首页
登录
职称英语
Under proper conditions, sound waves will be reflected from a hillside or ot
Under proper conditions, sound waves will be reflected from a hillside or ot
游客
2023-07-13
30
管理
问题
Under proper conditions, sound waves will be reflected from a hillside or other such obstruction. Sound travels at the rate of about one-fifth of a mile per second. If the hill is eleven hundred feet away, it takes two seconds for the sound to travel to the hill and back. Thus, by timing the interval between a sound and its reflection (the echo), you can estimate the distance to an obstruction.
During World War I1 the British used a practical application of this principle to detect German planes on their way to bomb London before the enemy was near the target. They used radio waves instead of sound waves, since radio waves can penetrate fog and clouds. The outnumbered Royal Air Force (RAF) always seemed to the puzzled Germans to be lying in wait at the right time and never to be surprised (袭击). It was radio echoes more than anything else that won the Battle of Britain.
Since the radio waves were used to tell the direction in which to send the RAF planes and distance to send them ( their range of flight, in other words), the device was called radio directing and ranging, and from the initials the word radar was coined. [br] The estimate is based on the______.
选项
A、direction of the hill
B、accepted speed of sound
C、interval between sound and echo
D、both B and C
答案
C
解析
从第一段最后一句我们可以找到答案:通过测定声音与它反射之间的间隙就可以测算与某一物体之间的距离,所以正确答案为C。
转载请注明原文地址:https://tihaiku.com/zcyy/2833493.html
相关试题推荐
Treesarearenewableresourcethatwhenmanagedproperlycan______ourneedsin
【B1】[br]【B11】A、downtownB、suburbsC、properD、districtsB根据后面同位语判断。后文也提示,20世纪50
Studentshavebeencomplainingmoreandmoreaboutstolenproperty.Radios,
Studentshavebeencomplainingmoreandmoreaboutstolenproperty.Radios,
Studentshavebeencomplainingmoreandmoreaboutstolenproperty.Radios,
Studentshavebeencomplainingmoreandmoreaboutstolenproperty.Radios,
Studentshavebeencomplainingmoreandmoreaboutstolenproperty.Radios,
Underproperconditions,soundwaveswillbereflectedfromahillsideorot
Underproperconditions,soundwaveswillbereflectedfromahillsideorot
Underproperconditions,soundwaveswillbereflectedfromahillsideorot
随机试题
Yourworkisgoodonthewhole,but______(仍然有改善的余地).thereisstillroomforimp
Wethinkitnecessary______.(让人们充分认识违反交通规则的危害)tomakepeoplefullyawareofthe
某工程每月所需混凝土量相同,混凝土用量为3200m3,计划4个月完成,混凝土综合
A.油细胞 B.油室 C.油管 D.树脂道 E.乳汁管党参的组织结构中有
关于模板拆除施工的做法,错误的是( )。 A、跨度3m的双向板,混凝土强度达
共用题干 AdultEducation1Voluntarylearnin
根据《中华人民共和国物权法》,抵押合同一般包括下列条款()。A.被担保债权的种
简述资源管理策略的种类。
判断糖尿病控制程度的指标是A.空腹血糖 B.糖基化血红蛋白 C.尿糖 D.
( )是发票管理的基础环节。A.发票印制管理 B.发票领购管理 C.发票开具
最新回复
(
0
)