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A piano tuner hears a beat every 2.00 s when listening to a 264.0-Hz tuning fork and a single piano string. What are the two possible frequencies of the string?

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(a) What is the fundamental frequency of a 0.672-m-long tube, open at both ends, on a day when the speed of sound is 344 m/s? (b) What is the frequency of its second harmonic?

(a) 256 Hz

(b) 512 Hz

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If a wind instrument, such as a tuba, has a fundamental frequency of 32.0 Hz, what are its first three overtones? It is closed at one end. (The overtones of a real tuba are more complex than this example, because it is a tapered tube.)

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What are the first three overtones of a bassoon that has a fundamental frequency of 90.0 Hz? It is open at both ends. (The overtones of a real bassoon are more complex than this example, because its double reed makes it act more like a tube closed at one end.)

180 Hz, 270 Hz, 360 Hz

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How long must a flute be in order to have a fundamental frequency of 262 Hz (this frequency corresponds to middle C on the evenly tempered chromatic scale) on a day when air temperature is 20.0ºC ? It is open at both ends.

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What length should an oboe have to produce a fundamental frequency of 110 Hz on a day when the speed of sound is 343 m/s? It is open at both ends.

1.56 m

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What is the length of a tube that has a fundamental frequency of 176 Hz and a first overtone of 352 Hz if the speed of sound is 343 m/s?

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(a) Find the length of an organ pipe closed at one end that produces a fundamental frequency of 256 Hz when air temperature is 18.0ºC . (b) What is its fundamental frequency at 25.0ºC ?

(a) 0.334 m

(b) 259 Hz

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By what fraction will the frequencies produced by a wind instrument change when air temperature goes from 10.0ºC to 30.0ºC ? That is, find the ratio of the frequencies at those temperatures.

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The ear canal resonates like a tube closed at one end. (See [link] .) If ear canals range in length from 1.80 to 2.60 cm in an average population, what is the range of fundamental resonant frequencies? Take air temperature to be 37.0ºC , which is the same as body temperature. How does this result correlate with the intensity versus frequency graph ( [link] of the human ear?

3.39 to 4.90 kHz

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Calculate the first overtone in an ear canal, which resonates like a 2.40-cm-long tube closed at one end, by taking air temperature to be 37.0ºC . Is the ear particularly sensitive to such a frequency? (The resonances of the ear canal are complicated by its nonuniform shape, which we shall ignore.)

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A crude approximation of voice production is to consider the breathing passages and mouth to be a resonating tube closed at one end. (See [link] .) (a) What is the fundamental frequency if the tube is 0.240-m long, by taking air temperature to be 37.0ºC ? (b) What would this frequency become if the person replaced the air with helium? Assume the same temperature dependence for helium as for air.

(a) 367 Hz

(b) 1.07 kHz

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(a) Students in a physics lab are asked to find the length of an air column in a tube closed at one end that has a fundamental frequency of 256 Hz. They hold the tube vertically and fill it with water to the top, then lower the water while a 256-Hz tuning fork is rung and listen for the first resonance. What is the air temperature if the resonance occurs for a length of 0.336 m? (b) At what length will they observe the second resonance (first overtone)?

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What frequencies will a 1.80-m-long tube produce in the audible range at 20.0ºC if: (a) The tube is closed at one end? (b) It is open at both ends?

(a) f n = n ( 47.6 Hz ) , n = 1, 3, 5,..., 419

(b) f n = n ( 95.3 Hz ) , n = 1, 2, 3,..., 210

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Practice Key Terms 5

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Source:  OpenStax, College physics. OpenStax CNX. Jul 27, 2015 Download for free at http://legacy.cnx.org/content/col11406/1.9
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