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<DIV><FONT face=Arial size=2>Hi Ed:</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>All that would be left is the =
"sluggishness" of the
parts,<EM> i.e</EM>. the tendency of the key not to want to move =
and not to
want to <EM>stop</EM> moving. The force required would be =
proportional to
how quickly you try to change the speed of the key. Incidentally, =
if you
totally balance out the weight of the hammer, the key won't come back up =
to its
starting position.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Think about an ordinary playground
teeter-totter. With no one in either seat, it is easy to move it =
around
and it stays where you put it. Now put a fat kid on either end =
(both the
same weight). It's still balanced and stays where you put it, but =
it is
much more difficult to start and stop it. The fatter the kids, the =
more
moment of inertia the system has. To start one kid upward quickly =
takes a
big heave. Then if you want to stop him it is also difficult; in =
fact, he
may actually lift you off the ground if he has enough energy at that
point. The feel would not be the same at all for an empty
teeter-totter.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Note that since the system is balanced, =
any
disturbing force can tip the teeter-totter, no matter how small =
(neglecting
friction). I can drop a small brick in one kids lap and start =
the
lever turning and it will accelerate faster and faster until he strikes =
the
ground. The key concept to realize is that the teeter-totter will
accelerate at a greater rate if I drop the same brick onto it when =
it's
empty than with two fat kids sitting in it. If I put two 500-lb. =
slabs of
concrete in each seat, the brick will accelerate them even less, though =
the
system is still balanced. </FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Don A. Gilmore<BR>Mechanical =
Engineer<BR>Kansas
City</FONT></DIV>
<BLOCKQUOTE dir=ltr
style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; =
BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: =
black"><B>From:</B>
<A title=ed440@mindspring.com =
href="mailto:ed440@mindspring.com">Ed Sutton</A>
</DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=caut@ptg.org
href="mailto:caut@ptg.org">College and University Technicians</A> =
</DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Monday, January 05, 2004 =
5:51
PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> What does the moi feel =
like?</DIV>
<DIV><FONT face=Arial size=2></FONT><BR></DIV>
<DIV><FONT face=Arial size=2>Dear Physicists of the =
List-</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Please comment on this =
thought:</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>When I press the piano key, the =
resistance to
movement I feel consists of three elements</FONT></DIV>
<DIV><FONT face=Arial size=2>1) Friction</FONT></DIV>
<DIV><FONT face=Arial size=2>2) The pull of gravity on the hammer =
and wippen,
partly counterbalanced by the pull of gravity on the =
keyfront.</FONT></DIV>
<DIV><FONT face=Arial size=2>3) The combined MOI's of the various =
moving
parts.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Therefore, if I can </FONT></DIV>
<DIV><FONT face=Arial size=2>1) reduce the friction to zero, and =
</FONT></DIV>
<DIV><FONT face=Arial size=2>2) use a wippen assist spring to =
produce a
balance weight of zero, the only resistance left would be =
</FONT></DIV>
<DIV><FONT face=Arial size=2>3) the combined MOI's of the key, =
wippen and
hammer. </FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>What I would feel then, in various =
key strokes,
would be whatever it is we are talking about. </FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Could I make or buy a gauge to =
measure
this?</FONT> </DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Does this line of thought seem useful =
in
understanding the situation?</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>For example, has anyone felt a key =
such as I
describe?</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Ed =
Sutton</FONT></DIV></BLOCKQUOTE></BODY></HTML>