发布时间：2016-04-08 来源：新东方在线 发布人：
Some people believe in the superstition that cats have nine lives, because cats can survive falls from high places with few, if any injuries. This gives the appearance that the cats return to life after sustaining a fatal accidents. The ability of the cat to survive these accidents that would kill humans or other animals is not due to [en]multiple
lives, but to several advantages they possess：[/en]
1. Their small size and low body weight soften the impact as they make contact with the ground after falling from great heights.
2. The highly developed inner ears of cats equip them with an unusually keen sense of balance. This sense of balance allows a cat falling upside down to right himself by rapidly determining his position, repositioning himself, and making any adjustments necessary to ensure that he lands on all fours. Since cats land on all four paws, the impact from landing on the ground is absorbed by all four.
3. Cats bend their legs when they land, which cushions the impact by spreading the impact, not only through bones that could easily break, but through the joints and muscles as well.
Most are surprised to learn that a cat stands a greater chance of survival if it falls from a higher place than from a lower place. New York veterinarians gathered data from their feline patients, which clearly supports this fact. Ten ercent of their patients died after falling from 2-6 stories, while only five percent of the fatalities occurred when their patients fell from 7-32 stories.
Laws of physics explain why these survival rates vary. All falling bodies, regardless or their masses, accelerate by 22 miles per hour of their falls. The falling object, after traveling a certain distance through the air reaches a final speed, or "terminal velocity," because the object’s friction with the air slows the fall. The smaller the object’s mass, and the greater its area, the more it will slow.
A cat falling from a higher floor, after it stops accelerating, spreads its legs into an umbrella shape, which increases the area against which the air must push and increases the friction, thus slowing the cat’s fall. Through the cats highly developed sense of balance, he buys more time to maneuver his body in preparation for landing on all fours. A cat falling from a lower eight does not have the opportunity to increase its body’s area, slow its fall, or position his body to land on all four feet.
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