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 > +++++++++++++++++++++ > _______________________________________________ > pianotech list info: https://www.moypiano.com/resources/#archives
This PTG archive page provided courtesy of Moy Piano Service, LLC