首页
登录
职称英语
[originaltext] The idea of fighting a noise by making more noise sounds stra
[originaltext] The idea of fighting a noise by making more noise sounds stra
游客
2023-09-01
64
管理
问题
The idea of fighting a noise by making more noise sounds strange, but that’s exactly what motor engineers are doing in Germany and some other countries.
Carmaker’s research and development laboratories have already proved that mixing in more noise with the help of loudspeakers can reduce the unwanted noise.
Physicists have known about the technique for a long time. Sound is made up of pressure waves in the air. If two sound waves of the same frequency mix so that the highest point of one wave happens at the same time with the lowest point of the other wave, the result is no sound. Therefore, by producing a perfect copy of the noise and delaying it by half a wave cycle, we can kill the unwanted noise. Using this technique many carmakers are racing to develop noise-killing systems both inside and outside the cars.
Another good thing about the use of noise-killing systems is that it saves the need for a silencer, which not only reduces the weight of a car, but also makes the motor burn less oil and work better.
Some engineers believe that the noise-killing system will be used in most cars in 1996. But the carmakers haven’t decided if they will put it into production because it would add several hundred dollars to the cost of their cars.
选项
A、Reduce the cost of a silencer.
B、Make a silencer unnecessary.
C、Improve the performance of a silencer.
D、Make a car quieter.
答案
B
解析
转载请注明原文地址:http://tihaiku.com/zcyy/2976369.html
相关试题推荐
[originaltext]M:Hi,Allison.How’sitgoing?W:Busy!I’vebeenbusywithmyin
[originaltext]M:Hi,Allison.How’sitgoing?W:Busy!I’vebeenbusywithmyin
[originaltext]M:Hello,er...isthistheaccommodationoffice?W:Yes,howcanI
[originaltext]M:Hello,er...isthistheaccommodationoffice?W:Yes,howcanI
[originaltext]W:Excuseme.I’mafraidI’mabitlost.I’mlookingforthelibr
[originaltext]W:Excuseme.I’mafraidI’mabitlost.I’mlookingforthelibr
[originaltext]W:Excuseme.I’mafraidI’mabitlost.I’mlookingforthelibr
[originaltext]W:Excuseme.I’mafraidI’mabitlost.I’mlookingforthelibr
[originaltext]Didyoueverwonderwhathappenswhensomethingfunnyhappens
[originaltext](30)IfyouhaveeverdriveninLosAngeles,youknowthatpeop
随机试题
ABush’sLegacy(Ⅰ)布什的遗产(Ⅰ)PresidentBusharrivedinWa
He______fromthebridgeandrescuedthedrowningboy.A、diedB、divedC、divided
D TheRedCrossisaninternationalorg
A. B. C. D.
价格领导形式通常包括( )。A.成本最高型价格领先 B.支配型价格领先 C.
A.乳房有周期性疼痛 B.肿块边界清楚,表面光滑、增长缓慢 C.肿块大、活动
某商品按20%的利润定价,然后打八折出售,结果亏损200元。这种商品的成本多少元
A. B. C. D.
以下不属于启动阶段行业特点的是( )。A.企业管理者缺乏行业经验 B.发展迅速
下列向发包人进行工期与费用索赔的说法,正确的是( )。A.延期发出施工图纸产生的
最新回复
(
0
)