<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD> <META http-equiv=Content-Type content="text/html; = charset=iso-8859-1"> <META content="MSHTML 6.00.2800.1106" name=GENERATOR> <STYLE></STYLE> </HEAD> <BODY> <DIV><FONT color=#008000>I may not know much about pianos, but I know = a little about physics! Comments below:</FONT></DIV> <DIV><FONT color=#008000></FONT> </DIV> <DIV><FONT color=#008000>Terry Farrell</FONT></DIV> <DIV> <SPAN id=__#Ath#SignaturePos__></SPAN> </DIV> <DIV>----- Original Message ----- <DIV>From: "Richard Brekne" <<A href="mailto:Richard.Brekne@grieg.uib.no">Richard.Brekne@grieg.uib.no</= A>></DIV> <DIV>To: "Pianotech" <<A href="mailto:pianotech@ptg.org">pianotech@ptg.org</A>></DIV> <DIV>Sent: Saturday, April 26, 2003 2:59 AM</DIV> <DIV>Subject: Re: hammer velocity</DIV></DIV> <DIV> <BR>> Richard Moody wrote:<BR>> <BR>> > YES!  The = hammer as it strikes the string is actually slowing<BR>> > down in theory.    A major consideration of the design of = the<BR>> > piano action is that the hammer must leave the  impelling device,<BR>> > (jack) and continue to travel for a tiny distance = free and clear,<BR>> >  strike the string, rebound, and then come back = in contact with<BR>> > the action mechanism which must now "catch" = the hammer.<BR>> <BR>> I believe there is a letoff position (just = under 1mm) that is so close<BR>> that the hammer does not have a chance to start = de-acceleration. I<BR>> havent gotten into all this side of things = very much yet, so I am not<BR>> sure of myself here, but isnt there some sort = of "left over" force that<BR>> keeps an object in acceleration for some small = period of time even tho<BR>> the origional applied force is removed ?  = Like a bullet coming out of a<BR>> rifle ?? Doesnt that meet its maximum acceleration some few milliseconds<BR>> after the explosion of the = shell ?</DIV> <DIV> </DIV> <DIV><FONT color=#008000>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.</FONT></DIV> <DIV><FONT color=#008000></FONT> </DIV> <DIV><FONT color=#008000>Don't know about bullets and rifles. Too dangerous.</FONT><BR><BR>> >     The only = aspect of the travel of the hammer the pianist can<BR>> > control is its velocity.  There might be an argument about this in<BR>> > = physics because of the difference between velocity and<BR>> > acceleration.<BR>> <BR>> I am sure you are right here.... (about = the argument part) I have read<BR>> through 8 or 9 articles by those who = have done the only readily<BR>> available real science on the subject = matter and they dont draw any hard<BR>> conclusions. Most say that things seem = to point in the direction you<BR>> mention, but the door seems held open and = there are others who have<BR>> their foot through that door. The physchology of = our perceptions gets<BR>> into play here as well, along with what is = heard and coincidently felt.<BR>> Physics experiements have a hard time = avoiding isolating too much in<BR>> order to afford an appropriate resolution = for what they are trying to<BR>> look at, and in effect influence that which = they are viewing. We must<BR>> never discount the reported experiences of the = pianists in all this<BR>> either. The idea is to find the explaination as to = why they experience<BR>> what they do.<BR>> <BR>> --<BR>> Richard Brekne<BR>> RPT, N.P.T.F.<BR>> UiB, Bergen, Norway<BR>> <A href="mailto:rbrekne@broadpark.no">mailto:rbrekne@broadpark.no</A><BR>&= gt; <A href="http://home.broadpark.no/~rbrekne/ricmain.html">http://home.broad= park.no/~rbrekne/ricmain.html</A><BR>> <BR>> <BR>> = _______________________________________________<BR>> pianotech list info: <A href="https://www.moypiano.com/resources/#archives">http://www.ptg.org= /mailman/listinfo/pianotech</A></DIV></BODY></HTML>