How did “wink” become a unit of sleep, as in “didn’t sleep a wink” or “40 winks”? Also, says David Roubik, an entomologist at the Smithsonian Tropical Research Institute in Panama, the parting of bee and stinger exposes a gland that releases a pheromone alerting other colony members to sting the victim at that spot. This defense works for the colony, if not for the individual: Those females, worker bees, cannot reproduce, but their self-sacrifice defends the egg-laying queen. Why would natural selection favor such a defense mechanism? It’s generally known that a female honeybee’s stinger will rip away after stinging, fatally for the bee. They removed it in winter, to keep it from being broken up by river ice, and replaced it in spring throughout the war. Soldiers stretched the iron barrier, supported by log rafts, across the river at West Point. The chain consisted of 750 links, each two feet long and weighing more than 100 pounds. In 1778, the colonists, who then produced 14 percent of the world’s iron, forged the Great Chain to prevent a Royal Navy invasion upriver, says David Miller III, associate curator at the National Museum of American History. Because the downward and forward forces are nearly equal, the astronauts are not pulled in any specific direction, so they float.ĭid the colonists really mount a massive chain across the Hudson River during the American Revolution? The required engineering skill and smithing manpower would seem beyond them. They’re falling toward Earth and moving forward at about the same velocity. #ANCIENT SPACE STATION ORBITING EARTH FREE#They experience weightlessness not because of a lack of gravity but because the ISS, and they, are orbiting Earth in constant free fall, says Valerie Neal, curator of space history at the National Air and Space Museum. Why do astronauts aboard the International Space Station seem to float? The ISS is only about 200 miles above Earth-where, according to Newton, gravity is almost as strong as it is here on the ground.
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