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
37
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] 【C15】
选项
A、in order that
B、so that
C、as long as
D、because
答案
B
解析
转载请注明原文地址:https://tihaiku.com/zcyy/3204572.html
相关试题推荐
Manyofthesuccessfulmen,hadtheybeenabletochooseforthemselves,wouldh
Todevelop______,totrainthemselvestobehavelogicallyandtruthfully,andto
Animalsthatcouldnot_________themselvestothechangedenvironmentperisheda
1Sincetheearly1930s,Swissbankshadpridedthemselvesontheirsystemof
Dreamsare__________inthemselves,but,whencombinedwithotherdata,theyca
Inancienttimespeoplewhowerethoughttohavetheabilityto________dreams
[originaltext]Inadditiontothesegeneralthreatstostabilityandsecuri
Noonecandenythatpesticidehaveimprovedtheabilityoffarmerstobrin
Noonecandenythatpesticidehaveimprovedtheabilityoffarmerstobrin
Noonecandenythatpesticidehaveimprovedtheabilityoffarmerstobrin
随机试题
NorthernEuropeansarewillingtopayalotofmoneyandputupwithalotofin
InMarch300collegestudentsturnedoutinWashingtontoprotestagainstpropos
C
下列有关计算机构成及性能的表述中,不正确的是()。A.目前,电子计算机的发展已
某精细化工项目,业主委托招标代理机构采用邀请招标方式采购设备。招标过程中,发生如
1998-149.黄连、黄柏同用的方剂是 A.乌梅丸B.枳实消痞丸C.木香
听莫扎特的音乐能提高智商,被称为“莫扎特效应”。无论“莫扎特效应”有无这样的神奇
不良个人住房贷款催收的方式包括()。A:上门催收B:法律手段催收C:电话催收
在露天矿工程中,影响边坡稳定的主要因素有()。A.稳定性系数 B.地质构造条件
子宫内膜癌确诊依靠( )。A.子宫输卵管碘油造影检查 B.B型超声检查 C
最新回复
(
0
)