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
2024-02-14
7
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/3449759.html
相关试题推荐
[audioFiles]audio_eufm_j58_001(20082)[/audioFiles]A、Sheshouldfindaproperjo
【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
Iftheseclothesareproperlymerchandised,_____________(它们在圣诞节前应该相当好卖).theysh
Studentshavebeencomplainingmoreandmoreaboutstolenproperty.Radios,
Studentshavebeencomplainingmoreandmoreaboutstolenproperty.Radios,
Studentshavebeencomplainingmoreandmoreaboutstolenproperty.Radios,
Underproperconditions,soundwaveswillbereflectedfromahillsideorot
Underproperconditions,soundwaveswillbereflectedfromahillsideorot
Underproperconditions,soundwaveswillbereflectedfromahillsideorot
Underproperconditions,soundwaveswillbereflectedfromahillsideorot
随机试题
AcidRainHowever,manyadvantagesthe
分批法适用的生产组织形式是()。A.单件生产 B.成批生产 C.大量生产
应在燃烧室顶部的燃烧器上设有一对()。A.高温探测仪 B.火焰探测器 C
国家"十五"攻关缺血性心血管疾病发病风险的评估是目前常用的健康风险评估方法之一,
简述影响动作技能形成的因素。
基金销售机构包括()。 Ⅰ.中国证监会Ⅱ.商业银行 Ⅲ.证券公司Ⅳ.证券投
在弗洛伊德提出的人格理论中,本我、自我和超我所遵循的原则分别是()A.现实原则、
美国“文官条例”(1883年)
日常生活中,人们发现有的人天生嗅觉灵敏,运动能力强;有的人天生听觉发达,记忆力好
生活垃圾填埋场不得建在下列地区()。A.居民密集居住区 B.荒漠地区 C.
最新回复
(
0
)