sound in glass

[David Housden]

Hi Francis

I have just tried a similar expt with a glass mug (school issue!!) - I get
the opposite result - used a simple FFT application to see the frequencies
etc.  Bizarre!!

I remember a similar expt presented in Jearl Walker's book "The flying
circus of physics" in which he asks why the frequency changes (while tapping
on the side of the cup) during the process of adding instant coffee or milk
to hot water.  I believe this is due to a change in velocity (due to
air-filled water having a lower speed of sound than the non airfilled).
Maybe this would be a good IYPT problem??

Cheers

David

 

 

From: phys-teach-talk-bounces at nzip.org.nz
[mailto:phys-teach-talk-bounces at nzip.org.nz] On Behalf Of Bryden, Francis
Sent: Monday, 30 June 2008 2:44 p.m.
To: phys-teach-talk at nzip.org.nz
Subject: 

 

When you tap a glass beaker with a spoon you get a high frequency sound. 

Can anyone explain why the frequency drops when you pour in water

 

Thanks ................ Francis

 

Francis Bryden

HoD Physics

St Cuthbert's College

122 Market Rd               or Box 26 020

Epsom                              Epsom

Auckland 1051                   Auckland 1344

New Zealand                      New Zealand

 

ph: 64 9 5204159 ext 7808

 

 <mailto:fbryden at stcuthberts.school.nz> fbryden at stcuthberts.school.nz

 

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