Concept explainers
Example 16.1 (Section 16.1) showed that for sound waves in air with frequency 1000 Hz, a displacement amplitude of 1.2 × 10−8 m produces a pressure amplitude of 3.0 × 10−2 Pa. (a) What is the wavelength of these waves? (b) For 1000-Hz waves in air, what displacement amplitude would be needed for the pressure amplitude to be at the pain threshold, which is 30 Pa? (c) For what wavelength and frequency will waves with a displacement amplitude of 1.2 × 10−8 m produce a pressure amplitude of 1.5 × 10−3Pa?
Want to see the full answer?
Check out a sample textbook solutionChapter 16 Solutions
University Physics with Modern Physics, Volume 2 (Chs. 21-37); Mastering Physics with Pearson eText -- ValuePack Access Card (14th Edition)
Additional Science Textbook Solutions
College Physics
Glencoe Physical Science 2012 Student Edition (Glencoe Science) (McGraw-Hill Education)
The Cosmic Perspective Fundamentals (2nd Edition)
University Physics (14th Edition)
Cosmic Perspective Fundamentals
- Some studies suggest that the upper frequency limit of hearing is determined by the diameter of the eardrum. The wavelength of the sound wave and the diameter of the eardrum are approximately equal at this upper limit. If the relationship holds exactly, what is the diameter of the eardrum of a person capable of hearing 20 000 Hz? (Assume a body temperature of 37.0C.)arrow_forwardThe area of a typical eardrum is about 5.00 X 10-5 m2. (a) (Calculate the average sound power incident on an eardrum at the threshold of pain, which corresponds to an intensity of 1.00 W/m2. (b) How much energy is transferred to the eardrum exposed to this sound lor 1.00 mill?arrow_forwardConsider detectors of water waves at three locations A, B, and C in Active Figure 13.23b. Which of the following statements is true? (a) The wave speed is highest at location A. (b) The wave speed is highest at location C. (c) The detected wavelength is largest at location B. (d) The detected wavelength is largest at location C. (e) The detected frequency is highest at location C. (f) The detected frequency is highest at location A.arrow_forward
- How to convert 0.5 µW to dBSIL? (1 W = 1 000 000 µW).arrow_forwardAn interface is formed between a block of aluminium (with an acoustic impedance of 1.8 x 107 kg m2 s') and a block of copper (with an acoustic impedance of 4.6 x 107 kg m-2 s-1). Longitudinal sound waves travelling through the aluminium are normally incident on the boundary, and are partially reflected. a) What is the ratio of the amplitude of the reflected wave to that of the incident wave? Number b) What is the ratio of the amplitude of the transmitted wave to that of the incident wave? Number c) What percentage of the incident power is transmitted? Number d) What percentage of the incident power is reflected? Number % Ouit P Sove Questiarrow_forwardA speaker is producing spherically symmetric sounds with a total power of 88.5 W. If the speaker is located at the centre of a sphere with a radius of 2.20 m, what is the power received on a 1.70 m by 1.50 m area on the sphere? Give your answer in Watts to 2 decimal places.arrow_forward
- We know that in a sound wave there are three associated waves: a longitudinal displacement wave, a pressure wave and a density wave. Assuming that the displacement wave is harmonica: y(x,t)=y0sin(kx-ωt) where y0 is the displacement amplitude. (a) determine the expression of the pressure wave p(x,t) (b) of the pressure wave expression identifies the amplitude or maximum pressure value pmax, shows that it can be written as: pmax = ρv0ky0 where v0 is the phase velocity of the wave and ρ the density of the gas (c) if the sound weaker than a person can hear at the frequency of 400 Hz corresponds to a pressure amplitude of approximately 8 x 10-5 Pa, what is the corresponding amplitude of displacement. Suppose the gas is air whose density it is ρ=1.3 kg/m3 and the phase velocity of sound in air is v0 = 340m/sarrow_forwardProblem 7: An audio engineer takes decibel readings at distances of r1 = 11 m and r2 = 25 m from a concert stage speaker during a sound check. When he is r1 from the speaker, the engineer registers a decibel level of β1 = 103 dB on his loudness meter.Randomized Variables r1 = 11 mr2 = 25 mβ1 = 103 dBPart (a) What is the intensity of the sound, I1, in watts per square meter, that is measured by the loudness meter when the engineer is a distance of r1 from the speaker? Part (b) How much power P, in watts, is coming from the speaker during the sound check at distance r1? Part (c) Assuming that the speaker output does not change between the two measurements at r1 and r2, what sound intensity level β2, in decibels, will the loudness meter report when the engineer is at a distance r2 from the speaker?arrow_forwardB8arrow_forward
- Sound waves travel at roughly 340 m/s at room temperature. The minimum hearing range of a human is 20Hz. a) What is the wavelength of this wave? b) Could this wavelength fit inside the dimensions of Room 411( room dimensions are roughly 11.5 m x 8.7 m)? Justify your answer with sound reasoningarrow_forward10-11. You have been asked to evaluate the A-weighted sound level of a new model lawn mower and make a recommendation on an acceptable noise spectrum to achieve 74 dBA. Three approaches are being considered by the manufacturer: (1) an improved muffler that will reduce the sound level 3 dB in each frequency band, (2) a reduction in the speed of the mower that will reduce the sound level 5 dB in each frequency band, and (3) an engine redesign that will reduce the sound level 15 dB in the five highest frequency bands. Using a spreadsheet program you have written, compute the A-weighted sound level for the sound spectrum shown on the following page and develop a recommended noise spectrum based on the manufac- turer's alternatives that results in a sound level of less than 74 dBA. Assume that each of the alternative reductions may be added together (by decibel addition) in each frequency band in which it is applicable. 775 NOISE POLLUTION Band center Band level frequency (Hz) (dB) 63 78…arrow_forward(a) What is the speed of sound in a medium where a 100-kHz frequency produces a 5.96-cm wavelength? (b) Which substance in Table 17.1 is this likely to be?arrow_forward
- Principles of Physics: A Calculus-Based TextPhysicsISBN:9781133104261Author:Raymond A. Serway, John W. JewettPublisher:Cengage LearningPhysics for Scientists and Engineers, Technology ...PhysicsISBN:9781305116399Author:Raymond A. Serway, John W. JewettPublisher:Cengage Learning