Key Leads and Inertia

[Joe And Penny Goss]

And all of it adding to global warming <G> STDMMDI
Joe Goss
imatunr@srvinet.com
www.mothergoosetools.com
----- Original Message ----- 
From: "Bill Ballard" <yardbird@vermontel.net>
To: "Pianotech" <pianotech@ptg.org>
Sent: Friday, June 13, 2003 8:51 PM
Subject: Re: Key Leads and Inertia


> At 6:00 AM -0400 6/13/03, Mark Davidson wrote:
> >So far I like David's point best, that 85% of the energy goes into the
> >hammer.  That means a 10% variation in key inertia becomes only
> >a 1.5 variation in ....something.  Need more coffee.
> 
> Went to re-heat my coffee. Let me toss this in. Of the three main 
> force in a piano action, friction, gravity and inertia, friction is 
> the only opposing force which actually removes a significant portion 
> of energy from the system. Both gravity and inertia store and return 
> an appreciable amount of energy to the system on the return stroke. 
> Lift the hammer up and when you remove your finger from the key, 
> gravity is there to make the parts swing back down. With inertia, the 
> extra force required in lifting a heavier hammer is stored as 
> potential in the parts' angular momentum. When the stroke slams to an 
> end, the rotational kinetic energy is transferred to the string (and 
> the mass of felt fibers) and is promptly reflected/returned to the 
> parts.
> 
> When energy is lost to friction, that energy is actually only 
> converted to heat. In a piano action, we don't see a whole lot of 
> thermal energy converted back into kinetic.
> 
> Bill Ballard RPT
> NH Chapter, P.T.G.
> 
> "Out here on the food chain, you either          
>     diet,die, or dine"
>      ...........folksinger Mark Graham
> +++++++++++++++++++++
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