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
外语
If a mother pushes her small son in a swing, giving only a light force each time he returns, eventually he will be swinging quit
If a mother pushes her small son in a swing, giving only a light force each time he returns, eventually he will be swinging quit
admin
2012-12-26
36
问题
If a mother pushes her small son in a swing, giving only a light force each time he returns, eventually he will be swinging quite high. The child can do this for himself by using his legs to increase the motion, but both the mother’s push and the child’s leg movements must occur at the proper moment, or the extent of the swing will not increase. In physics, increasing the swing is increasing the amplitude; the length of the rope on the swing determines its natural oscillation period. This ability of an object to move periodically or to vibrate when stimulated by a force operating in its natural period is called resonance.
Resonance is observed many times without consciously thinking about it; for example, one may find an annoying vibration or shimmy in an automobile, caused by a loose engine mount vibrating with increasing amplitude because of an out-of-round tire. The bulge on the tire slaps the pavement with each revolution; at the natural resonance point of the engine mount, it will begin to vibrate. Such vibrations can result in considerable damage, if allowed to persist. Another destructive example of resonance is the shattering of a crystal goblet by the production of a musical tone at the natural resonant point of the goblet. The energy of the sound waves causes vibration in the glass; as its amplitude increases, the motion in the glass exceeds the elasticity of the goblet, and it shatters.
An instrument called a tachometer makes use of the principle of resonance. It consists of many tiny bars, loosely fastened together and arranged so that each bar can slide independently of the others. Movement of the bars causes changes in a dial. When placed next to a rotating motor or engine, the tachometer picks up slight vibrations which are transferred to the resonant bars. These bars begin to move, and the resulting dial may be read to find the revolutions per minute of the motor very quickly. (328 words)
An object, if moving rhythmically when stimulated in a natural period, is said to______
选项
A、vibrate
B、resonate
C、swing
D、oscillate
答案
B
解析
根据文章第一段最后一句“This ability ofan object to move periodically or to vibrate when stimulated by a force operating in its natural period is called resonance.”可知,物体受到一 种以其自然周期运动的外力刺激时,它就会周期性的运动或振动,这种能力被称为共振。据 此判断,答案是B。
转载请注明原文地址:https://kaotiyun.com/show/zD9O777K
0
考博英语
相关试题推荐
Theirexperimentsshowthatthe______strainofwheatgrowsmorequicklyandisresistanttodisease.
ThecrucialyearsoftheDepression,astheyarebroughtintohistoricalfocus,increasinglyemergeasthedecisivedecadeforA
Tobesure,therewouldbescarcelynotimeleftoverforotherthingsifschoolchildren______allsidesofeverymatteronwh
Anyonewhodoubtsthatchildrenarebornwithahealthyamountofambitionneedspendonlyafewminuteswithababyeagerlylea
Forgatheringdataaboutindividualsorgroupsatdifferentdevelopmentallevels,researcherscanusetwo.relatedresearchdesi
Criticalarticlesonthisnovelarguethatthoughtheplotseemslogical,theendingofthenovelis______.
Thebook,published______,revivedourinterestintheauthorwhohadjustdied.
Amanagerwhotakesabsolutecontrolofaworkplacesituation,withoutreferencetotheirteam’sviewsandinput,wouldbeexhib
Inasmuchasayeardoesnotelapsewithoutacertainnumberofvillagersfallingvictimtotheferocityoftiger,itsroaris__
NationalGeographic【61】fillanumberofroles,saysKarenKasmauski."Wearejournalists;researcher,thinkers,"shesays,"phot
随机试题
2013年3月,A公司与B公司签订了一份购买设备的合同,标的额为500万元。该合同约定:A公司于3月10日向B公司支付50万元作为预付款;B公司于4月10日交付设备;A公司于B公司交付设备验收合格之日起3日内付清货款;任何一方违约,应当向守约方支付标的额
驾驶机动车在这个时候要减速慢行。
已知椭圆的参数方程为,求其在t=π/6处的切线方程.
上消化道大出血伴休克时首选的护理措施是()。
某道路运输企业共有基层员工83人,管理人员15人。依据《安全生产法》的规定,下列关于该企业安全生产管理机构设置和安全生产管理人员配备的说法,正确的是()。
按照《城市公共厕所设计标准》的规定,下列有关公共厕所平面设计的叙述中,正确的是()。
导游人员服务水平的高低会影响旅游产品的销售。()
由曲线y=x3-2x2+x+2与x轴所围成平面图形的面积为()。
BSP方法建立数据类与过程的关系通常是利用______。A)过程/组织矩阵B)U/C矩阵C)系统/数据库矩阵D)系统/数据类矩阵
Sportsisoneoftheworld’slargestindustries,andmostathletesareprofessionalswhoarepaidfortheirefforts.Becausean
最新回复
(
0
)