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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