Keyweights and moment of inertia

[Richard Moody]

Rob, Robert, List
	 

> Also, does anyone
> make a device that measures total moment of inertia?
> 
> Bob Scott

The question is can moment of intertia be measured? If so, so what?  This
is where I get stalled in physics. Newton says that force equals mass
times acceleration. Now  another law Newton came up with says that a
body (mass) in motion will keep that same motion unless acted on by other
forces. 
But here acceleration is zero, so does that mean a body in motion has no
force?  
	But where I flunk out in physics is asking the question "if a body in
motion has no acceleration, then what happens to the formula f=ma ?"  (a =
0 )  From that I suppose there is a formula that should read x=mv.  here m
= mass and v = velocity, but what then is x  ? 

	So to put it in perspective,  I would suggest to forget about the "laws"
of "moment of interia" as far as piano technology is concerned. Where ever
the weight is placed on the key, I suspect these "laws" would predict an 
effect close to zero.   As far as the player is concerned and how the key
pressing down to him feels...what counts more, the praise of the player,
or the plaudits of physisysts? 

Ricisyst
.. 


----------
> From: Robert Scott <rscott@wwnet.net>
> To: pianotech@ptg.org
> Subject: Keyweights and moment of inertia
> Date: Wednesday, October 07, 1998 9:17 AM
> 
> Rob Kiddell wrote:
> 
> >    Recently, I published  an article on grand piano action 
> > diagnosis, and one of the conclusions I came to was re-balancing 
> > keys with many 1/2" leads per key. Basically I remove larger leads 
> > near the balance rail and insert smaller leads near the end of the 
> > key. This seems to make the actions feel inertially lighter, and 
> > there is less 'thumping' from heavy keys on balance rails. However, 
> > it was brought to my attention that (I quote here)
> 
> >   When the key is moving the "moment" of inertia becomes much 
> >   more important. Unfortunately it is affected by the distance
> >   from the balance rail by a factor of R squared.
>