Too high: No O, down you go
Q. The meteorite-slamming-into-Earth theory to explain the demise of the dinosaurs 65 million years ago is well known. What's the too-high-flying balloonist theory? P. Fogg
A. In the Andes Mountains of Chile and Peru, at 17,400 feet (5300 m.), miners must make do breathing air at only 50 percent the oxygen at sea level, say Brian J. Skinner, et al. in The Blue Planet: An Introduction to Earth System Science.
Still, miners who grow up in the region become acclimated. For brief periods, some can go on even less than the 50 percent. Mountain climbers in the Himalayas have camped for weeks at 23,000 feet (7000 m.), where the oxygen level is only 44 percent of the sea-level value.
"This is probably very close to the lower human limit because balloonists who have attempted longtime flights above 7000 meters have found it necessary to breathe bottled oxygen; some who attempted to fly without extra oxygen perished in the attempt."
Richer air can be a problem as well. Beginning at 40 percent richer concentration than sea level, oxygen becomes toxic, and breathers start to "burn up." So survivability demands oxygen levels from 44 percent below to 40 percent above sea-level air.
Now to the dinos: Air trapped in ancient amber suggests oxygen content 100 million years ago in the early Cretaceous period was 40 percent higher than today, say the researchers. Although the dinos were probably finished off by a meteorite impact, they had been declining before that. As the Cretaceous came to a close, oxygen levels started to decline. But perhaps because the dinos had developed small lungs in the oxygen-rich earlier atmosphere, now they couldn't cope.
"And so, like high-flying balloonists, they died out from respiratory stress."
Q. Giving 110 percent in sporting competition sounds good, but when might giving only 95 percent serve athletes better? L. Aller
A. On a test of 400-meter track runners, the ones asked to hold back to 95 percent of capacity actually had better times, say Robert S. Weinberg and Daniel Gould in Foundations of Sport & Exercise Physiology, 3rd Edition. The 110-percenters were using all their energies and muscular capacities, but running is done most effectively when some muscles are contracting while others are relaxing.
Muscles group as agonists and antagonists, performing opposite actions; firing off both simultaneously sacrificed speed. The 95 percenters, using agonists while relaxing antagonists at appropriate times, won the race.
In baseball, an overthrowing pitcher using all his muscles not only loses control, but the pitch won't even go as fast, say Weinberg and Gould. For maximum effectiveness, "some of the muscles of the arm– particularly the flexor muscles like the biceps– need to relax as the extensors, such as the triceps, do most of the work."
Q. Imagine flipping a "fair" coin again and again. At 100 flips, you'll probably be pretty close to 50 heads, 50 tails. At 1000, you'll probably be pretty close to 500H-500T, as things tend to "even out over the long run." So answer this: Which is likely to be closer in actual count of heads vs. tails– the 100 flips or the 1000 flips? D. Trump
A. Most people will guess the 1000 flips, assuming that "evening out" means the number of heads and the number of tails tend to get closer and closer with larger numbers of flips, says math professor Mike Dawes, of the University of Western Ontario. But intuition can play tricks here. What does tend to even out are the percentages of heads and tails, moving closer and closer to 50 percent-50 percent as the flip count rises, but not close to 500-500 or 5000-5000, etc.
Most likely you will see the actual difference in the number of heads and tails grow and grow. For instance, the chance of getting a split somewhere between 45 and 55 with 100 tosses is almost 73 percent, says Dawes. But for the H-T count to be this close (within a range of +5 to -5) after 1000 flips is much less likely, about 27 percent; and even less likely, about 9 percent, after 10,000 flips.
Q. Kite-flying Ben Franklin is often depicted doing his famous "lightning is electricity" experiment during a raging thunderstorm. What's wrong with this picture? T. Jefferson
A. Franklin was never that stupid, says Jearl Walker in The Flying Circus of Physics. A lightning strike to the kite would have destroyed it, the twine, the trivial silk shield and possibly Franklin himself. Rather, he wisely flew his kite before the full storm arrived.
In Europe, G. W. Richmann, in attempting to duplicate Franklin's experiment, became an apparent victim of a mysterious type of lightning called "ball lightning": "A pale blue fireball about the size of a fist left the lightning rod in his lab, floated quietly to Richmann's face, and exploded. With a red spot on his forehead and two holes in one of his shoes, Richmann was left dead on thefloor."
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