momentum of sound

[Bryden, Francis]

The way I think of it is that sound transfers energy but not momentum.
The individual air molecules have momentum, but for every molecule with
+p there is another with -p. I suppose its possible for a compression to
knock something over before the rarefaction has had time to pull it back

 

On  a related note. Many of you will have seen an "airzooka" that fires
a toroid of air across the room. There is a transfer of air on this
case, but why is it different to a loudspeaker that just vibrates the
air

 

 

 

 

 

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: 63 9 5204159 ext 7808

 

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

-----Original Message-----
From: phys-teach-talk-bounces at nzip.org.nz
[mailto:phys-teach-talk-bounces at nzip.org.nz] On Behalf Of John Bull
Sent: Monday, 10 March 2008 8:18 a.m.
To: phys-teach-talk at nzip.org.nz
Subject: momentum of sound

 

At the risk of sounding dumb on Monday morning - can someone tell me
whether sound has momentum, and if not - why not? (since it is moving
particles) . This was a student's question relating to an experiment of
an air rifle pellet hitting a block of wood.

 

cheers

 

John Bull

St John's College 

Hamilton
 
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