Sprott Contains a demonstration (in Part 7) of beat frequencies. Video Encyclopedia 10 #18 Tuning Fork Beats #19 Beats with Speaker and Oscilloscope

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1 92 Chapter 6 Sud ad Music Sprtt Ctais a demstrati (i Part 7) beat requecies. Vide Ecyclpedia 0 #8 uig Frk Beats #9 Beats with Speaker ad Oscillscpe 6-9 DOPPLER EFFEC Gals Describe the Dppler eect. (Prblem Slig) Pride the rmulas r the Dppler eect ad wrk a example. Ctet Whe a surce sud ad/r the receier me relatie t each ther, there is a shit i the requecy betwee the sud emitted ad the sud receied. his shit is idepedet the distace betwee the receier ad emitter. eachig ips his secti ca als be skipped withut resultig i prblems later i the text. We like t cer it because it's u. We begi this secti by twirlig a buzzer abe ur head i a circular ashi t let the studets experiece the Dppler eect. he studets ca clearly hear the shits i requecy. he ilm lp Dppler Eect ca be used eectiely t explai hw this happes. Ather ppular demstrati requires that yu take yur class utside. Use a audi scillatr t play the same requecy, say 000 Hz, tw speakers acig each ther ad separated by 0 m. Whe the studets me rm e speaker t the ther, they'll hear beats because the sud rm e speaker is shited up i requecy ad the ther is shited dw. he studets ca check that the eect depeds speed by ticig the chage i beat requecy with the speed they me. We hae recrded a car's hr rm the side the rad while the car passed by. By cmparig the requecies the tape with the tes a pia, we were able t calculate the speed the car t withi 5%. Flawed Reasig he Dppler eect des t deped the distace betwee the surce ad the bserer. Prblem Slig 6.6 We state Dppler rmulas r a mig surce ad a mig bserer ad cmbie them it a sigle relatiship. We the illustrate their use with a simple calculati. Film Lp Dppler Eect Vide Ecyclpedia 0 #2 Dppler Eect 6-0 SHOCK WAVES Gals Shw what happes whe a surce mes aster tha the speed the waes i the medium. Crrect a cmm misuderstadig abut sic bms. Ctet Whe a surce sud mes aster tha the speed sud i air, a abrupt pressure barrier is created. he agle the ce r this sic bm is related t the relatie speeds the surce ad the sud. he sic bm that yu hear rm supersic airplaes is t caused whe the plae accelerates past the speed sud but rather whe the pressure ce crsses yur lcati. eachig ips his secti ca be skipped. We treat this as a readig assigmet althugh mre culd be

2 Chapter 6 Sud ad Music 93 made it as ur studets seem t like eirmetal applicatis. Film Lp Shck Waes builds Dppler Shit ad ca be used r bth sectis. Cmputer Aimatis Actie Figure Aimatis are aailable the Multimedia Maager Istructr s Resurce CD. hey are rgaized by textbk chapter, ad each aimati cmes withi a shell that prides irmati hw t use the aimati, explrati actiities, ad a shrt quiz. Aswers t the Cceptual Questis. Sud exhibits the typical wae behair itererece ad tw suds will pass thrugh each ther. 2. I yu displace air mlecules rm equilibrium the restrig rce is always i the ppsite directi t the displacemet (t traserse t the displacemet), which cat prduce a traserse pulse. 3. Oly the temperature the air has a eect the speed. 4. Bth waes trael at the same speed. 5. he speed sud is aster i water. 6. Because the speed sud is aster i helium, the requecy the sud is raised. 7. he speed light is much aster tha the speed sud ad, therere, the light arries irst. 8. Because the time r the sud t arrie is ery shrt, the lightig must hae struck earby ad the sud is therere ery lud. 9. Sud waes all waelegths (r requecies) hae the same speed. 0. Sud traels aster a ht day, s yu wuld hear yur ech retur ser.. he ear plugs reduce the itesity t e-hudreth as much. 2. he decibel scale is t liear. A icrease 0 decibels represets a teld icrease i the sud eergy. his is t a 20% icrease but rather a 000% icrease. 3. Yes, requecy (which determies pitch) ad amplitude (which determies ludess) are idepedet prperties a sud wae. 4. he ludess we hear depeds the amplitude the sud wae. 5. he pitch a sud is determied primarily by its requecy. 6. Irasud has the lger waelegth. 7. I the buzzer prduces 500 pulses each secd, yur ear must receie 500 each secd because the pulses cat be created r destryed as they trael t yur ear. 8. N. Because the speed all sud waes i air is determied by the air temperature ale, ay chage i the requecy must result i a chage i the waelegth. 9. Because each ctae represets a dublig the requecy, tw ctaes represet a icrease ur times the rigial requecy r 400 Hz. 20. he secd harmic is e ctae higher tha the udametal. 2. Yu ca icrease the speed the waes a guitar strig by icreasig the tesi i the strig r decreasig its mass per uit legth. 22. Yu ca raise the requecy a guitar strig by icreasig the tesi, placig yur iger lwer dw the ret bard, r replacig a strig with e with less mass per uit legth. 23. he waelegth the udametal is twice the legth the strig. 24. he shrter waelegth will hae the higher requecy because the prduct the waelegth ad requecy must equal the speed the waes. 25. Yu wuld place yur iger e quarter the distace rm either ed the strig. he urth harmic has des at these lcatis, s it wuld t be damped ut. 26. Yu wuld place yur iger e sixth the distace rm either ed the strig r at its middle.

3 94 Chapter 6 Sud ad Music Placig yur iger at the middle the strig will t damp ut the ee harmics, while the ther lcatis will damp ut mst them. 27. Pluckig a strig harder aects the ctributis higher harmics but has eect the udametal requecy. 28. Chagig the tesi i a strig aects the speed the wae but has eect the udametal waelegth. 29. All harmics hae the same speed. 30. Yu ca chage the wae speed a guitar strig but yu cat chage the speed sud i a lute. 3. here must be des at the eds the strig because there is memet there. 32. here is a de at the clsed ed ad a atide at the pe ed. 33. he waelegth is tw times the legth the pipe. 34. he waelegth is ur times the legth the pipe. 35. he waelegth dubles. 36. Because the waelegth dubles, the requecy must cut i hal. 37. he patter represets all multiples a udametal requecy 50 hertz, which meas the pipe is pe at bth eds. 38. he patter represets ly the dd multiples a udametal requecy 00 hertz, which meas the pipe is pe at e ed ad clsed at the ther. 39. he temperature drp decreases the speed sud ad therere decreases the udametal requecy. (he waelegth stays the same because it is determied by the legth the rga pipe.) 40. Because the waelegth depeds the legth the tube, it des t chage. Because the speed the wae icreases while the udametal waelegth stays cstat, the requecy must icrease. 4. equal t 42. he udametal waelegth is twice the legth the rd. 43. he richess the sud prduced by a acustic pia results t just rm the udametal requecies but als rm the uique bled the higher harmics. his is diicult t reprduce electrically. 44. Ee whe playig the same te, the be ad the pia prduce harmics with dieret itesities. 45. Because the beat requecy depeds the dierece i the tw requecies, the beat requecy icreases. 46. Because the beat requecy depeds the dierece i the tw requecies, the beat requecy decreases. 47. Yu kw that yu are by 2 hertz but yu cat tell whether yu are t high r t lw. he beat requecy depeds the abslute alue the dierece. 48. he beat requecy is determied by the dierece betwee the tw surce requecies. he dierece is greater r the pair at 345 ad 348 hertz. 49. he beat requecy will icrease. 50. Lwerig the requecy e the tuig rks icreases the dierece betwee them. Yu must hae put the putty the lwer requecy tuig rk. 5. he requecy the whistle decreases as the trai passes yu. 52. Yu will hear a lwer requecy because the waes are spread ut by the mti the tuig rk away rm yu. 53. he speed a wae is uaected by the mti the surce. 54. Yu hear a higher requecy tha the drier hears. 55. he size the Dppler shit is decreasig s the requecy is decreasig tward its rest alue. Because the car is gettig clser, the sud is gettig luder. 56. he highest requecy will be heard whe the surce is mig astest tward the bserer. his

4 Chapter 6 Sud ad Music 95 ccurs at pit C ee thugh the sud is ludest whe the surce is at pit B. 57. Whe Elaie mes away, the requecy her buzzer is Dppler shited dw. Because the beat requecy is icreasig the tw requecies must be gettig arther apart. herere, Elaie s buzzer must hae the lwer requecy. 58. he requecy des t chage because there is mti yur ear relatie t the sire. 59. Much like a explsi the sic shck wae prduces a sharp rise i pressure as it passes the bserer. 60. he speed the bat is greater tha the speed the water waes. 6. Yu will iitially hear thig util the shck wae arries. Yu will the hear the characteristic bm llwed by egie ise. 62. he speed sud waes is lwer at greater altitude where the temperature is lwer. he pilt just has t ly higher. Aswers t the Exercises s 262 Hz s 200 Hz 343 m s m 048 Hz 343 m s 4 m 3Hz 343 m s 343 Hz m m s Hz 343 m s 7.2 m 20 Hz 3.08 m 343 m s m.72 cm 20,000 Hz 9 s 343 m s 3.09 km r 9 s.8 miles 5s 9. d t ( )( ) ( ) mile 0. d 40,000 km 000 m t 343 m s km d t 500 m s 0.4 s 600 m. ( ) ( ) s 32.4 h 309 m s 2. d d0 20 m 8.0 m m s 3. Each actr 0 i itesity is a reducti 0 db. herere, 3 0 db 30 db. 4. Each icrease 0 db represets a icrease i sud itesity a actr 0. herere, 2 0 db

5 96 Chapter 6 Sud ad Music yields a ampliied sud that is 00 times mre pwerul. 25 Hz 25 Hz, 250 Hz, 375 Hz, 500 Hz, ( ) 6. where 50 Hz he requecies measured crrespd t 4, 5, ad m s m 588 Hz 0.8 m 8. ( ) ( ).2 m.2 m 500 Hz 600 m s 9. 4 L 4m 343 m s 85.8 Hz; Hz; Hz; m L 2m 343 m s 72 Hz; Hz; 3 56 Hz; m m s m L 7.4 cm Hz m s m L 34.8 cm Hz 2 23., where 75 Hz he requecies measured crrespd t 5, 6, ad 7, s this is a pe pipe. 24., where 00 Hz he requecies measured crrespd t 5, 7, ad 9, s this is a clsed pipe. 25. ± 262 Hz ± 2 Hz 260 Hz r 264 Hz b Hz 2 Hz 358 Hz r 362 Hz 355 Hz 3 Hz 352 Hz r 358 Hz must be 358 Hz. Aswers t the Prblems i Prblem Slig. ( ) 2 33 K 343 m s 355 m s 293 K 233 K 343 m s 306 m s ( ) K m s 306 m s 49 m s m s 293 K 305 K 32 C 343 m s 2. ( )

6 Chapter 6 Sud ad Music d d 000 m 000 m t 2.92 s 0.20 s 2.72 s 343 m s 500 m s a i d d 800m 800m t 2.33 s s.8 s 343 m s 500 m s a w t 343 m s d 85.8 m 2 2 4Hz 6. d t ( ) ( ) 343 m s 2 s 686 m 90 db 0 db I I ( )( ) 0 0 W m 0 0 W m 4 2 I 0 W m β 0 db lg 0 db lg 0 db 8 80 db 2 2 I 0 W m 8. ( ) ( ) ( ) W m β 0 db lg 80 db W m 9. ( ) W m β 2 ( 0 db) lg 83 db W m β β2 β 3dB β 0 db I I 0 0 W m 0 0 W m β2 0 db I2 I 0 0 W m 0 0 W m 4 2 I2 0 W m I 0 W m 500 m s 47 Hz.2 m 500 m s 333 Hz.5 m.32 m.32 m, 0.66 m, 0.44 m,... ( 500 Hz) 500 Hz, 000 Hz, 500 Hz,....6 m.6 m, 0.8 m, m,... ( 375 Hz) 375 Hz, 750 Hz, 25 Hz, m s 2L 2m 72 Hz L 343 m s Hz m

7 98 Chapter 6 Sud ad Music m s 85.8 Hz 4L 4m 343 m s L 0.24 m Hz 340 m s 6.8 m 50 Hz 6.8 m d 2m 0.3m m s 0.97 m 350 Hz 350 Hz 7 50 Hz A ad B, therere A 2 B 2 40 cm 80 cm 2 4 utside 22. utside rm ad 2. L L L L ( ) rm utside 273 K utside rm ( 440 Hz) 425 Hz 293 K rm ± b 424 Hz ± 3 Hz 42 Hz r 427 Hz Hz 4 Hz 246 Hz r 254 Hz 255 Hz 9 Hz 246 Hz r 264 Hz must be 246 Hz. 700 Hz 644 Hz s Hz 639 Hz Hz s 40 ± ± Hz, 358 Hz 452 Hz 358 Hz 94 Hz 25. ( ) 26. ( ) 27. ( ) 40 ± 400 Hz ± 447 Hz, 353 Hz ( ) 447 Hz 353 Hz 94 Hz Hz 486 Hz s ( ) iit

8 Chapter 6 Sud ad Music 99 ial ( 400 Hz) 384 Hz + s Hz 420 Hz s ( ) iit ial ( 400 Hz) 384 Hz + s Hz ( 343 m s) 9.5 m s Hz Hz ( 343 m s) 0.78 m s Hz

4308 Friday, Period 3, 11:15 a.m. - 12:25 p.m.

4308 Friday, Period 3, 11:15 a.m. - 12:25 p.m. Sweet Adelies Iteratial F.A.C.E. IT, YOU'RE NOTEWORlHY Mary Elle Stepaich, Ph.D., OF 2004 Iteratial Educati Sympsium Less Pla Pagel CLASS TITLE: 4308 Friday, Perid 3, 11:15 a.m. - 12:25 p.m. CLASS DESCRIPTION: