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On the note emitted from a mug while mixing instant coffee

Published online by Cambridge University Press:  24 October 2008

W. E. Farrell
Affiliation:
Institute of Geophysics and Planetary Physics, University of California, San Diego, La Jolla, California
D. P. McKenzie
Affiliation:
Institute of Geophysics and Planetary Physics, University of California, San Diego, La Jolla, California
R. L. Parker
Affiliation:
Institute of Geophysics and Planetary Physics, University of California, San Diego, La Jolla, California

Extract

We have recently observed a curious phenomenon, undoubtedly well known, while mixing instant coffee in a mug. If the bottom of the mug was tapped repeatedly with the spoon as the powder was stirred into the water, the note emitted could be heard to rise in pitch by over an octave. This rise occurred in a matter of seconds, about the same time as it took the mug to heat up. Further experimentation showed that almost any powder could produce the effect in cold or hot water, but water alone would not. Vigorous stirring did not seem essential. A full mug showed as pronounced an effect as a half-filled one.

Type
Research Article
Copyright
Copyright © Cambridge Philosophical Society 1969

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References

REFERENCE

(1)Landau, L. D. and Lifshitz, E. M.Theory of elasticity. (Pergamon Press; London, 1959).Google Scholar