Problem: Incandescent light bulb:

While inert gas reduces filament evaporation, it also conducts heat from the filament, thereby cooling the filament and reducing efficiency. At constant pressure and temperature, the thermal conductivity of a gas depends upon the molecular weight of the gas and the cross sectional area of the gas molecules. Higher molecular weight gasses have lower thermal conductivity, because both the molecular weight is higher and also the cross sectional area is higher. Xenon gas improves efficiency because of its high molecular weight, but is also more expensive, so its use is limited to smaller lamps.

What is the advantage of using inert gas in a light bulb?
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A: reduces filament evaporation


Problem: Guam:

Despite Magellan's visit, Guam was not officially claimed by Spain until January 26, 1565 by General Miguel López de Legazpi.:46 From 1565 to 1815, Guam and the Northern Mariana Islands, the only Spanish outpost in the Pacific Ocean east of the Philippines, was an important resting stop for the Manila galleons, a fleet that covered the Pacific trade route between Acapulco and Manila.:51 To protect these Pacific fleets, Spain built several defensive structures which are still standing today, such as Fort Nuestra Señora de la Soledad in Umatac. It is the biggest single segment of Micronesia, the largest islands between the island of Kyushu (Japan), New Guinea, the Philippines, and the Hawaiian Islands.

What did Spain build to protect their fleet at Guam?
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A: built several defensive structures


Problem: Richard Feynman:

Feynman devoted the latter half of his book What Do You Care What Other People Think? to his experience on the Rogers Commission, straying from his usual convention of brief, light-hearted anecdotes to deliver an extended and sober narrative. Feynman's account reveals a disconnect between NASA's engineers and executives that was far more striking than he expected. His interviews of NASA's high-ranking managers revealed startling misunderstandings of elementary concepts. For instance, NASA managers claimed that there was a 1 in 100,000 chance of a catastrophic failure aboard the shuttle, but Feynman discovered that NASA's own engineers estimated the chance of a catastrophe at closer to 1 in 200. He concluded that the space shuttle reliability estimate by NASA management was fantastically unrealistic, and he was particularly angered that NASA used these figures to recruit Christa McAuliffe into the Teacher-in-Space program. He warned in his appendix to the commission's report (which was included only after he threatened not to sign the report), "For a successful technology, reality must take precedence over public relations, for nature cannot be fooled."

Who did NASA recruit by using flawed safety numbers?
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A: Christa McAuliffe


Problem: BeiDou Navigation Satellite System:

In 2007, the official Xinhua News Agency reported that the resolution of the BeiDou system was as high as 0.5 metres. With the existing user terminals it appears that the calibrated accuracy is 20m (100m, uncalibrated).

In 2007, what was the reported resolution of the BeiDou system?
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A:
as high as 0.5 metres