dolores, Colo.
A Racing tires are called "slicks." They are smooth because treads are not needed on dry roads. "Slicks" grip dry surfaces better than tires with treads because they put more rubber on the road. A spokesman at Goodyear says that ordinary auto tires have treads that allow cars to drive safely on wet streets. In rain, tires may move more than a gallon of water per second to maintain grip. Zigzag treads allow tires to sponge up and pump out water. Racers use treaded tires when it rains.
Q Is the US military still flying the SR-71 spy plane? Surveillance flights over Iraq are being done with the U-2, which Iraq threatens to shoot down. I think I heard once that the SR-71 could fly faster than a surface-to-air missile. So why not use the SR-71? - Mark Johnson, Hillsboro, Ore.
A US Air Force SR-71 "Blackbirds" - the world's fastest and highest-flying planes - were mothballed in 1990. Two of them were returned to service in 1997. An Air Force spokesman calls the decision to reactivate the planes "political," since satellites now can do the job. The SR-71 broke many speed records (it flies about 2,200 miles per hour) and altitude records (over 85,000 feet). It once went from L.A. to Washington, D.C., in 64 minutes.
Q In the Titanic [the ship, not the movie], were there really only six people who weren't in one of the 20 lifeboats who survived? - June Louks, Palisades, Calif.
A Actually, the number was seven. Fourteen people were pulled out of the water alive after the ship went down, but only half survived, according to Titanic scholar Susan Wels. Around midnight, Capt. E.J. Smith ordered his crew to make 16 lifeboats and four collapsible boats ready to evacuate passengers; but many of the boats were not filled to capacity. Lifeboat Seven could hold 65, but only 28 boarded. Lifeboat One could hold 40, but only 12 boarded. Of 2,228 passengers, only 705 survived.