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
2023-11-14
6
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 ascientific 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 them 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 thousand fold. [br] 【C9】
选项
A、believable
B、useable
C、practical
D、available
答案
D
解析
转载请注明原文地址:https://www.tihaiku.com/zcyy/3185006.html
相关试题推荐
TheLondon2012sustainabilitywatchdogembroiledinarowoverthesponsors
Todevelop_____,totrainthemselvestobehavelogicallyandtruthfully,andto
Tocompensateforthedeclineintheavailabilityoffossilfuelsinfutureyear
ThereareseveralpossibleexplanationsforthegreaterjobstabilityinJapan__
Whatistheprobabilityofthisevent______?A、tooccurB、occursC、occurringD、oc
Childrencanusuallydress_____bytheageoffive.A、themselvesB、themC、selvesD
Employeesshould______themselvesoftheopportunitytobuycheapsharesinthec
Highgradesaresupposedto______academicability,buthisactualperformance
Humanbeingshave______themselvestoverydiverseenvironmentswiththehelpof
Allofthetouristswouldhaveenjoyedthemselvesmoreifthere______offersfo
随机试题
Anewanalysisoffederalmoneythatpublicschoolsreceiveforlow-incomes
[originaltext]Whenmyfamilywentonsummervacation,weusuallymadeita
通常,项目整体变更管理过程涉及到负责批准或拒绝变更请求的变更控制委员会。下列关于
患者女,21岁。颈椎高位骨折脱位,并出现严重呼吸困难。当前,首先应采取的紧急处理
男孩5岁,自幼瘦弱,不爱活动,易疲劳,来院确诊无青紫,胸骨左缘Ⅲ~Ⅳ肋间可闻及Ⅲ
患者女,70岁,主诉轻微骨痛,劳动后加重,诊断为骨质疏松症,目前对患者生活影响最
抵押房屋订立抵押合同前已出租的,原房屋租赁合同( )。A.不受该抵押权影响
( )是指不同等级之间工资相差的幅度。A.工资差距 B.工资档次 C.薪酬
沈阳恒昌机电公司计划从德国进口一批液压电动机(属自动进口许可管理的机电产品),在
对于发电厂接地系统的设计,下列叙述错误的是?( )A.发电厂的接地网除应利用自
最新回复
(
0
)