首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
The ability of falling cats to right themselves in midair and land on their feet has been a source of wonder for ages. Biologist
The ability of falling cats to right themselves in midair and land on their feet has been a source of wonder for ages. Biologist
admin
2010-02-17
35
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.
【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://kaotiyun.com/show/iOnK777K
0
专业英语四级
相关试题推荐
Theroleofteachersineducationextendspastresponsibilityofpassingalonginformation.Asthenamesuggests,theprimaryf
Whetheryou’retheCEOofaFortune500company,orateenageentrepreneurjuststartingout,communicationskillsarevitally
Thereareseveralpossiblerelationshipsbetweenlanguageandsociety.Oneisthatsocialstructuremayeitherinfluenceordet
Earlyanthropologists,followingthetheorythatwordsdeterminethought,believedthatlanguageanditsstructurewereentirel
PeoplewhohaveInternetaccessathomearemorelikelytobeinarelationship,withtheWebgaininginimportanceasameetin
Abroadpublicdiscussionofenvironmentalproblemsbeganinthemid-1980s,whenthefirst"green"groupsformedinopposition
Whichofthefollowingregionsintheworldwillwitnessthesharpestdropinlifeexpectancy?
Thesuddendropintemperaturehasgreatly________thecrops.
Generallyspeaking,aBritishiswidelyregardedasaquiet,shyandconservativepersonwhois【C1】______onlyamongthosewith
Thesmallmountainvillagewas______bythesnowformorethanonemonth.
随机试题
切片(断层)厚度伪像产生的原因是
关于时间数列,下列论述正确的有( )。
下列关于无形资产摊销的表述不正确的有()。
()是深化教育改革,促进教育发展的先导。
要实现我国经济发展的战略目标,必须加快经济增长方式的转变,其核心是正确处理好()。
很早以前科学家就发现有些人对于某些药物的反应和其他病人不同。例如,某种麻醉用肌肉松弛剂会导致特定的人无法呼吸。后来,科学家发现产生这种现象的原因在于这类人拥有特定的基因。这也就带来了一个问题:研究人们之间的遗传差异是否可以促进医学发展出更高级的治疗手段,也
糖精:糖正确选项为()。
价值规律作用的实现有赖于
Completethenotesbelow.WriteONEWORDforeachanswer.PotterynotesEarthenwareadvantages:-po
A、Theyhavetoobeycertainrulesconcerningstudentconduct.B、Theyhavetodevotemoretimeonacademics.C、Apartmentsarever
最新回复
(
0
)