首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
专升本
A wind tunnel is used for testing planes or plane models. In a wind tunnel air is blown over a plane or a model placed in a test
A wind tunnel is used for testing planes or plane models. In a wind tunnel air is blown over a plane or a model placed in a test
admin
2010-01-08
19
问题
A wind tunnel is used for testing planes or plane models. In a wind tunnel air is blown over a plane or a model placed in a test section. Wind tunnel test sections are different in size depending on airflow speed requirements. Some low-speed tunnels have test sections large enough for a complete small plane. In the very high speed tunnels used for space testing, however, the model may be as small as a pencil.
There are two ways of feeding air to the test section. In the constant flow tunnel, airflow produced by electric fans is forced through the tunnel to the test section, then through another tunnel section back to the starting point for reuse. The other way involves storing high-pressure air in a box, sending it out by a controlling device to pass through the tunnel and test section into another box. This way is usually used for a very short period of high-speed airflow.
Wind tunnels are usually used to test planes before they are flown. Problems in a plane can be found when it meets the high-speed airflow in the tunnel. For example, if the wings are built so that they would weaken at high speeds, this fact can be discovered in the tunnel, thus saving many lives and millions of dollars.
In a wind tunnel, scientists also find out how different planes will act at different speeds. They find out such things as how the air dives by the wing surfaces, how slowly a plane can fly before it starts to drop, and how fast it can climb.
As mentioned in the last paragraph, a wind tunnel can be used to find out ______.
选项
A、how fast a plane can rise
B、how smooth a plane’s surface is
C、how a plane lands in a strong wind
D、how a plane drops at a low height
答案
A
解析
转载请注明原文地址:https://kaotiyun.com/show/MtvC777K
本试题收录于:
英语题库成考专升本分类
0
英语
成考专升本
相关试题推荐
Heoftenstoppedatthesoundofhisownstepsandwasafraidtolook______hisshoulder.
InCaliforniathenumberofhomesandbusinessesthathavelostpowerare______.MostCaliforniansthink______.
Somepeoplethinkthemoreexpensiveaproductis,thebetteritwillbe.(但事实并非如此).
Accordingtothepassage,thecomingofonlinejobsearchingbrings______.Accordingtothepassage,theInternethasrevoluti
Thisis______thelatestexampleofgovernmentinterference.
Modernformsoftransportationandcommunicationhavedonemuchto______theisolationoflifeinAlaska.
Movementfromoneracialroletoanotherusuallyinvolveslearningthesecretsofthenewstatus.
Whatmatters______notwinningbutparticipating.
Awindtunnelisusedfortestingplanesorplanemodels.Inawindtunnelairisblownoveraplaneoramodelplacedinatest
随机试题
某老年患者全口无牙颌进行义齿修复时发现左侧颊系带附着于牙槽嵴顶,影响将来齿固位。应该采用的治疗措施是
某企业2010年10月发生以下经济业务,根据下列经济业务编制会计分录。月末,计算本月车间使用的厂房、机器设备等固定资产应提折旧8400元,厂部使用的房屋、车辆等固定资产应提折旧1600元。
目前股票价格指数编制的主要方法不包括()。
已经掌握了“蔬菜”这个总括性的概念,再学习“萝卜”、“菠菜”等概念的学习属于()。
星期天早晨小丽陪爷爷出门散步,他们所走的路线为A—B—C—A,组成一个等边三角形ABC,如图所示,下列各项可以正确表示他们离A的距离S与时间t的函数图像是().
根据以下资料,回答116~120题。2008年1~2月县以下社会消费品零售总额比上年同期增长了()。
西方列强侵略中国是要把中国变成自己的殖民地,但是它们没能如英国在印度那样,对中国实行直接的殖民统治。它们中的任何一个国家无法单独征服中国,它们也不可能共同瓜分中国,其原因有()
A.ControlofRespirationB.BeautyofFreshCutFlowersC.RoleofRespirationD.MostImportantAspectofFlowerCareE.N
Somepioneeringworkthatbeganasanattempttodiscoverwaystoincreaseproductionefficiencyledtothefoundingofthehuma
We【C1】______upacamerafortheveryfirsttime.Wesnapsomepictures.【C2】______them,andletfamilymembersoohandaahover
最新回复
(
0
)