Vibration, Waves, & Sound Test Review

Transcription

1 Vibration, Wave, & Sound Tet Review 1. Lit variable that affect the wing of a pendulum. See Pendulum Lab 2. Define the period of a pendulum. See Reading Quetion 3. Draw a tranvere wave and label the cret, amplitude, wavelength, and trough. See Wave Note 4. Draw a longitudinal wave and label the compreion and rarefaction. See Vibration & Wave Reading Quetion 5. Define wave peed in term of wavelength and frequency. See Wave Note 6. What do wave peed, wavelength, and frequency of a ound depend upon? See Wave Note 7. Define mechanical and electromagnetic wave. Give example. See Wave Note 8. Decribe the Doppler effect. See Doppler Effect Note 9. Give the equation for the Doppler effect and how to ue it. See Doppler Effect Note 10. Be able to determine the peed of a plane from the hock wave it create. See Workheet on the back of Loudne and Intenity 11. Define compreion and rarefaction. See Vibration & Wave Reading Quetion 12. What are the frequencie of AM and FM tation? See Sound Reading Quetion 13. What are the two poible unit of frequency? See Vibration & Wave Quetion 14. What type of a wave i a ound wave? See Sound Reading Quetion 15. What are the limit of human hearing? See Sound Reading Quetion 16. Define infraonic and ultraonic. See Sound Reading Quetion 17. What media tranfer ound the quicket? See Sound Reading Quetion 18. Define echo and reverberation. See Sound Reading Quetion 19. Decribe the refraction ound. See Sound Reading Quetion 20. How much energy do ound wave have? See Sound Reading Quetion 21. What happen to ound energy? See Sound Reading Quetion 22. What i a forced vibration? See Sound Reading Quetion 23. What i natural frequency? See Sound Reading Quetion 24. What i reonance? See Sound Reading Quetion 25. Decribe what happened to the Tacoma Narrow Bridge. You have to remember thi. 26. Define interference. See Sound Reading Quetion 27. Define beat. See Sound Reading Quetion 28. Define elaticity. See Sound Reading Quetion 29. How doe a radio wave differ from a ound wave? See Sound Reading Quetion 30. Decribe how you ued a reonance tube to meaure the peed ound. See Sound Lab 31. Decribe what tuning fork do to the urrounding medium. See Sound Lab 32. Decribe how to ue an echo to meaure the peed ound. See Sound Lab 33. Decribe how the computerized verion of a high pitch ound differ from the computerized verion of a low pitch ound. See Sound Lab 34. Decribe how the computerized verion of an orchetra ound different from a tuning fork. See Sound Lab 35. What medium conduct ound the fatet? See Sound Reading Quetion 36. Which ound travel further, high pitch or low pitch? See Sound Reading Quetion 37. Define intenity. See Loudne Note 38. Give a formula for ound intenity with appropriate unit. See Loudne Note 39. Define loudne. See Loudne Note 40. What i the threhold of hearing? See Loudne Note 41. Give the formula with appropriate unit for relative intenity. See Loudne Note 42. Why i relative intenity a logarithmic cale? See Loudne Note 43. Determine relative intenity given ound power and ditance from ource. See Loudne Note 44. Determine intenity given relative intenity. See Loudne Note 45. Draw a caled hock wave for a plane traveling fater than the peed ound. See workheet on back of Loudne & Intenity 46. Determine the peed of a uperonic plane from a caled drawing. See workheet on back of Loudne & Intenity 47. Give a formula for oberved frequency baed on the Doppler effect with appropriate uage. See Doppler Effect Note 48. Determine oberved frequencie, ource frequencie, oberver velocity, and ource velocity given the other 3 variable. See Doppler Effect Note Tet Review Problem (Ue 340 m/ a the peed ound in air.) 1. A wave ha a peed of 240 m/ and a wavelength of 3.2 m. What are the frequency and period of the wave? f = v λ = 24.0m / 3.2m = 75Hz T = 1 f = 1 75Hz = 0.013ec

2 2. A piano emit frequencie that range from a low of about 28 Hz to a high of about 4200 Hz. Find the range of wavelength panned by thi intrument. λ = v f λ = v f = 340m / 28Hz = 12m = 340m / 4200Hz = 0.081m 3. A ound wave i emitted by the foghorn of a tugboat. An echo i heard 2.6 later. How far away i the reflecting object? v = x t = 2d t d = 1 2 vt = 1 (340m /)(2.6ec) = 442m 2 4. The note middle C on a piano ha a frequency of approximately 264 Hz and a wavelength of 1.31 m. Find the peed ound in air. v = λf = (1.31m)(264Hz) = 346m / 5. An FM tation broadcat at a frequency of 100 MHz with a radio wave having a wavelength of 3 m. Find the peed of the radio wave. v = λf = (3m)(100x10 6 Hz) = 3x10 8 m / 6. The peed of electromagnetic wave in a vacuum i 3.0x10 8 m/. Wavelength of viible light wave range from about 400 nm in the violet to 700 nm in the red. What i the range of frequencie of light wave? (nanometer =10-9 m) f = v λ = 3x108 m / 400x10 9 m = 7.5x1014 m f = v λ = 3x108 m / 700x10 9 m = 4.3x1014 m 7. A group of hiker hear an echo 3 after they hout? How far away i the mountain that reflected the ound wave? v = x t = 2d t d = 1 2 vt = 1 (340m /)(3ec) = 510m 2 8. Earthquake S wave have a peed of 3000 m/. P wave have a peed of 5000 m/. P wave are detected 2.58 minute before S wave by a eimograph. How far i the earthquake' epicenter from the eimograph? t =t t p = d v d v p min(60ec/ min) = d 3000m / m / 154.8ec =d(1.33x10 4 ec/m) d = 1.16x10 6 m 9. Calculate the intenity level of a ound wave having an intenity of W/m 2, W/m 2, and W/m 2. I = 10log W /m 2 = 0dB I o W /m 2 I = 10log W /m 2 = 10dB I o W /m 2 I = 10log W /m 2 = 20dB I o W /m What i the intenity level in decibel of a ound wave of intenity 10-6 W/m 2? 10-5 W/m 2?

3 I = 10log W /m 2 I o W /m 2 = 60dB I I o = 10log W /m W /m 2 = 70dB 11. What i the intenity of a ound whoe intenity level i 40 db? 100dB? I I o I 40 = 10 log W /m 2 4 = logi log(10 12 W /m 2 ) I = 10 8 W /m 2 I 100 = 10log W /m 2 10 = logi log(10 12 W /m 2 ) I = 10 2 W /m The area of a typical eardrum i about 5.0x10-5 m 2. Calculate the ound power incident on an eardrum at the threhold of hearing. I = P A P =IA = (10 12 W /m 2 )(5.0x10 5 m 2 ) = 5.0x10 17 W 13. Repeat the calculation for the threhold of pain which i 120 db. I 120 = 10log W /m 2 I = 1.0W /m 2 I = P A P =IA = (1.0W /m 2 )(5.0x10 5 m 2 ) = 5.0x10 5 W 14. On a work day, the average decibel level of a buy treet i 70 db with 100 car/minute. If the number of car i reduced 25 car every minute on a weekend, what i the decibel level of the treet? I 100car 70dB =10 log W /m 2 I 100car =10 5 W /m 2 I 75car =.75(10 5 W /m 2 ) = 7.5x10 6 W /m 2.5x10 6 W /m 2 = 69dB W /m 2

4 15. A rather noiy typewriter produce a ound intenity of 10-5 W/m 2. Find the decibel level of thi machine and calculate the new decibel level when a econd identical typewriter i added to the office. I = 10log 10 5 W /m W /m 2 = 70dB I o I = 10log 2x10 5 W /m W /m 2 = 73dB I o 16. A mall ource emit ound wave with a power output of 80 W. Find the intenity 3 m from the ource. I = P A = P 4πr = 80W 2 2 = 0.71W /m2 4π(3m) 17. For the ound in the previou problem, find the ditance at which the ound level i 40 db. I 40 = 10log W /m 2 I = 10 8 W /m 2 = P 4πr 2 r = W π(10 8 W /m 2 ) = 25,231m 18. A train moving at a peed of 40 m/ ound it whitle, which ha a frequency of 500 Hz. Determine the frequency heard by a tationary oberver a the train approache. 1 ± v o v 1 1 v = 500Hz 40m / = 567Hz 1 v 340m / 19. An ambulance travel down a highway at a peed of 75 mi/h, it iren emitting ound at a frequency of 400 Hz. What i the frequency heard by a paenger in a car traveling at 55 mi/h in the oppoite direction a the car approache. 75 mile hour x 1610m mile x 1hour = 33.5m / 3600ec 55 mile hour x 1610m mile x 1hour = 24.6m / 3600ec 1 ± v o 24.6m / 1 + v 340m / 1 v = 400Hz 33.5m / 1 v 340m / = 476Hz 20. What frequency i heard by the car after it pae and move away from the ambulance? 1 ± v o 24.6m / 1 v 340m / 1 v = 400Hz 33.5m / = 338Hz 1+ v 340m / 21. A train at ret emit a ound at a frequency of 1000 Hz. An oberver in a car travel away from the ound at a peed of 30 m/. What i the frequency heard by the oberver?

5 1 ± v o 30m / 1 v 340m / 1 v = 1000Hz 1 = 912Hz v 22. The oberver in the previou problem top the car. Determine the frequency he hear when the train approache her at a peed of 30 m/ and when the train recede from her at a peed of 30 m/. 1 ± v o v 1 v 1 = 1000Hz 30m / =1098Hz 1 v 340m / 1 ± v o v 1 v 1 = 1000Hz 30m / = 919Hz 1 + v 340m / 23. An alert phyic tudent tand beide the track a a train roll lowly pat. She note that the frequency of the train whitle i 442 Hz when the train i approaching her and i 441 Hz when the train i receding from her. What hould thi alert phyic tudent determine the peed of the train to be?

6 1 ± v o v 1 m v v Hz v 1 and 441Hz v 340m / m / 442Hz 441Hz = 1 f v 1 340m / 1 f v m / v = 340m / v 1 340m / v v 340m / = m / v = 340 +v = v v = m /