This is a multi-part message in MIME format. ---------------------- multipart/alternative attachment I may not know much about pianos, but I know a little about physics! = Comments below: Terry Farrell =20 ----- Original Message -----=20 From: "Richard Brekne" <Richard.Brekne@grieg.uib.no> To: "Pianotech" <pianotech@ptg.org> Sent: Saturday, April 26, 2003 2:59 AM Subject: Re: hammer velocity =20 > Richard Moody wrote: >=20 > > YES! The hammer as it strikes the string is actually slowing > > down in theory. A major consideration of the design of the > > piano action is that the hammer must leave the impelling device, > > (jack) and continue to travel for a tiny distance free and clear, > > strike the string, rebound, and then come back in contact with > > the action mechanism which must now "catch" the hammer. >=20 > I believe there is a letoff position (just under 1mm) that is so close > that the hammer does not have a chance to start de-acceleration. I > havent gotten into all this side of things very much yet, so I am not > sure of myself here, but isnt there some sort of "left over" force = that > keeps an object in acceleration for some small period of time even tho > the origional applied force is removed ? Like a bullet coming out of = a > rifle ?? Doesnt that meet its maximum acceleration some few = milliseconds > after the explosion of the shell ? There won't be any "left over" force directly related to the downward = push of the keystick driving the hammer forward after letoff. Relative = to that, the hammer would indeed start decelerating (and hence slowing) = because of friction. As soon as the driving force is removed, = acceleration stops. A separate force is required for any other = acceleration (like friction accelerating the hammer in the opposite = direction, or decelerating if you prefer). Now like you point out, there = may be some other additional force acting upon the hammer in that last 1 = mm of travel like the hammer shank springing back. Although, in an = upright, because of the mass and hence inertia of the hammer compared to = the hammer butt, I would think most of the effect of any = straightening-out the hammer shank does would more greatly decelerate = the butt. But of course, not so on a grand. Don't know about bullets and rifles. Too dangerous. > > The only aspect of the travel of the hammer the pianist can > > control is its velocity. There might be an argument about this in > > physics because of the difference between velocity and > > acceleration. >=20 > I am sure you are right here.... (about the argument part) I have read > through 8 or 9 articles by those who have done the only readily > available real science on the subject matter and they dont draw any = hard > conclusions. Most say that things seem to point in the direction you > mention, but the door seems held open and there are others who have > their foot through that door. The physchology of our perceptions gets > into play here as well, along with what is heard and coincidently = felt. > Physics experiements have a hard time avoiding isolating too much in > order to afford an appropriate resolution for what they are trying to > look at, and in effect influence that which they are viewing. We must > never discount the reported experiences of the pianists in all this > either. The idea is to find the explaination as to why they experience > what they do. >=20 > -- > Richard Brekne > RPT, N.P.T.F. > UiB, Bergen, Norway > mailto:rbrekne@broadpark.no > http://home.broadpark.no/~rbrekne/ricmain.html >=20 >=20 > _______________________________________________ > pianotech list info: https://www.moypiano.com/resources/#archives ---------------------- multipart/alternative attachment An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/pianotech.php/attachments/56/88/40/12/attachment.htm ---------------------- multipart/alternative attachment--
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