首页
登录
职称英语
An Interesting Phenomenon The ability of falling cats to
An Interesting Phenomenon The ability of falling cats to
游客
2023-12-20
25
管理
问题
An Interesting Phenomenon
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 adaptation by natural selection, but for physicists it bordered on the miraculous. Newton’s laws of motion assume that the total amount of spin of a body can not change unless an external torque speeds it up or slows it down. If a cat has no spin when it is released and experiences no external toque, it ought not to be able to twist around as it falls.
In the speed of its execution, the righting of a tumbling cat resembles a magician’s trick. The gyrations of the cat in midair are too fast for the human eye to follow, so the process is obscured. Either the eye must be speeded up, or the cat’s fall be slowed down for the phenomenon to be observed. A century ago the former was accomplished by means of high - speed photography using equipment now available in any pharmacy. But in the nineteenth century the capture 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 each, one from the side and one from behind, show a white cat in the act of righting it self. Grainy and quaint though 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 clockwise, the rear and tail twist counterclockwise, so that the total spin remains zero, in perfect accord with Newton’s laws. Halfway down, the cat pulls in its legs before reversing its twist and then extends them again, with the desired end result. The explanation was that while no body can acquire spin without torque, a flexible one can readily change its orientation, or phase. Cats know this instinctive ly, but scientists could not be sure how it happened until they increased the speed of their perceptions a thousand fold. [br] How did scientists increase "the speed of their perceptions a thousand fold" ?
选项
A、By analyzing photographs.
B、By observing a white cat in a dark room.
C、By dropping a cat from a greater height.
D、By studying Newton’s Laws of motion.
答案
A
解析
最后一段中间提到:Careful analysis of the photos reveals the secret,最后提到:but scientists could not be sure how it happened until they increased the speed of their perceptions a thousand fold.前后呼应,说明科学家是通过快速摄影并分析照片的“实验”来得出结论的。故答案应为A。
转载请注明原文地址:https://tihaiku.com/zcyy/3289795.html
相关试题推荐
Powermeansanabilitytodothingsandcontrolothers,togetotherstodo
Formethemostinterestingthingaboutasolitarylife,andminehasbeent
Researchersinvestigatingbrainsizeandmentalabilitysaytheirworkoffers
Researchersinvestigatingbrainsizeandmentalabilitysaytheirworkoffers
Researchersinvestigatingbrainsizeandmentalabilitysaytheirworkoffers
Beforeconsideringthisquestionitisinterestingtoreviewbrieflytheevo
Beforeconsideringthisquestionitisinterestingtoreviewbrieflytheevo
Beforeconsideringthisquestionitisinterestingtoreviewbrieflytheevo
Beforeconsideringthisquestionitisinterestingtoreviewbrieflytheevo
Beforeconsideringthisquestionitisinterestingtoreviewbrieflytheevo
随机试题
Manyanimalandevenplantspeciescommunicatewitheachother.Humansaren
[originaltext]M:IamsorelievedthatIjustfinishedthestoryIwasworking
Inancienttimesthemostimportantexaminationswerespoken,notwritten.I
检验检测机构涉及的采购服务至少包括()的相关内容。A、人员培训 B、委托采购
下列属于工程建设其他费的是()。A、建设单位管理费 B、生产家具购置费 C、
患者女,40岁。突然剧烈头痛、呕吐、眼睑下垂,见右眼球活动受限,呈外展位,瞳孔扩
劳动定额按制定方法可分为( )。A.经验估工定额B.统计定额C.类推比较定额D
劳动力市场四大支持系统包括()。A.就业体系 B.失业保险体系 C.劳动力的
下列各项中不属于商业贿赂行为的是( )。A.以明示的方式给对方折扣 B.在账
A.CD3 B.CD19 C.KIR D.MHC-Ⅱ E.IL-2树突状
最新回复
(
0
)