Re: [Phys-l] standing wave experiment

["Rick Tarara" <rtarara@saintmarys.edu>]

----- Original Message ----- 
From: "John Denker" <jsd@av8n.com>
To: "Forum for Physics Educators" <phys-l@carnot.physics.buffalo.edu>
> If you suspect your string is too stretchy, you can take Henny
> Youngman's advice: don't do it that way.  Non-stretchy cordage
> is easy to come by.

Since (I believe) the problem here is that PASCO supplies (even sells) this 
string with their wave motion vibrators, one might think this is good stuff 
with which to work.  I bit and ordered a reel of the string when we bought 
the vibrators.  That reel remains sealed!  The big stretchy stuff is fine 
for showing standing waves (demo mode), but I prefer a 20ft long coiled 
spring for that.  I actually have not seen the reported behavior, but the 
stretching of the string makes the traditional experiment impossible since 
knowing the mass/length of the string becomes a function of the tension on 
the string.  Too complicated.  We have some 50 lb test fishing line (don't 
try and break that stuff with your hands or try the break the string by 
accelerating a mass having wrapped the string around your hand demo--been 
there, done that, OUCH!) that is thick enough to see well and doesn't 
stretch.  It works great in this lab.

Rick