Inertia, was "Grand Touch"

[Cy Shuster]

Cars on a road course have to quickly change direction.  Viewed from above, 
they pivot around their centers as they turn left and right.  When the 
five-mile-an-hour bumper law was passed around 1976, it greatly reduced the 
cornering ability of many cars, especially the MG.  Hanging big weights at 
the extreme ends of the car, it made it much harder to change direction. 
Think of the spinning ice skater with arms in vs. arms out.  I believe it's 
called "polar moment of inertia", and I'll bet Dr. Birkett has it all 
spelled out in his PDF.

--Cy--
shusterpiano.com

----- Original Message ----- 
From: "William R. Monroe" <pianotech at a440piano.net>
To: "Pianotech List" <pianotech at ptg.org>
Sent: Wednesday, July 12, 2006 7:00 AM
Subject: Re: Inertia, was "Grand Touch"


> Vladan,
>
> I don't have my book handy, is this the formula for tangential MOI, or
> linear?
>
> I'm assuming tangential.
>
> Also, I would question your results (in a friendly way).  I would think 
> you
> would be taking the mass reading for the formula at the front of the key, 
> as
> you would take FW.  Thus, Mass would be mass of the keystick, not mass of
> the individual lead.  In this case, regardless how much mass you use 
> (more,
> near the balance hole, or less near the front), the Mass as measured at 
> the
> front of the key is going to be the same, thus, equivalent inertia at the
> front of the key.
>
> Comments?
>
> William R. Monroe