HW-Ch17 - HW-CH17 9th Edition CH17 Problems: 20, 28, 52,...

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Unformatted text preview: HW-CH17 9th Edition CH17 Problems: 20, 28, 52, 64, 102 8th Edition CH17 Problems: 22, 26, 52, 62, 106 20. Figure 17-38 shows four isotropic point sources of sound that are uniformly spaced on an x axis. The sources emit sound at the same wavelength and the same amplitude sm , and they emit in phase. A point P is shown on the x axis. Assume that as the sound waves travel to P , the decrease in their amplitudes is negligible, What multiple of sm is the amplitude of the net wave at P if distance d in the ...gure is (a) =4, (b) =2, and (c) ? transmitting medium at any distance r from the source: b t); s = sin k(r r where b is a constant. Consider the speed, direction of propagation, periodicity, and intensity of the wave. (b) What is the dimension of the constant b? 28. Two sounds dier in sound level by 1.00 dB. What is the ratio of the greater intensity to the smaller intensity? 52. A tuning fork of unknown frequency makes 3.00 beats per second with a standard fork of frequency 384 Hz. The beat frequency decreases when a small piece of wax is put on a prong of the ...rst fork. What is the frequency of this fork? 64. A stationary detector measures the frequency of a sound source that ...rst moves at constant velocity directly toward the detector and and then ( after passing the detector) directly away from it. The emitted frequency is f. During the ap0 proach the detected frequency is fapp and during 0 0 0 the recession it is frec . If (fapp frec )=f = 0:500, what is the ratio s = of the speed of the source to the speed of sound? 102. A sound wave travels out uniformly in all directions from a point source. (a) Justify the following expression for the displacement s of the 1 ...
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This note was uploaded on 05/14/2011 for the course ECON 101 taught by Professor Asdaf during the Spring '11 term at Universidad de San Buenaventura Bogota.

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