MadSci Network: Physics

Subject: Hot Chocolate and rising pitch when tapping on bottom of cup

Date: Wed Nov 27 13:05:46 1996
Posted by: Michael R. Burkley
Grade level: other
School/Organization: No school given.
City: Niagara Falls State/Province: NY 14305
Country: usa
Area of science: Physics
Message ID: 849121546.Ph
If you take a cup of hot chocolate (other hot liquids with some slightly 
increased viscosity over water will exhibit the following property as
well) and tap the bottom of the cup with a spoon you will hear a
gradually rising tone (rising pitch of the taps).  The pitch reaches
a certain point and then stops rising.  Upon even a slight stirring the
pitch of the tapping lowers to its original level and begins to rise
again.  Stir, and then wait a minute, and the pitch level begins at the
higher level.

Any suggestions what causes this pitch rise?  I thought it might be
air encorporated into the liquid, though I don't think so, as even
very gentle stirring leads to the tone drop.  I also thought that it
might be the particles of chocolate settling out, though, again, I don't
think so (there doesn't seem to be time for that, and it works for 
liquids that don't settle (like hot tea and milk).

Interesting!  I look forward to hearing from you!


Michael Burkley
ex-Polyurethane Research Chemist
Current Pastor of the Niagara Presbyterian Church

Re:Hot Chocolate and rising pitch when tapping on bottom of cup

Current Queue | Current Queue for Physics | Physics archives

Try the links in the MadSci Library for more information on Physics. MadSci Home

MadSci Home | Information | Search | Random Knowledge Generator | MadSci Archives | Mad Library | MAD Labs | MAD FAQs | Ask a ? | Join Us! | Help Support MadSci

MadSci Network
© Copyright 1996, Washington University. All rights reserved.