PHYS 102 Quiz Problems Chapter 17 : Sound Waves Dr. M. F. Al-Kuhaili 1. (TERM 001) 2. (TERM 001) 3. (TERM 002) 4. (TERM 002) 5.

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1 PHYS 102 Quiz Prblems Chapter 17 : Sund Waves Dr. M. F. Al-Kuhaili 1. (TERM 001) A mving train is blwing a whistle at 500 Hz. An bserver at rest hears the sund at 480 Hz. What is the speed f the train, and in what directin is the train mving relative t the bserver? 2. (TERM 001) A pint surce emits sund waves with an average utput pwer f 8.0 W. An bserver recrds a sund level β f 100 db. What is the distance between the surce and the bserver? 3. (TERM 002) A sund wave f frequency 1000 Hz is prpagating thrugh air. (a) What is the wavelength? (b) A tube pen at bth ends has this frequency as a fundamental. Hw lng is the tube? 4. (TERM 002) A tube clsed at ne end resnates at 7.00 Hz and at n lwer frequency. The air in the tube has a density f 1.0 kg/m 3 and a bulk mdulus f Pa. Hw lng is the tube? 5. (TERM 002) Tw trains are traveling tward each ther with a speed f 100 m/s. One train is blwing a hrn at 500 Hz. What frequency will be heard n the ther train? 6. (TERM 002) A pint surce emits sund waves with a pwer utput f 80.0W. (a) What is the intensity at a distance f 3.00 m frm the surce? (b) What is the distance at which the sund level is 40 db? 7. (TERM 012) A pint surce S, lcated at the rigin, emits sund in all directins with a wavelength f 0.35 m. A detectr at P 1 recrds a sund level f 100 db. (a) What is the frequency f the sund emitted by the surce? (b) What is the pwer f the surce? (c) What is the intensity f sund at P 2? (d) What is the amplitude f the air scillatins at P 2? [Speed f sund in air = 343 m/s, density f air = 1.21 kg/m 3, I = W/m 2 ] 8. (TERM 012) A sund wave f frequency 1000 Hz prpagating thrugh air has a pressure amplitude f 10.0 Pa. (a) What is the wavelength f this wave? (b) What is the particle displacement amplitude? (c) What is the maximum particle speed? (d) A pipe, clsed at ne end, has this frequency as a fundamental. Hw lng is the pipe?

2 9. (TERM 012) A car mving t the right at a speed f 10.0 m/s fllws a fire truck. The fire truck emits sund with frequency f 500 Hz. The van is at rest, and a passenger in the van recrds a frequency f 520 Hz fr the sund emitted by the fire truck. (a) What is the speed f the fire truck? (b) What frequency will be recrded by a passenger in the car fr the sund emitted by the fire truck? 10. (TERM 021) A pint surce emits sund waves istrpically in air with a frequency f 500 Hz. An bserver 3.0 m frm the surce measures a sund level f 80 db. (a) Calculate the average pwer utput f the surce. (b) Calculate the displacement amplitude f air mlecules due t this wave. (c) Calculate the pressure amplitude f this wave. 11. (TERM 021) An ambulance travels dwn a highway at a speed f 35 m/s. Its siren emits sund at a frequency f 500 Hz. What is the frequency heard by a passenger in a car traveling at 25 m/s in the ppsite directin as the car appraches the ambulance and as the car mves away frm the ambulance? 12. (TERM 022) A vibratr is used t generate sund waves in a tube clsed at ne end. Tw resnant frequencies are heard at 52.0 Hz and 60.0 Hz. (a) What is the length f the tube? (b) What is the fundamental frequency f the tube? 13. (TERM 022) Tw sund surces, separated by a distance f 2 m, are in phase and emit sund waves with a frequency f 500 Hz. Pint A is 0.3 m frm S 1 and pint B is 1.5 m frm S 1. (a) What is the phase difference between the tw sund waves at pint A? (b) What is the phase difference between the tw sund waves at pint B? (c) At which pint is the sund luder, why? 14. (TERM 022) A statinary bserver recrds a frequency f 600 Hz frm the siren f an appraching plice car. After the plice car passes, the bserved frequency f the siren is 480 Hz. What is the speed f the plice car? 15. (TERM 033) A pint surce f sund has a pwer f 1.0 mw and emits sund waves at a frequency f 500 Hz. (a) What is the intensity (I) at a distance f 3.0 m away frm the surce? (b) What is the sund level (β) at that distance? (c) What is the amplitude f the air scillatins (S m ) caused by this wave?

3 16. (TERM 042) A by n a bicycle appraches a wall as he sunds his hrn at a frequency f. The sund he hears reflected back frm the wall is at a frequency 1.05 f. What is the speed f the bicycle? Assume the speed f sund in air is 343 m/s. 17. (TERM 042) A tube is clsed at ne end and pen at the ther end. The tube is cut int tw pieces. After cutting, the lwest resnant frequency is 250 Hz fr the piece with the clsed end, and 600 Hz fr the piece that is pen at bth ends. (a) What was the length f the riginal tube? (b) What was the fundamental frequency f the riginal tube? 18. (TERM 042) Tw speakers face each ther as shwn in the figure belw. They are separated by a distance f 5.0 m, and each speaker has a pwer utput f W/m 2. Pint P is alng the line jining the tw surces at a distance f 2.0 m frm speaker A. What is the sund level (β) at pint P? 19. (TERM 052) A statinary sund surce (S) emits sund waves with frequency f. An bserver is mving at a speed f 10 m/s. The bserver recrds a frequency f1 as he appraches S and a frequency f2 as he mves away frm S. The difference between f 1 and f 2 is 36 Hz. What is the value f f? Take the speed f sund in air t be 340 m/s. 20. (TERM 052) A tube is clsed at ne end and pen at the ther end. A standing sund wave is set up in the tube with 4 antindes. The distance between tw ndes is 12.5 cm. (a) What is the harmnic number f this wave? (b) What is the wavelength f sund? (c) What is the frequency f sund? (d) What is the length f the tube? 21. (TERM 052) Tw speakers, separated by a distance d 1 = 3.00 m, are in phase and emit sund waves with a frequency f 544 Hz. A listener is initially at pint A, which is a distance d 2 = 4.00 m in frnt f ne f the speakers. Nw, the listener starts t mve frm pint A t pint B alng a line parallel t the line jining the tw speakers. Hw many maxima and minima will he bserve? 22. (TERM 061) A pint surce f sund has a pwer W. a. What is the intensity 5.00 m frm the surce? b. What is the sund level at that distance?

4 23. (TERM 061) An ambulance emitting sund is passing by a standing bserver. As the ambulance appraches him, its frequency (as heard by the bserver) is 550 Hz. The speed f the ambulance is 16 m/s. a. What is the frequency f the sund emitted by the ambulance? b. What frequency will be heard by the bserver as the ambulance mves away? 24. (TERM 062) A surce f sund waves has a pwer f 1.50 µw. A listener is at pint X, which is a distance f 3.00 m frm the surce. a) What is the intensity f sund at pint X? b) What is the sund level at pint X? 25. (TERM 061) Tube A, which is pen at ne end nly, is cut int tw equal pieces B and C, as shwn belw. The fundamental frequency f tube B is 200 Hz. a. What is the length f tube B? b. What is the fundamental frequency f tube A? c. What is the fundamental frequency f pipe C? 26. (TERM 062) Tw speakers are placed 2.00 m apart and are driven by the same amplifier, as shwn in the figure belw. They emit sund with a frequency f 505 Hz. Starting at the midpint P, a detectr is mved alng the line jining the tw detectrs twards speaker A. Hw far (frm the midpint) shuld the detectr mve t bserve the first minimum? The speed f sund in air is 343 m/s. 27. (TERM 062) A tube is pen at ne end and clsed the ther end. Tw cnsecutive resnant frequencies f the tube were fund t be 550 Hz and 650 Hz. The speed f sund in air is 343 m/s. a. What is the length f the tube? b. What is the fundamental frequency f the tube? c. what is the harmnic number (n) f the 550 Hz frequency? 28. (TERM 063) The sund intensity (I) at a distance f 4.0 m frm a sund surce is 72 W/m 2. What is the sund level (β) at a distance f 9.0 m frm the surce? 29. (TERM 063) A tube has a length f 1.20 m. a) What is the fundamental frequency f the tube if it is pen at bth ends? b) What is the fundamental frequency f the tube if it is pen at ne end and clsed at the ther end? 29. (TERM 071) A sund surce has a pwer utput f mw. (a) What is the intensity (I) f sund at a distance f 5.00 m frm the surce? (b) What is the sund level (β) at that distance?

5 30. (TERM 071) Tw sund surces are driven by the same generatr. A detectr is at a distance f 29.0 m frm ne surce, and a distance f 25.0 m frm the ther surce. The frequency is varied between 20 Hz and 200 Hz. At what frequencies will the detectr bserve maximum intensity? 31. (TERM 071) An ambulance is mving at a speed f 15 m/s and emits sund with a frequency f 350 Hz. A car is driving in the ppsite directin, as shwn in the figure belw, at a speed f 12 m/s. What frequency will be detected by the driver f the car? Ambulance 15 m/s 12 m/s car