题库网 (tiku.one)

 找回密码
 立即注册

 

      

上传图片附件

未使用图片

小贴士: 允许的图片文件格式为: gif, jpg, jpeg, png, webp,上传完成后会在上方生成预览,用鼠标连续双击缩略图,或拖动缩略图,该图片就被绑定至本题,显示在题目下方

本次作答已使用

小贴士: 此栏目显示的是当前作答使用的所有图片,绑定到某一题目的图片同时会显示在该题目下方; 删除使用的图片会将其转移到<未使用图片>类别


习题练习:gc textbook chapter 12 Sound

 作者: admin 发布日期: 2025-02-02 21:19   总分: 110分  得分: _____________

答题人: 游客未登录  开始时间: 25年01月19日 20:51  切换到: 整卷模式

标记此题
1#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
What is the evidence that sound travels as a wave?fkj(wv +x9s/i4qah/x
参考答案:    

标记此题
2#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
What is the evidence that sounwva/1 ll cr/ep4 2,hjsd is a form of energy?
参考答案:    

标记此题
3#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
Children sometimes play with a homemade “telephone” by attaching tp51)nseu /vj a string to the bottoms of two paper cups. When the string is strj5st /u1) evnpetched and a child speaks into one cup, the sound can be heard at the other cup (Fig. 12–29). Explain clearly how the sound wave travels from one cup to the other.
参考答案:    

标记此题
4#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
When a sound wave passes from b5y14*qq z/o va:xs bgair into water, do you expect the frequency or wavelength tooxqaz:/g4b vby s 51*q change?
参考答案:    

标记此题
5#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
What evidence can you give that the speed of sound in air does not depend sib)wnd;gnb)jre5(v ,v gnifib;,g(nvbv r5nj)w )decantly on frequency?
参考答案:    

标记此题
6#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
The voice of a person who has inhaled helium sounds very high-pitched. Whgldlpb- i6.*iy?
参考答案:    

标记此题
7#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
How will the air temperature v8y 1,mjwka c2in a room affect the pitch of organ pipes?
参考答案:    

标记此题
8#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
Explain how a tube might be used as a filter to redu*fe jn/ass oj8kr5c* -w;lb/uce the amplitude of sounds in various frequency ranges. (An example is a car 5eo 8fr s-nkblaj/c/;** swuj muffler.)
参考答案:    

标记此题
9#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
Why are the frets on a guitar (Fig. 12–30) spaced closer togethe x2n*zwdg:-yz9h w8 r/bx apl1hw/g,er as you move up the fingerboard toward thb z*,r zy-h/8d9wa 1g:xw 2nhle/pxgwe bridge?

参考答案:    

标记此题
10#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
A noisy truck approaches you from behind a bu+kis1e 7n +bchilding. Initially you hear it but cannot see it. When it emerges and you do see it, its sound is suddenly “brighter” — you hear more of +7 cnhsb1 +ekithe high-frequency noise. Explain. [Hint: See Section 11–15 on diffraction.]
参考答案:    

标记此题
11#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
Standing waves can be said to be due to “intq r br,acej;) ;r8cg v-nt.vp+erference in space,” whereas beats can be s ,t;crrp c8va-)en;+ qb. rjvgaid to be due to “interference in time.” Explain.
参考答案:    

标记此题
12#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
In Fig. 12–16, if the frequency of the speakers were lowered, would the poin2hqd4ags a32 nts D and C (wn3 qs4da agh22here destructive and constructive interference occur) move farther apart or closer together?
参考答案:    

标记此题
13#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
Traditional methods of protectinabrmob f r4p1 kjpbw;;, 4h7y(g the hearing of people who work in areas with very high noise levels have consisted mainly of efforts to block or reduce noise levels. With a relatively new technology, headphones are worn that do not block the ambient noise. Instead, a device is used which detects the noise, inverts it electronically, then feeds it to the headphones in addition to the ambient noise. How could adding more noise reduce the(b7rbpyw;4 af m,rj4ob1hk p ; sound levels reaching the ears?
参考答案:    

标记此题
14#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
Consider the two waves shown in Fig. 12–31. Each wave can be thought of as a sui-;.2a. jc,lj jd iuhjperposition of two sound wjj,.liju h2c .i-dj;aaves with slightly different frequencies, as in Fig. 12–18. In which of the waves, (a) or (b), are the two component frequencies farther apart? Explain.
(12-31)
(12-18)
参考答案:    

标记此题
15#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
Is there a Doppler shift if the sourceo694i2 z hvdrh*uv1ip and observer move in the same direction, with the same velocity? u2* hhi9p1ov6i rv zd4Explain.
参考答案:    

标记此题
16#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
If a wind is blowing, will this alter the frequency of the sound heard by a p** 7 crmyx70bawwmr5,n /lbq cerson at rest with respect to the source? Is the wavelength or velocity chan70ymw5cb m r, w/7*q*bcx anrlged?
参考答案:    

标记此题
17#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
Figure 12–32 shows various positions of a child in motion on a swing. A moni+f(0ljtc1 e aiw3lf(g*rff8 g tor is blowing a whistle in front of the child on the ground. At which position, A through E, will the child hear the highest frequency for the soundwae8j f (cg1fl+ gft 0(r3l*fi of the whistle? Explain your reasoning.

参考答案:    

标记此题
18#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A hiker determines the length of a lake by listening for the echo of hjgfj)j cz/- q+er shout reflected by a cliff at the far ezcjf q/j+gj)- nd of the lake. She hears the echo 2.0 s after shouting. Estimate the length of the lake. $\approx$    $ \times10^{ 2}$m

参考答案:     查看本题详细解析

标记此题
19#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A sailor strikes the side of his ship just below the waterline. He hearsr6 86o vu,oaiw the echo of the sound reflected from the ocean floor directly below 2.i,vu or 866woa5 s later. How deep is the ocean at this point? Assume the speed of sound in seawater is 1560 m/s (Table 12–1) and does not vary significantly with depth.    $ \times10^{ 3}$m

参考答案:     查看本题详细解析

标记此题
20#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  (a) Calculate the wavelengths in air a / 8wl:5uarknjt 20 $^{\circ} $ C for sounds in the maximum range of human hearing, 20 Hz to 20,000 Hz. $\lambda_{20Hz}$ =    m $\lambda_{20kHz}$ =    $ \times10^{-2 }$ m(b) What is the wavelength of a 10-MHz ultrasonic wave?    $ \times10^{ -5}$m

参考答案:     查看本题详细解析

标记此题
21#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  An ocean fishing boat is drifting j v3c2derp7qfk74t n4j2gh rm/ fdcu* 0ust above a school of tuna on a foggy day. Withou pn342hk/qrtmf 2udcf dgcrj4*7e 70vt warning, an engine backfire occurs on another boat 1.0 km away (Fig. 12–33). How much time elapses before the backfire is heard (a) by the fish,    s (b) by the fishermen?    s


参考答案:     查看本题详细解析

标记此题
22#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A stone is dropped from the top of a cliff. The splash it makes w jb4(+ 8 wrjope.4iuxwhen striking the water below is heard 3.5 s later. How high is the cli+w8xjji4w 4opb(eu .rff?    m

参考答案:     查看本题详细解析

标记此题
23#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A person, with his ear to the ground, sees a heu jidu ;o;;d6uge stone strike the concrete pavement. A moment later two sounds are heard from the impact: one travels i;i; d;dou uej6n the air and the other in the concrete, and they are 1.1 s apart. How far away did the impact occur? See Table 12–1.$\approx$    $ \times10^{2 }$m

参考答案:     查看本题详细解析

标记此题
24#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Calculate the percent error made osio3skl2 v-o-(xz x(rtqr p(+ver one mile of distance by the “5-second rule” for estimating the distance from a lightning strike if the temperature is (a) 33qt(p-(+ voxz i oxsl srr-k2(0 $^{\circ} $ C, $\approx$    % (b) 10 $^{\circ} $ C$\approx$    %.

参考答案:     查看本题详细解析

标记此题
25#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  What is the intensity of a sou5, rz;(t3c )f tk dvvmmg9l.vwnd at the pain level of 120 dB?    W/$m^2$Compare it to that of a whisper at 20 dB.    $ \times10^{-10 }$W/$m^2$

参考答案:     查看本题详细解析

标记此题
26#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  What is the sound level of a sound whoanq;*c ; g4cue 5zu7djse intensity is $2 \times10^{ -6}W/m^2$?    dB

参考答案:     查看本题详细解析

标记此题
27#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  If two firecrackers prz ,uc8ecxm8rn1:mhi91pf n m, oduce a sound level of 95 dB when fired simultaneously at a certain place, what will be theue 1cmmhn,i,m9c8:rx8p z nf1 sound level if only one is exploded? [Hint: Add intensities, not dB’s.]    dB

参考答案:     查看本题详细解析

标记此题
28#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A person standing a certain distance from an airplane with four2. rcc2py0fnr equally noisy jet engines is experiencing a sound level bordering on pain, 120 dB. What sound level would this person experience if the captain shut down all but one engine? [Hint: Add intensities, not dB’2fpcr2rc. y0ns.]    dB

参考答案:     查看本题详细解析

标记此题
29#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A cassette player is said to have a signal-to-noise ratio of 58j+05a yo . 5p98gfzqlri7eyk h dB, whereas for a CD p7 .jih9+f y5akp05lgzyqoe 8rlayer it is 95 dB. What is the ratio of intensities of the signal and the background noise for each device? 58 dB =    $ \times10^{ 5}$ dB =    $ \times10^{9 }$

参考答案:     查看本题详细解析

标记此题
30#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  (a) Estimate the power output of sound w h)gydi ,+pqgjtx2mq6gu( .3from a person speaking in normal conversation. Use Table 12–2. Assume the sound spreads roughly uniformly over a sphere centered on twp j .x6y+g(qm)q ug,gdt 2ih3he mouth. $\approx$    $ \times10^{ -6}$W(Round to the nearest integer)
(b) How many people would it take to produce a total sound output of 100 W of ordinary conversation? [Hint: Add intensities, not dB’s.]$\approx$    $ \times10^{7}$people

参考答案:     查看本题详细解析

标记此题
31#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A 50-dB sound wave strikes an eardffg7d7e*; mu(7,u 2zyum/atvi xpxp+rum whose area is $5 \times10^{ -5} m^2$ (a) How much energy is absorbed by the eardrum per second?    $ \times10^{-12}$W (b) At this rate, how long would it take your eardrum to receive a total energy of 1.0 J?   $ \times10^{ 3}$yr

参考答案:     查看本题详细解析

标记此题
32#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Expensive amplifier A is rated at 250 W, whilwfsyaz *;k6pm r1e r:4++zqote the more modest amplifier B is rated at 40 W. (a) Estimate the sound level in decibels you would expect at a point 3:+t ezw +przofk y*4msar 61q;.5 m from a loudspeaker connected in turn to each amp.$I_{250}$ =    dB $I_{40}$ =    dB (b) Will the expensive amp sound twice as loud as the cheaper one?

参考答案:     查看本题详细解析

标记此题
33#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  At a rock concert, a dB meter registehqip*usa7b:q8t c )e(red 130 dB when placed 2.8 m in front of a l hat*p:ibs(e8c q) 7uqoudspeaker on the stage.
(a) What was the power output of the speaker, assuming uniform spherical spreading of the sound and neglecting absorption in the air?$\approx$    $ \times10^{2 }$W(“Round to one decimal place)
(b) How far away would the sound level be a somewhat reasonable 90 dB?   $ \times10^{2}$m

参考答案:     查看本题详细解析

标记此题
34#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Human beings can typh+j-22 zdot)ck ckj 3tically detect a difference in sound level of 2.0 dB. What is the ratio of the amplitudes of two sounds whose leveljtk+-2 ckhtc d)j 3zo2s differ by this amount? [Hint: See Section 11–9.]$\approx$   

参考答案:     查看本题详细解析

标记此题
35#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  If the amplitude of a sound wave is tripled, (a) by what factor wved7cikt p7gqj83cqu a12+l .ill the intensity increase? Increase by a facdic pjtu+7 a731k 2vegqq.l c8tor of    (b) By how many dB will the sound level increase?    dB

参考答案:     查看本题详细解析

标记此题
36#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Two sound waves have equal displacement w- ig.usp daz71; v- dd,j:ruramplitudes, but one has twice the frequency of the other. What is the ratio of their intensit i-pj1r-wud,7a srg.duz : v;dies?   

参考答案:     查看本题详细解析

标记此题
37#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  What would be the sound levellsir 16e-+3-9*bqhzh x uj idm (in dB) of a sound wave in air that corresponds to a displacement zlh3 qd h rs+6m9ue-1bi-x*ji amplitude of vibrating air molecules of 0.13 mm at 300 Hz?    dB

参考答案:     查看本题详细解析

标记此题
38#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A 6000-Hz tone must hay,k 6qqu zv2:sog 63mkve what sound level to seem as loud as a 100-Hz tone that has a 50-dB sound level? (See Fm v:zkqk6osg 2qy u63,ig. 12–6.)    dB


参考答案:     查看本题详细解析

标记此题
39#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
What are the lowest and highest frequencies thak) qraw)nkx 9ul 4ia31t an ear can detect when the sound levelqlrkki u ax)w493 1)na is 30 dB? (See Fig. 12–6.)

参考答案:    

标记此题
40#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Your auditory system can accommodate a huge range of so7x+ j),synaccn rdl6) und levels. What is the ratio of highest to lowest inten sl)r,y7ncxcd+6aj n )sity at
(a) 100 Hz,$ \times10^{ a }$ a =   
(b) 5000 Hz? $ \times10^{ a }$ a =   
(See Fig. 12–6.)



参考答案:     查看本题详细解析

标记此题
41#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The A string on a violin has a fundamental frequency of 440 Hz. Tz-cb 9)matwbc4/ rs9hzk3h *ahe length of the vibrating portion is 32 cm, and it has a mass of 0.35 g. Under what tension must the string be pla*/h zbs tz)bh9-kw49m3cr aa cced?    N

参考答案:     查看本题详细解析

标记此题
42#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  An organ pipe is 112 cm lojm,th6i8dd;-un p .8een (gefng. What are the fundamental and first three audible overtones if the pipe - 8medg thup6d (e8;nin e.j,fis
(a) closed at one end, $f_{1}$ =    Hz $f_{3}$ =    Hz $f_{5}$ =    Hz $f_{7}$ =    Hz
(b) open at both ends?$f_{1}$ =    Hz $f_{2}$ =    Hz $f_{3}$ =    Hz $f_{4}$ =    Hz

参考答案:     查看本题详细解析

标记此题
43#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  (a) What resonant frequency would you expect from blowing across the top lrr1e. sd),hj of an empty soda bottle that is 18 cm deep, if you assumed it was a closerlr)ds.e j1,h d tube?    Hz (b) How would that change if it was one-third full of soda?   Hz

参考答案:     查看本题详细解析

标记此题
44#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  If you were to build a pipe organ with open-tube pipes spanning the rank*7qc.pg ite;pz 8xp,ge of human hearing (20 Hz to 20 kHz), what would be the range of the leng 7 i;c,xqp ppt*.gez8kths of pipes required? $L_{20 Hz}$ =    m $L_{20 kHz}$ =    $ \times10^{ -3}$m

参考答案:     查看本题详细解析

标记此题
45#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A tight guitar string hafgd5y275kmn nlfi fi/ +srj*)s a frequency of 540 Hz as its third harmonic. What will be its fundamental frequency if ii /jn7f )n5r+2sfyfl kdgi m*5t is fingered at a length of only 60% of its original length?   Hz

参考答案:     查看本题详细解析

标记此题
46#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  An unfingered guitar string is 0.7 l3ufk b,gqr/;3 m long and is tuned to play E above middle C bql/ r;k 3ug,f(330 Hz).
(a) How far from the end of this string must the finger be placed to play A above middle C (440 Hz)?$\approx$    m
(b) What is the wavelength on the string of this 440-Hz wave? $\approx$    m
(c) What are the frequency and wavelength of the sound wave produced in air at 20°C by this fingered string?    Hz    m

参考答案:     查看本题详细解析

标记此题
47#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  (a) Determine the length of an open organ pipe t0gkrub/* pee4hat emits middle C (262 Hz) when the/40* egpeb kur temperature is 21 $^{\circ} $ C.    m
(b) What are the wavelength and frequency of the fundamental standing wave in the tube?    Hz    m
(c) What are $\lambda$ and $f$in the traveling sound wave produced in the outside air?    Hz    m

参考答案:     查看本题详细解析

标记此题
48#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  An organ is in tune athtl7-l5idpt 1sugr6 s j:z)i)e 4)nby; acj2f 20 $^{\circ} $ C. By what percent will the frequency be off at 5.0 $^{\circ} $ C?    %

参考答案:     查看本题详细解析

标记此题
49#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  How far from the mouthpiece of the flute in Example 12–10 should t4fvms d9jq6izxku*nu 4 /u6t6he hole be that must be uncove 4 z6uinq9suuf* 6v /jdkmx46tred to play D above middle C at 294 Hz?    m

参考答案:     查看本题详细解析

标记此题
50#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  (a) At T = 20 $^{\circ} $C how long must an open organ pipe be to have a fundamental frequency of 294 Hz?    m
(b) If this pipe is filled with helium, what is its fundamental frequency?   Hz

参考答案:     查看本题详细解析

标记此题
51#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A particular organ pipe can resonate at 264 Hz, 4qhizt+s 1cyv a)2l8) s6shz7h 40 Hz, and 616 Hz, but not at any other frequenc7 )+vq8i)6hsshzclz2hayts1 ies in between. (a) Show why this is an open or a closed pipe.   (b) What is the fundamental frequency of this pipe?   Hz

参考答案:     查看本题详细解析

标记此题
52#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A uniform narrow tube 1.80 m long is open at both ends. It resonxdp+7xfhu s:1 ates at two successive harmonics of frequencies 275 Hz and 330 Hz. What is p1xxh7ufs d+:
(a) the fundamental frequency,    Hz
(b) the speed of sound in the gas in the tube?$\approx$    $ \times10^{2 }$ m/s

参考答案:     查看本题详细解析

标记此题
53#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A pipe in air at 20 .2ces1/+mjlkt c psgp)u8sx;zhq 7* s$^{\circ} $ C is to be designed to produce two successive harmonics at 240 Hz and 280 Hz. How long must the pipe be, and is it open or closed?    f =    m

参考答案:     查看本题详细解析

标记此题
54#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  How many overtones are ql2 3i80xxbhut knz); present within the audible range for a 2.14-m-long organ pipe at 20 ; x)t3n khb82xq0uilz $^{\circ} $ C
(a) if it is open,   
(b) if it is closed?   

参考答案:     查看本题详细解析

标记此题
55#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The human ear canal is ap0f p6) r;tndncproximately 2.5 cm long. It is open to the outside and is closed at the other end by the eardrum. Estimate the frequencies (in the audible range) of the standing waves in the ear canal. What is the p;6 d ctnn0)frrelationship of your answer to the information in the graph of Fig. 12–6? $f_1$ =    Hz $f_3$ =    Hz $f_5$ =    Hz


参考答案:     查看本题详细解析

标记此题
56#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A piano tuner hears one beat every 2.0 s wh4jgrn6t7hmo 3w7 , 2e(en 7,ttvf qsbaen trying to adjust two strings, one of which is sounding 440 Hz. How far off in fr 6omnbwn (3gjter 7v727f ahtq4ts ,,eequency is the other string? ±    Hz

参考答案:     查看本题详细解析

标记此题
57#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  What is the beat frequency if middle lw9a9inp-/esxor i h6 h;7l9mji3 )ioC (262 Hz) and $C^#$ (277 Hz) are played together?    Hz What if each is played two octaves lower (each frequency reduced by a factor of 4)? $\approx$    Hz

参考答案:     查看本题详细解析

标记此题
58#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A certain dog whistle operatez 03fqm c a(iq,;nn0cmu)x3bhs at 23.5 kHz, while another (brand X) operates at an unknown frequency. If neither whistle can be heard by humans when played separately, but a shrill whine of frequency 5000 Hz occurfmcc( 3q q30n, mxa) hbnizu0;s when they are played simultaneously, estimate the operating frequency of brand X.    kHz

参考答案:     查看本题详细解析

标记此题
59#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A guitar string produces 4 beats/s wheqhuw5frj( )3 c1vx; g2edo-sbn sounded with a 350-Hz tuning fork and 9 beats/s when sounded with a 355-Hz tuning fork. What is the vc);or( u2vwsx5j3 q bd-e1g fhibrational frequency of the string? Explain your reasoning.    Hz

参考答案:     查看本题详细解析

标记此题
60#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Two violin strings are tuned to the same frequency, 294 H9c.)o) io:lnv2sfjwo z. The tension in one string is then decreased by 2.0%. What will be the beat f2i ).j9oof olw:snvc )requency heard when the two strings are played together? [Hint: Recall Eq. 11–13.]    Hz

参考答案:     查看本题详细解析

标记此题
61#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  How many beats will be heard if two identic62ac1j5hivdpnoc 4-y;n l d 2wal flutes each try to play middle C (262 Hz), but one is at 5.0°C and the other at 251-w5p2dcnjhvlyc i2a ;ndo6 4.0 $^{\circ} $ C?    beats/sec

参考答案:     查看本题详细解析

标记此题
62#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  You have three tuning forke v6fv 1ow;tk4s, A, B, and C. Fork B has a frequency of 441 Hz; when A and B are sounded together, a beat frequency of 3 Hz is heard. When B and C are sounded together, the beat frequency is 4 Hz. What are the possible frequencies of A and C? What beat t;1we okf4vv6 frequencies are possible when A and C are sounded together?$f_A$ =    Hz or    Hz
$f_C$ =    Hz or    Hz
|$f_A$-$f_C$|    Hz or    Hz

参考答案:     查看本题详细解析

标记此题
63#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Two loudspeakers arecdxhf yd ,:gs8eo5;: z.udhi/pc8r 3 v 1.80 m apart. A person stands 3.00 m from one speaker and 3.50 m from the sdc :uf:d i.;3cpvy88zer/hx5gh , doother.
(a) What is the lowest frequency at which destructive interference will occur at this point? f =    Hz
(b) Calculate two other frequencies that also result in destructive interference at this point (give the next two highest). Let T = 20 $^{\circ} $C $\approx$    Hz $\approx$    Hz

参考答案:     查看本题详细解析

标记此题
64#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Two piano strings are supposed to be vibrating at 132 Hz, but a pita 0tbjkq -2.uz.jhw -9u rg:h s44fvsano tuner hears three beats every 2.0 s when they are played together. (a) If one is vibrating at 132 Hz, what must be the freq4 kbh-s t.4wu:t. vsq29a fz0jguhj -ruency of the other ?   Hz    Hz
(b) By how much (in percent) must the tension be increased or decreased to bring them in tune?   % increase    %decrease

参考答案:     查看本题详细解析

标记此题
65#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A source emits sound of wavelengths 2.64 m and 2.76 m in air. H98hip 2sx bewm/1s):s lwbu u3ow many beats per second will be heard? (Assume T = biesu: plx81sh/su3wb9m 2)w 20 $^{\circ} $C)$\approx$    Hz(round to one decimal place)

参考答案:     查看本题详细解析

标记此题
66#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The predominant frequency of a certain fire engine’s siren is 1550 Hz 71z,05dz+6ozzx ml zitc mpp,when at rest. What frequency do y7 p6zzmpmzc5,liz,0 do x1+ztou detect if you move with a speed of 30 m/s
(a) toward the fire engine,    Hz
(b) away from it?   Hz

参考答案:     查看本题详细解析

标记此题
67#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  You are standing still. What8+0dv:dc0vf aw :(* kkigezyt frequency do you detect if a fire engine whose siren emits at 1550 Hz moves kd vt8y*awdfe+igv(k0:c : 0z at a speed of 32 m/s
(a) toward you,    Hz
(b) away from you?   Hz

参考答案:     查看本题详细解析

标记此题
68#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  (a) Compare the shift in frequency if a 2000-Hz source is moving towz 9839)9xd9viqix h3jh yhlgsard you at 15 m/s versus you moving lxhvh9) g iz3ys8x9d9h3iqj9 toward it at 15 m/s Are the two frequencies exactly the same? Are they close? $f'_{source\,movine}$    Hz
$f'_{observe\,movine}$    Hz
(b) Repeat the calculation for 150 m/s and then again
$f'_{source\,movine}$    $ \times10^{ 3}$Hz
$f'_{observer\,movine}$    $ \times10^{ 3}$Hz
(c) for 300 m/s What can you conclude about the asymmetry of the Doppler formulas?$f'_{source\,movine}$    $ \times10^{ 3}$Hz
$f'_{observer\,movine}$    $ \times10^{ 3}$Hz

参考答案:     查看本题详细解析

标记此题
69#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Two automobiles are equipped with the same single frequency horn. When one-gs)n 1jugqn y -o3iul;02.jnn hg nh1 is at rest and the other is moving toward the first at 15 m/s the driver at rest hears a beat frequency of 5.5 Hz. What is the frequency the horns emit? Assume T = ny 1gio;qh-jg) 12jnnhu s0l.gnnu3- 20 $^{\circ} $C    Hz

参考答案:     查看本题详细解析

标记此题
70#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A bat at rest sends out ultrasonic sound waves at 50.0 kHz and receives them r6/pls -ym91ks upta *neturned from an object moving directly away from it at 25 m/s What is the received sound frequm l uy96ansp-t/1 ksp*ency?    $ \times10^{ 4}$ Hz

参考答案:     查看本题详细解析

标记此题
71#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A bat flies toward a wall at a speed of 5 m/s As it flies, the bat emits egmtvwjg j+7li0op), 9s19lwan ultrasonic sound wave withv9, wojgs0e l)g p9jtl1mi+7w frequency 30.0 kHz. What frequency does the bat hear in the reflected wave?    $ \times10^{4}$ Hz

参考答案:     查看本题详细解析

标记此题
72#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  In one of the original Doppler experiments, a tuba was played on a mqqt8licm,i;7fh (: mgoving flat train car at ag f;q ml,c8:miq hti7( frequency of 75 Hz, and a second identical tuba played the same tone while at rest in the railway station. What beat frequency was heard if the train car approached the station at a speed of 10 m/s ?   Hz

参考答案:     查看本题详细解析

标记此题
73#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A Doppler flow meter uses ultrasound waves to measure blood-flow s*4lgdc,d 0hcn 3:hil kpeeds. Suppose the device emits sound at 3.5 MHz, and the speed of sound in human tissue is taken to be 1540 m/s What is the expected beat frequency if blood is flowing in large leg ,c kd4l*gci:0h n3ldharteries at 2 cm/s directly away from the sound source?   Hz

参考答案:     查看本题详细解析

标记此题
74#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The Doppler effect using ultrqw1z5p ysv4xk1/yhy( f:nm mg /hwk2 :asonic waves of frequency $2.25 \times10^{ 6}$Hz is used to monitor the heartbeat of a fetus. A (maximum) beat frequency of 500 Hz is observed. Assuming that the speed of sound in tissue is $1.54 \times10^{3 }$ m/s calculate the maximum velocity of the surface of the beating heart.    m/s

参考答案:     查看本题详细解析

标记此题
75#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A factory whistle emits sound of frequency 570 Hz. When the wind vezm,-d7d rzw)c locity is 12 m/s from the north, what freq-wzd), 7dc rzmuency will observers hear who are located, at rest,
(a) due north,   Hz
(b) due south,   Hz
(c) due east,    Hz
(d) due west, of the whistle? What frequency is heard by a cyclist heading    Hz
(e) north    Hz
(f) west, toward the whistle at 15 m/s?   Hz
Assume T = 20 $^{\circ} $C

参考答案:     查看本题详细解析

标记此题
76#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  How fast is an object moving :v:;kb3sjma07 mqv ouon land if its speed at 20 $^{\circ} $C is Mach 0.33?    m/s
(b) A high-flying jet cruising at 3000 km/h displays a Mach number of 3.2 on a screen. What is the speed of sound at that altitude?    m/s

参考答案:     查看本题详细解析

标记此题
77#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  An airplane travels at Mach 2.3 where the spee2.kayv)0jxnikt3kk q,x.yj ;d of sound is 310 m/s (a) What is the angle the shock wave makes with the direction of the airplane’s motij3ki 0kq) xk;ax.,yyt. j2vknon?    $^{\circ} $
(b) If the plane is flying at a height of 7100 m, how long after it is directly overhead will a person on the ground hear the shock wave? $\approx$    s (Round to the nearest integer)

参考答案:     查看本题详细解析

标记此题
78#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A space probe enters the thin atmosphp,uc.2rfeiu 1ere of a planet where the speed of sound is only about 3cr ,i1.2 pfueu5 m/s
(a) What is the probe’s Mach number if its initial speed is 15000 km/h$\approx$    (Round to the nearest integer)
(b) What is the angle of the shock wave relative to the direction of motion?    $^{\circ} $

参考答案:     查看本题详细解析

标记此题
79#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A meteorite traveling 8500 m/s strikes the ocean. Determine the shock waveco4 l*j7til0,q-tt wz angle it j,iw4tt-q*0 co z7ltlproduces
(a) in the air just before entering the ocean, $\approx$    (Round to the nearest integer)
(b) in the water just after entering.    $^{\circ} $
Assume T = 20 $^{\circ} $C

参考答案:     查看本题详细解析

标记此题
80#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
Show that the angle s,dleswxx( :)6wi 7ky$/theta$ a sonic boom makes with the path of a supersonic object is given by Eq. 12–5.
参考答案:    

标记此题
81#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  You look directly overhead and see a plane exactly 1.5 km above the ground flyiv ngnx4o. 8kn-ng faster than the speed of sound. By the time you hear the sonic boom, the planxgonkv -.4n 8ne has traveled a horizontal distance of 2.0 km. See Fig. 12–34. Determine
(a) the angle of the shock cone, $\theta$    $^{\circ} $
(b) the speed of the plane (the Mach number). Assume the speed of sound is 330 m/s   


参考答案:     查看本题详细解析

标记此题
82#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A fish finder uses a sonar device thelteg. 1oxf (,at sends 20,000-Hz sound pulses downward from the bottom of the boat, and tlg ef,ot 1.e(xhen detects echoes. If the maximum depth for which it is designed to work is 200 m, what is the minimum time between pulses (in fresh water)?    s

参考答案:     查看本题详细解析

标记此题
83#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Approximately how many octavewnnp7 w(r):i ns are there in the human audible range? $\approx$    octaves (Round to the nearest integer)

参考答案:     查看本题详细解析

标记此题
84#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A science museum hasvy 2aq;;c f8qe a display called a sewer pipe symphony. It consists of many plastic pipes of various lengths, which are open on both ends.cy2q aq ;f;ve8
(a) If the pipes have lengths of 3.0 m, 2.5 m, 2.0 m, 1.5 m and 1.0 m, what frequencies will be heard by a visitor’s ear placed near the ends of the pipes?
$f_{3.0}$ =    Hz
$f_{2.5}$ =    Hz
$f_{2.0}$ =    Hz
$f_{1.5}$ $\approx$    Hz (Round to the nearest integer)
$f_{1.0}$ $\approx$    Hz (Round to the nearest integer)
(b) Why does this display work better on a noisy day than on a quiet day?

参考答案:     查看本题详细解析

标记此题
85#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A single mosquito 5.0 m from a person makes a sound clo ,8.o-vds5awpvp ov:;;cvn c me2iw)zse to the threshold of human hearing (0 dB)-i a;.v cn)5:,vpwsv o8cwd;2 zepvom. What will be the sound level of 1000 such mosquitoes?    dB

参考答案:     查看本题详细解析

标记此题
86#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  What is the resultant sound level when an 82-dB sound and an 87-dB sound o,vixra * :aoi1f 3xxi5a+uu0are heard simultaneu30ovrx a,x f5 iu+* xoi:iaa1ously?    dB

参考答案:     查看本题详细解析

标记此题
87#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The sound level 12.0 m from a loudspeaker, placed i ,qik( zxy:jv6kjfp)en 4 t7(bt0q2cin the open, is 105 dB. What is the acoustic power output (W) of the speaker, assumin4i qz jj k0(2 tvxe7ic)n f:tkq,6pby(g it radiates equally in all directions?    W

参考答案:     查看本题详细解析

标记此题
88#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A stereo amplifier is rated at 150 W output at 1000 du7wjnqs c6rnv2v)d52 ovj - *Hz. The power output drops by 10 dB at 15 kHz. What is the power output in wattscdvnq rj)n s 72vu*jo6-w5vd2 at 15 kHz?    dB

参考答案:     查看本题详细解析

标记此题
89#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Workers around jet aircraft typically wear protective devices4wjhg9 ;8 s2 -laid tt)qyxy5aau3 (yt over their ears. Assume that the sound level of a jet airplane engine, at a distance of 30 m, is 140 dB, and that the average human ear has an effective radius of 2.0 cm. What would be the power intercepted by an unprotected l(2q48y ysa3y;d gwt 5h jtaaxit)-9uear at a distance of 30 m from a jet airplane engine?    W

参考答案:     查看本题详细解析

标记此题
90#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  In audio and communications systems, the fqhh;fo( 26k )fg o/ofgain, $\beta$ in decibels is defined as
$\beta$ = 10log($\frac{P_{out}}{P_{in}}$)
where $P_{in}$ is the power input to the system and $P_{out}$ is the power output. A particular stereo amplifier puts out 100 W of power for an input of 1 mW. What is its gain in dB?   dB

参考答案:     查看本题详细解析

标记此题
91#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Each string on a violin arws.u/x*i-5d- w diw is tuned to a frequency 1$\frac{1}{2}$ times that of its neighbor. The four equal-length strings are to be placed under the same tension; what must be the mass per unit length of each string relative to that of the lowest string?
$f_{A}$ =    $\mu_{A}$
$f_{B}$ =    $\mu_{A}$
$f_{C}$ =    $\mu_{A}$

参考答案:     查看本题详细解析

标记此题
92#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The A string of a violin is 32 cm long between fixed o tpf/m:c a*k+4ow v6k b.;utrpoints with a fundamental frequency of 440 Hz and a mass per unit l vct*/tp.:a4mwukrfko+6 b ;o ength of $6.1 \times10^{-4 }$ kg/m
(a) What are the wave speed and tension in the string?    $ \times10^{2 }$ m/s    N
(b) What is the length of the tube of a simple wind instrument (say, an organ pipe) closed at one end whose fundamental is also 440 Hz if the speed of sound is in air?    m
(c) What is the frequency of the first overtone of each instrument?   Hz    Hz

参考答案:     查看本题详细解析

标记此题
93#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A tuning fork is set into vibration above a vertical open tube find)+chd .z4hcv-n ; rqlled with water (Fig. 12–35). Tn;hr nczd+d4) v.- cqhhe water level is allowed to drop slowly. As it does so, the air in the tube above the water level is heard to resonate with the tuning fork when the distance from the tube opening to the water level is 0.125 m and again at 0.395 m. What is the frequency of the tuning fork?   Hz


参考答案:     查看本题详细解析

标记此题
94#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A 75-cm-long guitar string of mass 2.10 g is near a tube that e01 bnmkvhl 2-8e5c6- t dambris open at one end and also 75 cm long. How much tension should be in the string if it is to produce resonance (idect- 5r 0mh e2b6vb1-mka8lnn its fundamental mode) with the third harmonic in the tube?    $ \times10^{ 2}$ N

参考答案:     查看本题详细解析

标记此题
95#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
A highway overpass was observed to resonate as one fulxw98w +idhv k*9 xw /pm:i3rzul loop ($\frac{1}{2}\lambda$) when a small earthquake shook the ground vertically at 4.0 Hz. The highway department put a support at the center of the overpass, anchoring it to the ground as shown in Fig. 12–36. What resonant frequency would you now expect for the overpass? Earthquakes rarely do significant shaking above 5 or 6 Hz. Did the modifications do any good?
参考答案:    

标记此题
96#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A person hears a purei*yu8 - o +eu4vq1myjo tone in the 500–1000-Hz range coming from two sources. The sound is loudest at points equidistant from the two sources. To determine exactly what the frequency is, the persiyo1yq 8jv-+ umou 4*eon moves about and finds that the sound level is minimal at a point 0.34 m farther from one source than the other. What is the frequency of the sound?   Hz

参考答案:     查看本题详细解析

标记此题
97#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Two trains emit 424-Hz whistles.q5a0raun ;j77)pk z ub One train is stationary. The conductor on the stationary train hears a 3.0-Hz beabja )7n0r7uzk ap;5uq t frequency when the other train approaches. What is the speed of the moving train?   m/s

参考答案:     查看本题详细解析

标记此题
98#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The frequency of a steam train whistle as it approaches you is j0w zovd*wrq 7 dg4h;,538 Hz. After it passes you, its frequenjg7 dz ,doqwr4 ;vh0w*cy is measured as 486 Hz. How fast was the train moving (assume constant velocity)?    m/s

参考答案:     查看本题详细解析

标记此题
99#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  At a race track, you can e:s(wroxej -o-qek)5u stimate the speed of cars just by listening to the difference in pitch of the engine noise between approaching and receding cars. Suppose the sound swox5r: k( oej)-u-qeof a certain car drops by a full octave (frequency halved) as it goes by on the straightaway. How fast is it going?    m/s

参考答案:     查看本题详细解析

标记此题
100#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Two open organ pipes, sounding together,k fjefom:-2i) mkot2m4;: mcv9pu y i, produce a beat frequency of 11 Hz. The shorter one ,oom:tup4v;-c mky29 fi2e:mj mif)k is 2.40 m long. How long is the other?    m

参考答案:     查看本题详细解析

标记此题
101#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
Two loudspeakers are at opposite ends of a railroad car as ifngaa r3vi x*+8 e9x9jf u3tg(t moves past a stationary observer at 10 m/s as shown in Fig. 12–37. If the speakers have identical sound frequencies of 213xjx3(i8 9* +nfet9r avgfg ua2 Hz, what is the beat frequency heard by the observer when (a) he listens from the position A, in front of the car, (b) he is between the speakers, at B, and (c) he hears the speakers after they have passed him, at C?
参考答案:    

标记此题
102#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  If the velocity of blood flow in the aorta is normally about 0.32 m/s what beat k2zl)/-0fymc e.2zb: 1j b5 kz w7+brhehksos frequency would you expect if 5.50-MHz u.2lhs1) 2z +sbe5b7k-k/ o j0ky :wbczfmzeh rltrasound waves were directed along the flow and reflected from the red blood cells? Assume that the waves travel with a speed of $1.54 \times10^{3 }$ m/s   $ \times10^{3 }$Hz

参考答案:     查看本题详细解析

标记此题
103#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A bat flies toward a moth fx,4 mvew7hjud j5 ;w;at speed 6.5 m/s while the moth is flying toward the bat at speed 5 m/s The bat emits a sound wave of 51.35 kHz. What is the frequency of the wave detected by the bat after that wave reflects off the mothxh4v; 7;jeuf5jww m d,?    kHz

参考答案:     查看本题详细解析

标记此题
104#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A bat emits a series of high frrwj y2q26p 5yr 4(jztvntn, ;qequency sound pulses as it approaches a moth. The pulses are approximately 70.0 ms apart, and each is about 3.0 ms long. How far away can the moth be detected by the bat so that the echo from one chirp returns before the next chirp is emitted? rjyz , ttjpvq5yr2 wq4(n62;n   m

参考答案:     查看本题详细解析

标记此题
105#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
The “alpenhorn” (Fig. 12–38) was once 6u0 2j dnxc+.u*g/zu vo6aheeused to send signals from one Alpine village to another. Since lower frequency sounds are less susceptible to intensity loss, long horns were used to create deep sounds. When played as a musical instrument, the alpenhorn must be blown in such a way that only one of the overtones is resonatin/*2g6vz6+ o 0h.dn uuue cexajg. The most popular alpenhorn is about 3.4 m long, and it is called the F sharp (or G flat) horn. What is the fundamental frequency of this horn, and which overtone is close to F sharp? (See Table 12–3.) Model as an open tube.
参考答案:    

标记此题
106#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Room acoustics for stereo h4vyllz aw8 w 4cgwc;dq 46-xw8ulre/d17 jh9listening can be compromised by the presence of standing waves, which can cause acoustic “dead spots” at the locations of the pywq8cwc68rhl daz ew94hl; ld7/x14v juw4- gressure nodes. Consider a living room 5.0 m long, 4.0 m wide, and 2.8 m high. Calculate the fundamental frequencies for the standing waves in this room.
Length : f =   Hz
Width : f =   Hz
Height : f =   Hz

参考答案:     查看本题详细解析

标记此题
107#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A dramatic demonstration, called “singing rods,” involves a long, slender aluminpdpj 5h 4prmqi nx*k3.4),ni+ny,bq mum rod held in the hand near the rod’s midpoint. The rod is stroked with the other hand. With a little practice, the rod can be made to “sing,” or emnkb*+p rmi, p , x5 yihnmq4q3j4n.p)dit a clear, loud, ringing sound. For a 90-cm-long rod,
(a) what is the fundamental frequency of the sound?    $ \times10^{ 3}$ Hz
(b) What is its wavelength in the rod,    m
(c) what is the traveling wavelength in air at 20 $^{\circ} $ C?    m

参考答案:     查看本题详细解析

标记此题
108#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The intensity at the threshold of hearing for the human ear at a frf xx:bk a uq0c4z3ly2s4ox.*nequency of about 10sc x4:l3uzq4* aon.2kfyxb0 x00 Hz is $I_0$ = $1 \times10^{12 } W / m^2$ for which $\beta$ the sound level, is 0 dB. The threshold of pain at the same frequency is about 120 dB, or $I$ = $1 W / m^2$ corresponding to an increase of intensity by a factor of $10^{12}$ By what factor does the displacement amplitude, A, vary? 10$^{a}$ a =   

参考答案:     查看本题详细解析

标记此题
109#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A plane is traveling at Mach 2.0. An observer on the ground hears the sonic boomk3po qk*pr78ci h+br9 1.5 min after the plane passes directly overhhpki9b8k7+oq3 cp rr *ead. What is the plane’s altitude?    $ \times10^{4 }$ m

参考答案:     查看本题详细解析

标记此题
110#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The wake of a speedboat is h-27t0jmzw 5qt lrqft*9vz6 f15 $^{\circ} $ in a lake where the speed of the water wave is 2.2 km/h What is the speed of the boat?    km/h

参考答案:     查看本题详细解析

总分:110分 及格:66分 时间:不限时
未答题: 已答题:0 答错题:
当前第 题,此次习题练习共有 110 道题
本平台(https://tiku.one/)支持练习,作业与考试(自动评分)三种模式,群组成绩统计排序导出,题目动态变量实现同卷千人千题
如果您对本系统感兴趣,想加入我们或者想进行任何形式的合作,请加微信 skysky1258

浏览记录|手机版首页|使用帮助|题库网 (https://tiku.one)

GMT+8, 2025-10-3 10:10 , Processed in 0.777401 second(s), 242 queries , Redis On.