首页
登录
职称英语
The ability of falling cats to right themselves in midair and land on their
The ability of falling cats to right themselves in midair and land on their
游客
2023-11-20
27
管理
问题
The ability of falling cats to right themselves in midair and land on their feet has been a source of wonder for ages. Biologists long regarded it as an example of 【C1】______ by natural selection, but for physicists it bordered on the miraculous. Newton’s laws of motion 【C2】______ that the total amount of spin of a body cannot change 【C3】______ an external torque speeds it up or slows it down. If a cat has no spin when it is released and experiences no external torque, it ought not to be able to 【C4】______ as it falls.
In the speed of its execution, the 【C5】______ of a tumbling cat resembles a magician’s trick. The gyrations of the cat in midair are 【C6】______ fast for the human eye to follow, so the process is obscured.【C7】______ the eye must be speeded up, or the cat’s fall slowed down for the phenomenon to be observed. A century ago the former was accomplished 【C8】______ high-speed photography using equipment now 【C9】______ in any pharmacy. But in the nineteenth century the 【C10】______ on film of a falling cat constituted a scientific experiment.
The experiment was described in a paper presented to the Paris Academy in 1894. Two sequences of twenty photographs【C11】______ one from the side and one from behind, 【C12】______ a white cat in the act of righting itself. Grainy and quaint 【C13】______ they are, the photos show that the cat was dropped upside down, with no initial spin, and still landed on its feet. Careful analysis of the photos reveals the secret. As the Cat rotates the front of its body 【C14】______ , the rear and tail twist counterclockwise, 【C15】______ the total spin remains zero, 【C16】______ Newton’s laws. Halfway down, the cat pulls in its legs before reversing its twist and then extends them again, 【C17】______ the desired end result. The explanation was that while no body can acquire spin without torque, a flexible one can readily change its 【C18】______ . Cats know this instinctively, but scientists could not be sure how it happened 【C19】______ they increased the speed of their 【C20】______ a thousandfold. [br] 【C14】
选项
A、counterclockwise
B、upside down
C、clockwise
D、anticlockwise
答案
C
解析
转载请注明原文地址:https://tihaiku.com/zcyy/3204571.html
相关试题推荐
Husbandandwifewithacommondutytothecountrywillfindthemselves______cl
Noonecandenythatpesticidehaveimprovedtheabilityoffarmerstobrin
Noonecandenythatpesticidehaveimprovedtheabilityoffarmerstobrin
Noonecandenythatpesticidehaveimprovedtheabilityoffarmerstobrin
Noonecandenythatpesticidehaveimprovedtheabilityoffarmerstobrin
Noonecandenythatpesticidehaveimprovedtheabilityoffarmerstobrin
Noonecandenythatpesticidehaveimprovedtheabilityoffarmerstobrin
Noonecandenythatpesticidehaveimprovedtheabilityoffarmerstobrin
Noonecandenythatpesticidehaveimprovedtheabilityoffarmerstobrin
Noonecandenythatpesticidehaveimprovedtheabilityoffarmerstobrin
随机试题
【B1】[br]【B3】[originaltext]WhowillrunintotheNewYearfirst?Couldyou
[originaltext]W:Yourjacketissobeautiful.Didyourwifemakeitforyou?M
BeingwithSeamusHeaneywaslikebeingwithtwopeopleatonce.Ontheone
本次活动的目标是什么?
乙酰CoA羧化酶催化的反应其产物是( )。A.丙二酰CoA B.丙酰CoA
根据《测绘生产质量管理规定》,测绘单位的下述质量目标中,错误的是( )。A.产
逆向思维是一种比较特殊的思维方式,它的思维取向是与常人的思维取向相反。逆向思维并
各种运输方式内外部的各个方面的构成和联系,就是( )。 A.运输系统
长倒卵形,表面灰褐色,带紫黑色斑点,有数条纵棱,气微,味苦后微辛而稍麻舌的是A.
在短途往复式运输线路上,甩挂运输通常采用的运输形式是()。A:驮背运输 B:载
最新回复
(
0
)