Re: [Harp-L] Re: Reed Stress and Temperature

[Vern <jevern@xxxxxxx>]

I suppose that I should not have used “elasticity” when referring to the “modulus of elasticity, Young’s modulus, E, stress divided by strain”. Stress is pounds per square inch of cross-section and strain is inches of stretch per inch of length.  For brass, E is about 15.5 million pounds per square inch (PSI)  For steel, it is greater.  It is the same kind of animal but has a different numerical value in metric units.

E is greater at lower temperatures.  i.e. an equal amount of stretch produces a greater restoring force at lower temperatures. If you are thinking of “elasticity” as the ease with which something stretches, then my usage is indeed misleading.

Vern

On Sep 24, 2014, at 11:57 AM, Joseph Leone <3n037@xxxxxxxxxxx> wrote:

> I would have thought the opposite. As a metal expands, don't the molecules get farther apart? Making the metal softer. Until the metal finally melts. 
> Doesn't cooling force the molecules closer together. Making the metal tighter? How does tighter equate to 'more elasticity'? Doesn't seem to jive.
> 
> smo-joe 
> 
> On Sep 24, 2014, at 1:23 AM, Vern wrote:
> 
>> 
>> On Sep 23, 2014, at 3:52 PM, patpowers <patpowers@xxxxxxx> wrote:
>> 
>>> Thanks Vern - I love a good debate! ;)
>>> 
>>> …….., but my point is all materials get stiffer, and lose elasticity, as temperature decreases.
>> 
>> They gain elasticity (the value of E goes up) as the temperature decreases.
>> 
>