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When we swing a stick in air (one way.. not back and forth), we hear sound if we swing it fast enough. Is the reason we hear it because by swinging fast enough we also make the amplitude of sound wave larger or we change the frequency of sound by doing that? (or both)

I know that the source determines the frequency of any kinds of waves. What exactly determines the frequency of sound in this example and how?

I'm a bit confused because we are not swinging it back and forth.

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when you are quickly pushing the stick through the air in one direction only- and not vibrating it back and forth- the wooshing sound you hear is made by the movements of air parcels that get swirled around by the fast passage of the stick, and dragged along in its wake. Since the size and speed of any given small volume of air that was disturbed and pushed around by the stick's motion are unpredictable, the sum total of the sound waves produced is a more or less random signal, consisting of a broad range of different (mostly high) frequencies called white noise.

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  • $\begingroup$ can we say that the faster we move the stick (one way)the larger the uncertainty in frequency? $\endgroup$ – physicsguy19 Mar 9 '19 at 16:05
  • $\begingroup$ no, the faster we move the stick, the higher the frequency of the wave. $\endgroup$ – niels nielsen Mar 9 '19 at 19:23
  • $\begingroup$ I meant the number of different frequencies that make the sound. $\endgroup$ – physicsguy19 Mar 9 '19 at 19:26
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    $\begingroup$ I see. the faster the stick gets moved, the stronger the waves become, and the greater the high-frequency content becomes. $\endgroup$ – niels nielsen Mar 9 '19 at 19:29

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