Key Inertia

[Richard Brekne]

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Sarah Fox wrote:

> Hi Ric,
>
> > Ok Sarah... same kinetic energy.... but you demonstrated quite clearly below
> the
> > effect this (same energy for differeing mass* velocitycan have on what
> happenes
> > to the velocity of whats being hit.
> >
> > So what now ?
>
> Soooo....  You're right.  I was trying to simplify, and this argument
> assumes no impedance differences between the hammer and string.  However,
> when you introduce considerations of mechanical impedance (which what I did
> with the bowling ball/marble argument -- and which is the point you're
> raising now), there are indeed differences in efficiency from
> adding/removing mass to/from the hammer.  I discussed this in another
> posting, specifically with regard to impedance matching between the hammer
> and string.  I really don't have any feel for how big an effect this would
> be.
>
> ------------------

Yes... welll... now it seems to me that I have been basically right on target
all along...except that I have been using the term inertia erroneously...
however.. if you plug what my understanding of the term was, into most of what I
have written the past few days... things begin to sound more reasonably.  In the
end tho.... I find myself lacking a term or quantity for something I think would
be valuable to know... or have a number to put on... that is exactly the result
of a given mass at a given velocity. Cant use  mass * velocity in itself... as
you could come up with lots of same product for different factors....

 So what quantity do we have that is mass times velocity.... but is clearly
differentiates between each equal product...

Clearly... 2 x 2 does not equal 4 x 1..... at least in the case of  how much
mass at what speed hits any given other mass.

What quantity am I looking for here ?



> Somewhat off the subject, but still related, Mark wrote:
>
> >>So, how to explain Ric's example that the favorite action of his
> >>students has a SWR of 6.2 and is 'heavy in a good way'.  How high is
> >>too high?
>
> Yeah, that's it!  That's my Wissner!  That's the "good" sort of "heavy" I
> was trying to describe!  I wish I could try out your worn out piano there in
> Norway to see if it's my worn-out Wissner's long-lost twin.  :-)
>
> I submit to all of the friction proponents on this list that pianists don't
> *necessarily* like friction!  ;-)
>
> Peace,
> Sarah
>

Well.. can see I will have to publish all the data I can get on this action. I
will be taking it apart in the next few days so I have the opportunity to
measure things for you. But as far as your last sentence there.... Evidently our
friends at Steinway have come to this conclusion as well...  we just had a long
thread on Steinways new view on friction... and it was very much on the light
side.

Cheers
RicB



--
Richard Brekne
RPT, N.P.T.F.
UiB, Bergen, Norway
mailto:rbrekne@broadpark.no
http://home.broadpark.no/~rbrekne/ricmain.html
http://www.hf.uib.no/grieg/personer/cv_RB.html


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