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: 匿名未登录  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 trav ;wer r-ikh;w4els as a wave?
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 soun+bwx el; -4ztumy:l1 zd 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 playm 7 x7cmrg8nzsds65s +9 am6ml with a homemade “telephone” by attaching a string to the bottoms of two paper cups. When the string is stretched and a child speaks into one m65sx gscz68mmms7r7n9 +a d lcup, 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 a0m9iuj b b1vm,. )ssefrom air into water, do you expect the frequency or wavelength to )b9imv0 b1mas .u j,sechange?
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 signifym :s-8u;aoz)x j(uuqy ue(86asth(c iu 6u -y(y( o)auhjau8;8ess:m( xcqtzcantly 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-pifpa-fr n2 .an5tched. Why?
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 in a room qrjd5w tfsx(b x*qt1(bt5 +j(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 reduce the amhd7 md3x. sm6jplitude of sounds in various frequency ranges. (An example is a car muffl. hdd3msm6 j7xer.)
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–. xjvl7t+c.n u nmztu:90)tx0 f*dyot30) spaced closer together as you move up th9mnolj .7v0d x u.tct:0 tfn+zytu )x*e fingerboard toward the 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 behinwnk o1 :l3pxdjqw )6e2d a building. 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 the high-frequency noise. Explain. [Hintwxk6n:32 1l )wqdeojp : 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 “ r*2jhrwaco :umf568yhwv+/r interference in space,” whereas beats can be said to be dujw5 r:ar/u6+o*hm hw 8rvf 2cye 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 tjv c7/j9u-4 nev,py dche speakers were lowered, would the points D and C (where destructive and constructivyvd,-vj9j/ p 7cncue4e 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 protczo0,,l4l4sw +z0udy hd dl0tecting 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 zl s4dd htld+w,0o0czy4u,l0that 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 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 j-krci n+2vpg-hxi5fbe9 9s7 can be thought of as a superposition of two sound waves with slightly different frequkn j9ix79hiv5fr -bs g-c2e+ pencies, 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 source and observer move inr,buquc wkm/ fn+aj1mlj fi3/i 3l 0+1 the same direction, wit03 jqlmbl1ru/fi+m kn+1ajiuw f3c /,h the same velocity? Explain.
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 7:/ iiav4 4;vcpbl:klstd;ay a person at:a4b /a4p;ysilcdvl : vkt 7i; rest with respect to the source? Is the wavelength or velocity changed?
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 monito tfk8lvuq6c zsfux2+v .3;7usr 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 sound of the whistle? Explain your r.s fv+763vt lsxcfuuq;2 8uzkeasoning.

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 echos7kcqu s mv86q9pe(49ew,i vj of her shout reflected by a cliff at the far qs v4w i,cqe(sm6vj7ue 8pk99end 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 hears themq(eh n: 1r.yz echo of the sound reflected from the ocean floor directly below 2.5 s later. Howyh1nr(ze:.m q 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 i8uh ks t-3)3 8apqmugen air at 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 just above a school of tuna on a foggy day.2to3w+ xynj 7h x9(gsa Without warning, an engine backfire occurs on another bog3(sxtnhjxyo7 29 +awat 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 t qnxni0gx 2-pt0su f57op of a cliff. The splash it makes when striking the waun2q7 5-p fi0gx0txsn ter below is heard 3.5 s later. How high is the cliff?    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 huge stone strij;kls1oce8 5m,xu0 cn ke the concrete pavement. A moment later two kse;xc ,no5l108ju c msounds are heard from the impact: one travels in 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 m a x)2za.xw(mnc b,; -w6ryemover one mile of distance by the “5-second rule” for estimating the distance from a lightning strike if thcwxe.m2zrmna w ;b )m,6-ax(ye temperature is (a) 30 $^{\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 sound at the pain/,tdx7b; qc jz 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 xmdqnk+ 6/ 8 x0;7rl0jdcko+vc/tuaz of a sound whose 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 produce a sound level of 9dn+cqvb -fc63os 9 p5f5 dB when fired simultaneously at a certain place, what will be the sound level if only one is exploded? [Hint: Add intensities, not dB’sfs -nb6dc 3+5f9 qvpoc.]    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 four k yb0r4 ntye9ji+; 5wpequally noisy jet enrk5 490t;yw y nejbpi+gines 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’s.]    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 hav -206 g+zrb h.dy*piizu uiq2le a signal-to-noise ratio of 58 dB, whereas for a CD player it is 95 dB. What is the ratio iguzlpz2. u+irq b02*-yhd 6iof 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 from a person speakingr1ft5pmptl0 u8q +;ot in normal conversation. Use Table 12–2. Assume the sound spreads roughly uniformly over a sphere cente8r0q mutl 1ttp;f o5p+red on the 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 eardrum whose a8y+g( n6dyoi 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, while the moreda09cf8 7zye/gl tjfuu7h3ld 7h ( q(q modest amplifier B is rated at 40 W. (a) Estimate the sound level inj fq3(thuyd8c7 79eza0l (uqgdh f7l / decibels you would expect at a point 3.5 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 mnhk te6*.t3y-3v8r cnhs t9 qheter registered 130 dB when placed 2.8 m in front of a loudspe*.tcr-stv3e968y3hk t n hh nqaker 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 typically deb*cb2aw; :iy etect a difference in sound level of 2.0 dB. What is the ratio of tb;a*cbywe:2 ihe amplitudes of two sounds whose levels 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 will tmsguu)o i8f kb06tw 5-he intensity increase? Increase by a factor o )5uwb0-8k tsf 6omuigf    (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 amplitudes, but /yq *z3lt,g/ wqsw3-ypy k3)mzhwff 0 one has twice the frequency of the other. What is the k)03wqz,wptq zf 3mflyg/y- hw*/s3y ratio of their intensities?   

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 li6g)-ui9o1 r-a2f3j3 *5yqzwzq z ps vtyyp(vevel (in dB) of a sound wave in air that corresponds to a displacementsqtzgj * y-rz)3-(pf6u w359y va io1i2ypzq v 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 h7al ;qv ix)/7-hgxv ouave what sound level to seem as loud as a 100-Hz tone that has a 50-dB sound ix)/vlvh7u- xog ;qa7 level? (See Fig. 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 tf ;phn*gpn;8 0m9lmbehat an ear can detect when the sound level is 30 dB? (See Fig. 12–h ;bg pm0fn;mp8e9ln*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 sound levels. What is the+ut: wnuqb/a.dv* c21;apd wm ratio of highest to lo2p *1u .; qt macnwudbd/awv+:west intensity 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 fundamenwsc28j i0yw 4dtal frequency of 440 Hz. The length of the vibrating portion is 32 cm, and it ha28s w4idjw y0cs a mass of 0.35 g. Under what tension must the string be placed?    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 long. What are tr.o o)nb17z yrhe fundamental and first three audible overtones if t)z rrbn71 ooy.he pipe is
(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 wpve cxie-x22 ,ould you expect from blowing across the top of an empty soda bottle that is 18 cm deep, if you assumed it was a closed tube 2xcxe2, p-iev?    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 pipes74x vz.:f5hzui p1g xe spanning the range of human hearing (20 Hz to 20 kHz), what would be the range of the lengths of pipes required? uhx:5zf7i zevgx p4.1$L_{20 Hz}$ =    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 has a frequency of 540 Hz as its third harmonic. What willq +-ce)av:m 7or.4 wmi1iyb yk be its fundamental frequency if it is fingered at a length of only 60% o+7qy4c )e:k -b iwoair1m.ymvf 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 so,y-dmh6r 31jesh 2 obtring is 0.73 m long and is tuned to play E above middle C (330 Hz). ,em rsh1bh6 o-j3 do2y
(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 s,ifo1i8 u c/6nrdrcyml c07 4organ pipe that emits middle C (262 Hz) when theo,0scm 4/frycl1iu c drn7i8 6 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 at 2 yr;y oqa,1k+jwq;jq10 $^{\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 the hole be th tjdgw/b9x,jh:l51 k/(tcsw u(t hl4 natl:1wdsjlthc 4,gh9b 5/ /t (ujxnk(tw must be uncovered 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, 440 Hn9: +3: b+tqs7ykd0 ilk yo-ty.vns uafadp2 /z, and 616 Hz, but not at any other frequencies in between. (a) Show why -d:n n3yfvt7bys9o+2a:lt+ qsk dp 0a.kiyu/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 zsmxh4 7s9cfk/(j b e(km qom/nn5/0c1.80 m long is open at both ends. It resonates at two successive harmonics of frequencies 275 Hz abmx7mskohezs/5cm( 0(j/n/ 9 k 4qfcnnd 330 Hz. What is
(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 : 5e o9,seiffq$^{\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 a sn:i6y. /kovsre present within the audible range for a 2.14-m-long organ pipe at 2ino6syk /v.:s 0 $^{\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 approximately 2.5 cm long. It is open to the outside andfn21bz5*sps i is closed at the other end by the eardrum. Estimate the frequencies (in the audible range) of the standing waves21spifs* bn 5z in the ear canal. What is the relationship 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 6uaav g1drm.;w a0cj6beat every 2.0 s when trying to adjust two strings, one of which is sounding 440 Hz. How vda 6arj60gm .aw;cu1far off in frequency 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 C (26*ajz-4m.0+mr7 xhs1 9zwf h6 hbccz vm2 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 operates at 23.5 ksr 0shgy5 xd) 23qp2fsHz, 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 occurs when they are played simultaneously, gsrdyf0x2s2h35q) psestimate 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 when sounded with af cp s.;x(nk9c 350-Hz tuning fork and 9 beats/s when sounded with a 355-Hz tuning fork. What is the vibrational frequency of the string? Explain your reasoning 9s( fn;kx.cpc.    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 tu-p bq49 :wqgxjned to the same frequency, 294 Hz. The tension in one string is then decreased by 2.0%. What will be the beat frequency :-j9gq px qw4bheard 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 identical flutes each try to play middl 9mx0j9n2 2qitpo.jabe C (262 Hz), but one is at 5.0°C and the other a 2jp9 j09nt a2bmqx.oit 25.0 $^{\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 forks, A, B, a x kh1ki1ay60ynd 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 aiax y61kh 1k0ynd C? What beat 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 are 1.80 m apart. A person stands 3.00 m from one spea-lf65z8 g w9ddzstr3jf b1if*ker and 3.50 m from the other. -1gd 365f fz i*bwrz ljfd89ts
(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 ba5s)hov )ljc:jxd b3ohth72. gtcy 7 8e vibrating at 132 Hz, but a piano tuner hears three beats every 2.0 s when they are played together. (a) If one is vibrating at g:y).j)s 2th hxt cb dvc583 7lojh7oa132 Hz, what must be the frequency 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. How many be(d ip4o2/jb,wwsv2 jgats per second will be heard? (Assume T i2,vwjsd2gp/wboj 4( = 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 cert y so-,s:8facvain fire engine’s siren is 1550 Hz when at rest. What frequency do you detect,v8 s:y-oa fsc 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. What frequency do you detect if a fire e2acdaxx hf+a :cv /nj-;:8vvcngine whose siren emits at 1550 Hz mo8 vvc:a-vca+dxxa: hc;2n j/fves 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 toward you3mls 3 tcdp5f5x9h+ ho at 15 m/s ver3xosf h3mh+95 pdlt c5sus you moving 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 siqftn;75hs,)merk d6 wpq *+tgngle frequency horn. When one 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? kts )r ,7h*tfdm;n 5p+6eqgwqAssume T = 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 kHj:( ww-mg;in-8pfbe f z and receives them returned from an object moving dire-ne i: pmfwbj fg-;8(wctly away from it at 25 m/s What is the received sound frequency?    $ \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 5sw.-c 5;z nqff m/s As it flies, the bat emits an ultrasonic sw sfq5-n.fcz ;ound wave with 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 jsc n*jef80hpc8jgq2o8 k )kubaz333Doppler experiments, a tuba was played on a moving flat train car at a frequency of 75 Hz, and a second identical tuba played the same tone while at rest in the railway station.8qeb8*fpj3uks)cg hjc8 ja3 kn02oz3 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 ultrasoundp f5ihd/ ,(qn b25xyxz waves to measure blood-flow speeds. Suppose the device h2b/ i5,x5dzqy(nfxp 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 arteries 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 usingdbl * l q,a0;wrymm03r ultrasonic 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 freque4 vq*1mrbkulc1-lr tyux48 0pncy 570 Hz. When the wind velocity is 12 m/s from the north, what frequency will obse1ckb - 1 u4 0lltrm8*uqxp4vyrrvers 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 3;k t8beyzqr 4-yntl-ln,c8 kmoving on 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 speed of sound is 310 m/s (a)kywzc5 o *mc/u z6klm. dy22 m)2l.btg What is the angle the shock wave makes umbd/z yw2*c.2l6 o) cmkg2ym 5l.tk zwith the direction of the airplane’s motion?    $^{\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 atmosphere of a planet where the speed of sou nrr/en(o*/,cbgmck + nd is only about 35 m/s kcob*(//r ,g+nnmcer
(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 t;kzkjb4/m9: 4t/z-h gavnacmhe shock wave angle it produces94 anz v kka/4m:gcm ;tzj-h/b
(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 u* 3z2 j.:vm4l9bu/cla o wtao$/theta$ 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 + (hu fp5m6 rv*qay/6niw4 zrhexactly 1.5 km above the ground flying faster than the speed of sound. By the time you hear the sonic boom, the plane has traveled a horizontal distance of 2.0 km. See Fig. 12–34.yw6zi6p*a hm+n r(54/ vfquh r 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 that sends 206 /io i li55wdcppsc70,000-Hz sound pulses downward from the boti os506pc icpil57d /wtom of the boat, and then 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 octaves are there in the humugtjpeh *3 c:d:ejlj :8rw45wan 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 has a display callem q sp8dkf5i0wqu (:t:d a sewer pipe symphony. It consists of many plastic pipes of various length:0qkifs 5pqw :8(dt mus, which are open on both ends.
(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 close to the threshod7 /-lb e)osznb:- zruld of human hearing (0 dB). What will be the sound level of 1000 such mosquitoes? bl7n-r ozeduzb)-/ :s   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 8px0vaz d9(1c1pzftb 57-dB sound are heard simultaneouslyac f(zx0p9pb 1ztd51 v?    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 in the open, is 105 dffkqxrdn8l(3j db-x6p85 3zaB. What is the acoustic power output (W) of the speaker, fl rfd-kx6jb3 5dp(n3 a8xqz8assuming 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 xp9klaki1jdr( oy)7/xrn 3 n1at 1000 Hz. The power output drops by 10 dB at l173 pin)jrx(n9 drk1y /aoxk15 kHz. What is the power output in watts 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 devici .;j9f6uusdo es over their ears. Assume that the sound lid6s. ;ojuuf9 evel 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 ear 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 gain, dbg ,-p f8sq84e rt4kg$\beta$ 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 violi1,9x( w d. os*/(5lapryqki+ro jjsqcn 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 points wiby et::(ex0sen(3s6h* /sfsvig:gnr th a fundamental frequency of 440 Hz and ain6es(tbsxfvsy :h gn(3se :e0/*:rg mass per unit length 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 vertii/gtpj.evvi e;n.k6.; yr0s ecal open tube filled with water (Fig. 12–35). The 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 di0es vt. e. ie;ri/p.v;yg nkj6stance 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 ax r uyl4ya/6,u tube that is open at one end and also 75 cm long. How much tension shorl/yy, uau x64uld be in the string if it is to produce resonance (in 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 f pd4 *fgq/4tvo z2xr-4ksb q6iull 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 pure tone in the 500–1000vh(k(qb4fu y5 -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 person moves about and finds that the sound level is minimal at a point 0.34 m farther from one source5fbh 4u(k (qyv 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. One trgfe3:nbm j 5pu q34l)l :8ogjxain is stationary. The conductor on the stationary train hears a 3.0-Hz beat frequency when the other train approaches. What is the speed of the moving train:4f :u3l )3j5lgpnmj oqb gx8e  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 appfdx ;0lco7 br6roaches you is 538 Hz. After it passes you, its frequency c06 f7xrdlob ;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 qyo vah mky;(qa h6nyp d+o+ dg*)/0u:estimate the speed of cars just by listening to the difference in/v dkh n;q0(yu+h:odyy )a 6pq*+goma pitch of the engine noise between approaching and receding cars. Suppose the sound of 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, produce a beat frequency of 11 Hzr bt9pgqznbh pk3b:3t ,c).e6. The shorter one is 2.40 m long.9ek t znr3qcbt)3,b p.hpgb:6 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 it moves pastz ;dpprm7hiaf6k732g a stationary observer at 10 m/s as shown in Fig. 12–37. If the sp6;aip2 g7p7f3 dzrmkh eakers have identical sound frequencies of 212 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 aortaiith /ihzt+g xu m(xy/rtke 40z8x ,36 is normally about 0.32 m/s what beat frequency would you expect if 5.50-MHz ultrasound waves were directed along the flow and reflected from the red blood cells? Ass+/mx(ghr /i 06x ut zt 48txzyeiihk3,ume 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 at speed 6.5 m/s while the moth ilg/)c3et3 z6 v6zemgis 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 wazc6m33g egz/v6t) eilve reflects off the moth?    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 frequency sound + b 5if .sz2y1sdscumn1hb;w8s. irh,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 d.shzbus1mfi.s;c 2y r ih +5wb n81s,the echo from one chirp returns before the next chirp is emitted?    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 used tovsod(n+ 9;l wj+ xqbt.qxe*n * 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 j9 sn; + e qvqw.d(o+nx*xtbl*blown in such a way that only one of the overtones is resonating. 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 listening can be compre+v0 9p*:cdmx j7dnw;e hc /dpomised by the presence of standing waves, e:+phd0j;x v 7d*c /pn mcedw9which can cause acoustic “dead spots” at the locations of the pressure 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 6brfvw-g*/vrw/i .fh long, slender aluminum rod held in the hand near the rod’s midpoint. The rod is stroked with the other hand. With a little practice hvrf.irw -v6/w*/gfb, the rod can be made to “sing,” or emit 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 hnvvs v+ .eq/f,n1n* wekv dt2:uman ear at a frequency of abov/:sw *+v nnevd.e, qtfv2k 1nut 1000 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. h7s;qcrq2m2 hu-g c,i An observer on the ground hears the sonic boom 1.5 min after the plane passes directly overheadc2girmq uh -;c7 2qsh,. 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 15lj7l2 s .bq8bhj (a0k5dw ,meh $^{\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
    本系统支持习题练习,作业与考试三大模式,作业考试自动评分,成绩排序一键导出,可设定动态变量同一试卷千人千题
    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, 2025-7-16 04:56 , Processed in 0.278902 second(s), 241 queries , Redis On.