197559
Theory of sonics : applications Elementary physical principles If v is the velocity of which waves travel along the pipe , and n the number of the revolutions of the crank a The wavelength λ is = v/n Assuming that the pipe is finite and closed at the point r situated at a distance which is multiple of λ , and considering that the piston is smaller than wavelength , at r the wave compression is stopped and reflected , the reflected wave traveling back along the pipe .
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Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
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