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习题练习：Physics Unit12: Sound
本习题练习试卷来源于51fly国际课程 (https://51fly.win)， 为试卷打印版，您也可以在网站平台(https://autoconfig.51fly.win/)直接 访问本试卷的在线电子版并查看正确答案与解析，搜藏保存任意题目到收藏集。 访问方法: 平台首页左上角"通过试卷号快速访问"输入试卷号 70，并点击直达试卷；或浏览器地址栏内直接输入本试卷链接 https://autoconfig.51fly.win/test70.html  教师使用本平台可以抽题组卷或一键复制他人试卷，布置为在线考试或在线作业，全自动判分成绩一键排序导出，省时省力。
 作者: physics  发布日期: 2022-09-26 09:56    总分: 87分  得分: _____________

答题人: 游客未登录  开始时间: 22年08月07日 09:59  切换到: 整卷模式

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1#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Which of the following is a false statewewut w cka:9839f/l ement?

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2#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  In general, sound is conducted fastest throlnhm y;m3qciwcy5q;f+ j c/)2ugh

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3#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  What is the speed of sound in a st 2u+yu f7ecz9yeel rod?

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4#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  As the temperature of the air in2: xi,os*outhq:*s kp creases, what happens to the velocity of sound? (Assume that al s*:,*ui:sth2qkpooxl other factors remain constant.)

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5#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Compared to the velocitob1ktv.s vk+/zud h4 9v 4zqx,y of a 400 Hz sound, the velocity of a 200 Hz sound through aiuo+4 /1 txbdsqv4 ,k .zzvkvh9r is

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6#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Compared to the wavelength of a 400 Hz sound, the wavelengm bj1q:;olo y u-,5bmvth of a 200 Hz sound in :bulm o,bo;5my-j1vqair is

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7#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Sound vibrations with frequencies gre8ns -.al bjb9 ng.q0d3gzbd0fater than 20,000 Hz are called

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8#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Sound vibrations with frequency less than 5rtyhnf2filq esn;f,3 n6 *.j20 Hz are called

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9#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Suppose that a sound source is emqg5h / (cdtz2jitting waves uniformly in all directions. If you move to a point twice as far away from the tcg2 qd/hj5z( source, the frequency of the sound will be

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10#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  For spherically diverging wavesih d3jybz w7gnw e/3..08d xce, intensity is proportional to

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11#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The intensity of a point source at a distance d from the source is I. tue;71 (8s5sh4 a aeh ts eldp*awnz/(What is the intensity at a awzspa h eu4atn(5d (s l1*8;es/ te7hdistance 2d from the source?

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12#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  You double your distance from a souna613h.t8tuaz 0n ukxjd source that is radiating equally in all directions. What happens to the intensity of t txnhuaa j3z6.tku18 0he sound? It reduces to

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13#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  You double your distance from a sound source that is radiating0y.4*bytc; ay f d6jhe equally in all directions. What happens to the intensity le at4d;*.j6 beyycy 0hfvel of the sound? It drops by

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14#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Which of the following increases as a sound becomes lox0juv h6(v j,k ,w.stzuder?

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15#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  You move slowly toward a sh. b6ne5iv wyc+zf *f xbbe+/5peaker emitting a pure tone. What characteristic of the sound infc5 vzw/6bn.hf 5 by+e*+x beicreases?

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16#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  What determines "loudnesnez..0f1 yj4wpy(qvj s" of a musical note?

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17#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  What determines the "pitch" of a musical n5 oic2dt)p.ft nb 8x i,) 3kvwk:zkd;oote?

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18#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  When sound passes from air i)aime oi 0yag vn-u*b yu5mw+/ 4owx3*nto water

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19#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Pressure and displacement waves;ytfuxv0e 7r,namjz,e/6 s ;y are

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20#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Consider the standing wave on a guitar string anln wja 7t:xn,pr 9sr0,d the sound wave generated by the ,9wrrpt70,n xsljna : guitar as a result of this vibration. What do these two waves have in common?

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21#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  In a resonating pipe which is open at bot+( pibswkeyp9:fw.g0 : oz7zsh ends, there

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22#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Consider an open pipe of length L. What are the wavelengths of the three82:x 9o wnzwhzwlfo ) dcw1o4a5 *alp -jml;n; lowest tonex ow-z2jwdl;p 4m 1:zc5*hwl9n8a nw ;o lfoa)s produced by this pipe?

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23#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The lowest tone to resonate in an open pipe of length L is 200qbooh 1b yhz: )-qih,cdcx+g4y su1:0 Hz. Which one of the following frequencie b iqd +)0yox1: h4gbo-hsu:z1y,qchcs will not resonate in the same pipe?

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24#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  An open pipe of length L is resonatin 7k rq+wq(v 8:(ffyp ouu*g0urg at its fundamental frequency. Which statem8:g (r(ufpr0+ uu q7fovkqw* yent is correct?

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25#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  In a resonating pipe which is open at one end and closed at the other, thxq:jc;r h:)xxy;/uni c5n au;ere

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26#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Consider a closed pipe of length L. What are the wavelengths of the pvyzfw dvku c0-a132- three lowest tones produced by thiap -3f 2k dv0z1-vcywus pipe?

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27#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The lowest tone to re:)1yvm.sd j 3 dbp/muqfm+jw8sonate in a closed pipe of length L is 200 Hz. Which of the following frequencies wi fd 3qj mmv/ybp:8usm1).j+wdll not resonate in that pipe?

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28#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A pipe of length L closed at one3y.j nrkpu45e end is resonating at its fundamental frequency. Which statement is corrr4kj 5yp3u.ne ect?

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29#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A person stands between two speakers driven byx6bt j d)cw-*up9xdy c1i;w.p the same source. Each speaker produces a tone wtpc xby9j.-wi*u)16; c wddxpith a frequency of 200 Hz on a day when the speed of sound is 330 m/s. The person is
1.65 m from one speaker and 4.95 m from the other. What type of interference does the person sense?

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30#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  In order to produce beatgxfwi9 *-yjjxitk9dhz v6; +(y5)pjy s, the two sound waves should have

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31#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Two pure tones are sounded vo+ip vr+3rnw; x egax)5gy*1 together and a particular beat frequency is heard. What happens to t ow1*+r av);ig5+gyx3r nvxpehe beat frequency if the frequency of one of the tones is increased?

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32#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The Doppler shift explainst*r9fzelu il7tqz;6(g1y7h m

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33#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A sound source approaches a sts789bwnwuh70r b:b a:t875og bkb gpx ationary observer. The frequency heard by the observe7b:7 bo 8xbawk7gg :bst98hrwn5 up0br is

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34#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A sound source departs from a stationary ob( e3-s j7q rv:pe e5dco0s)nxo ib3e4qserver. The frequency heard by the oc3: qqend4 sx 0b - s)3(pjv7e5oreoeibserver is

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35#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  If a jet plane were to double its MACH-speed, its half-f0 bng// r dj7 y577bvr;4aqpfy00nneew np2bangle will decrease by a facbgb0 bp edf nn7yrq/0npw v7ra/ f7 e4yj0n52;tor of:

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36#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The speed of an ultrasof ,.t4d,rrjtoibi-- tnic sound of frequency 45 kHz in air is 352 m/s. What ist- ,iij trtfo,-4rb d. the air temperature?

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37#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  What is the ratio of the speed of s(c81lsw 0ozxn jybhdip 619 8round in air at $0 \; ^{\circ}C$ to the speed at $100 \; ^{\circ}C$?

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38#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  On a day when the speed of sound in air is 340 m; 4y3py1yj;vp3gq lcq /s, a bat emits a shriek whose echo reaches it 0.0250 s later. How far away was the object that reflected back the sounjq yc3y;4py;v 3pglq1d?

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39#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  You shout at a cliff, and hear the echo in 4.00 s. The temp54v, fa.tx ju:k1o banerature is $0 \; ^{\circ}C$. How far away is the cliff?

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40#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  If you hear thunder 5.0 s after6slg*j p,3cj w seeing a flash of lightning, the distance to the lightning stjc* 3pjw,sg6l rike is about

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41#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  An echo is heard 2.0 s from a cliff on a day t 2nbajfg)mzgv.79n ss0pc .8jhe temperature is $15 \; ^{\circ}C$. Approximately how far is the cliff from the observer?

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42#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  On a $30 \; ^{\circ}C$ day, there is an explosion. The sound is heard 3.4 s after seeing the flash. How far away was the explosion?

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43#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  You drop a stone into a deep well and hear t ieuneees7iopig,+) (o :.;p dhe splash 2.5 s later. How deep is the well? (Ignore air resistance, and assume the velocity of sioi.)pge 7o: peeieund( +;, sound is 340 m/s.)

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44#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The wavelength in air of a sound wave of frequency 500 Hz-fap rrtg 5d12 is

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45#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Sound traveling in aicy jbq vbz;b.g,vl.*5r at $23 \; ^{\circ}C$ enters a cold front where the air temperature is $2 \; ^{\circ}C$. If the sound frequency is 1500 Hz, determine the wavelength in the warmer air and in the colder air.

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46#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  What is the intensity level of av/uzs)5.nbb g).fn er sound with intensity $10^{-3} \; W/m^{2}$?

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47#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  What is the intensity of a 70-dB soune;w e27f gbcv:d?

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48#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  What is the ratio of the intensities of two sx7,w5np -uonk/a *3mfh+ k ma/ih)zwrounds with intensity levels of 70 dB and 40 n- 3w*7h+a zauwn,fo5mkx/km) p ihr /dB?

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49#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The intensity level by 15 a0rsmo5s+t l. engines in a garage is 100 dB. What is the intensity level generated by ons sl0m+5a.r ote engine?

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50#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The intensity at a da0xl id19mw+p6tn a 5nistance of 6.0 m from a source that is radiating equally in all +a p5iltd x nn196m0awdirections is
$6.0 \times 10^{-10} \; W/m^{2}$. What is the power emitted by the source?

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51#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The intensity at a distance of 6.0 m from a source that is radiating eqft6+:xdd ye* cf/efa8ually in all directio edat*fe : f+/xc8ydf6ns is
$6.0 \times 10^{-10} \; W/m^{2}$. What is the intensity level in dB?

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52#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A barking dog delivers about 1 mW of power, whi ;mm )8tcntrd7ch is assumed to be uniformly distributed in all directions.m; ctd7m)t 8nr What is the intensity level at a distance 5.00 m from the dog?

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53#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The intensity level is 65 dB at a dist 176k6 hw7u zv(dlpnnrance 5.00 m from a barking dog. What would be the intensity level if two identical dogs very close to each7lk nhpr 1(d7 zwvn6u6 other are barking?

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54#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  At a distance of 15 m from a sound source the intensity leveli5w,6 *u zm; j6ozbastna,m.l is 60 dB. What is the intel wa ju5*.6,z6zsbm,atoimn;nsity level (in dB) at a point 2.0 m from the source? Assume that the source radiates equally in all directions.

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55#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The sound intensity level 5.0 m from a point source is 95 dB. At what distshjb7eh x* ..wance will it b7e.h. xbjhs*w e 75 dB?

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56#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The third harmonic of a complex tone h;i f/ cq;ed8 3v,zfm 0wc(cukpkvz*:las a frequency of 1200 Hz. What is the frequency of the fourth harmowckzl fd8vq/fc:( 3ke v;ic;z ,*p0 umnic?

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57#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The frequency of the third harmonic of an open pipe gxn:o,n3d so(is 900 Hz. What is the lengt,no s3(dox:gn h of the pipe?

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58#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The lowest tone to resonate in an open pipe of length L is 40eomhdo, meblso 2;4840 Hz. What is the frequency of the lms84lmdo 2 o;ehobe4,owest tone that will resonate in an open pipe of length 2L?

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59#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  An organ pipe open at both ends has a 2b+tn 8baru9m length of 0.80 m. If the velocity of sound in air is 340 m/s, what is tm9 nb8brut +a2he frequency of the second harmonic?

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60#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A 3.00-m long pipe is in a room where the temperaturk(aj 3kp;2hcllu u+ .ze is $20 \; ^{\circ}C$. What is the fundamental
frequency if the pipe is open at both ends?

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61#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The fundamental frequency in a bfk hl)r 6iyr4g0j/)vz6xb)n pipe closed at one end is 330 Hz. What is the frequency of the third harmonic?)6nkig v yrjz0)/ bfl 46bhx)r

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62#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  What is the length of the shortk9dtnc f6xq/svve0afr 3;u 7 /est pipe closed on one end that will have a fundamental frequency of 60 Hz on a day whenv6uqxdek r9c f7 /vst30/fna ; the velocity of sound is 340 m/s?

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63#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A 3.00-m long pipe is in a room where the temperatl/z4epc*-vt qqyrw ; 4ure is $20 \; ^{\circ}C$. What is the fundamental frequency if the pipe is closed at one end?

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64#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A 3.00-m long pipe is in a room where thes3tzs/8h rh,zzjyc/pqm04k ( temperature is $20 \; ^{\circ}C$. What is the frequency of the second harmonic if the pipe is closed at one end?

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65#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A closed organ pipe of lengtn :t5 zlzpq r85g-09q+ mrblw8zz2bith 0.75 m is played when the speed of sound in air is 340 m/s. Wha-zbi+5bn 5r tlz8qtqlp90rz mgw: 8 2zt is the fundamental frequency?

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66#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Consider two pipes of the same length: one is hwbzwgl u1 8-q .8cer:open and the other is closed on one end. If the fundamental frequency of the open pipe is 300 Hz, what is the fundamental frequency of the closed pipbhgwle 1zc 8r.u-:qw 8e?

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67#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Two adjacent sources each emit a frequency of 800 Hz in air where thme8w1q cu8kxi3z t) *ye velocity of sound is 340 m/s. How much farther back wmcw 38 zx) *yku1eq8itould source 1 have to be moved so an observer in front of the sources would hear no sound?

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68#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Two speakers are placed side by side and dri; .k 7mkchv3oru 5c24 ome,tsaven by the same frequency of 500 Hz. If the distance from a person to one speaker is 5.00 m and the person detects little or no sound, which of the following is a possible the distanc7;kov4o te,ack2u5 .hrmscm3e from the person to the other speaker? (The sound speed is 340 m/s.)

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69#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Two tunes have frequencies of 440 Hz and 444 Hz. What is the b/+aahe, j(3tyzjyhr +qc( ej 9eat frequency?

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70#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A music tuner uses a 550-Hz tuning fork to .e -nc54fvj po6znj)ltune the frequency of a musical instrument. If the tuner hears a beat -.vejcn6 p ) l45jzonffrequency of 2 Hz, what is the frequency of the instrument?

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71#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The wavelengths of the sounds producemsk kck1( nrzi kb x;ai2;/ wy,hv)u+ *fh3a6nd by two horns are 6 m and 7 m respectively. What beat frequency is heard when the horns are sounded on a day when the velocity x/auzr m 6 1s;ci;b(i2an3kfv),h+kkk hny *wof sound is 340 m/s?

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72#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The corresponding violin strings on two violins in an orp (v, ry.gu2ng/6g7b;p edf uechestra are found to produce a beat frequency of 2 Hz when a frequency of 660 Hz is played. What percentage change in the tension of one of the stringgdepg ( uuny62, /.7gfbv ;reps would bring them to the same frequency?

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73#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  An observer approaches a stationaryv+9vd. vz6ok4 cr8 spp)t5yu e 1000-Hz sound source at twice the speed of sound. The observer hear48r d 6v)u5p vksyvpzo9te.c +s a frequency of

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74#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A sound source (normal frequency of 100f+ /eg-d;u mjduekc)u; fyw (bgz )-3i0 Hz) approaches a stationary observer at one-half the speed of sound. The observer hears a /uf)gujdkm-de;-3f ;b guy e+wcz()i frequency of

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75#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A sound has a frequency of 1000 Hz. If a listener moves with a speed of 307zx8 h :i itcbfsgod1ee/hu5ah6)h+/ m/s away from the source, what is the frequency heard by the observer? (The sound speed 7oa/s d 5c)hu8bt ex :ghe/i fih6zh1+is 340 m/s.)

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76#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A police car has an 800-Hz siren. It is traveli 5hk pc1u5;j5x1o)tswcg.cm z ng at 35 m/s on a day when the speed of sound through air is 340 m/s. The car )uhp o;c151w5t sgkmcj.zxc5approaches and passes an observer who is standing along the roadside. What change of frequency does the observer hear?

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77#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  What is the frequency e iigyqi6- dt);yd a laqh) (vj91o7q+heard by a stationary observer when a train approaches with a speed of 30 m/s. The frequency of the train horn is 600 Hz and the speed of sound is 34-;+ )7v9 6oi)aqqj igdl yiq dh(1eaty0 m/s.

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78#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A train is traveling toward yzq rax-8 0i y:.:ihkxh;gl)ddg8 v ,yyou at 120 km/h. The train blows its 400-Hz whistle. Take the speed of sound to be 340 m/s. W.g8 :y xg;-,r8qyx ylkv: i0a)hdidzhhat frequency do you hear?

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79#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  You are moving at 120 km/h toward a stati x+o. m9b;efkjonary train. The train blows its 400-Hz whistle. mejb+9xk. ;of Take the speed of sound to be 340 m/s. What frequency do you hear?

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80#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A train is traveling away from you at 120 km/h. The train blows its 400-Hz whisdptlvlcl; ;lmvud,x x0v hh*;:6 9 r7jj)do i.tle. Take the speed ovu6dlpt;*j ivd.jr9 0x; oh;mhd:l7clvl) x,f sound to be 340 m/s. What frequency do you hear?

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81#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A train is traveling away from you at 120a xnmv,*iz3/a km/h. It blows its whistle, and you hear a tone of 400 Hz. Take the speed of sound to be 340 m/s. What is the actual frequency of the *na,vz3a x/i mwhistle?

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82#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The frequency of a train horn is 500 Hz. Assume the ik n8fx -/qu j nk.gd7 -:uf/zhlqv;*uspeed of sound in air is 340 m/s. What is tun.f 7vh*uk-ng8jidufk//- xzq l:; qhe frequency heard by an observer if the observer is moving away from the train with a speed of 30.0 m/s?

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83#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The frequency of a train horn is 500 Hz. Assume the nk .dw*4kv9 z1/e5-cnpyutik speed of sound in air is 340 m/ 4/e1-inc ktkd5z*uy. 9kwpnvs. What is the frequency heard by an observer if the observer is approaching the train with a speed of 30.0 m/s?

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84#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Sonar is used to determine the speed of an object. A 40-kHz sig c uup5o/*g*rm lpc+/hnal is sent out, and a 42-kHz u ro c5p/+m**chg/u lpsignal is returned. Assume the speed of sound is 345 m/s. How fast is the object moving?

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85#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The half angle of the concrw)22wvgc05 7ei ar50xb*7mx7 o dm3cc onowical shock wave produced by a supersonic aircraft is $60^{\circ}$. What is the Mach number of the aircraft?

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86#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A jet flies at a speed of Malpymw) 1t:f89 1ub6ijzy*zuk ch 1.4. What is the half-angle of the conical shock wave foju *iyz6:) f9uwb ml1y8t zk1prmed?

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87#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The Concord airplane flies from the United States to Europe w uy-epas7ik 27ith a Mach number of 1.05 where e u7piysk-2 a7the air temperature is $5.0 \; ^{\circ}C$. What is the speed of the plane?

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