Key Leads and Inertia

[Bill Ballard]

At 7:18 AM -0400 4/25/03, Farrell wrote:
>  > 3. Exceeding 980/sec^2 just means you are not getting any more <<help>> as
>>  it were from the force that is gravity. But this isnt the same as saying
>>  that doing so somehow creates an increase in resistance to
>>  acceleration....yes ?? Its not like gravity has a kind of reverse gear
>>  affect here.
>
>No, gravity does not change, it is an acceleration force that 
>is consistent. The pianist is the one that is applying an additional 
>acceleration force. If the finger force is less than that of 
>gravity, adding lead to the key will decrease the amount of force 
>required to push the key down at some acceleration rate less than 
>that of gravity. If the finger force is greater than that of 
>gravity, adding lead to the key will increase the amount of force 
>required to push the key down at some acceleration rate greater than 
>that of gravity.

Force of Gravitational Attraction is a function of the two masses in 
question (here, the masses of the action parts as their moments of 
inertia are modulation by the levers in the system, combined with the 
mass of the earth). Fly this piano to the moon, and the balance 
weight would change (being based on weight). The system inertia being 
based on mass, would remain the same.

Also unchanged would be the fact that inertia would be encountered 
only when the direction or speed of the parts change, but both 
friction and gravitational attraction are forces to be encountered 
throughout the motion of parts.

At 12:23 AM +0200 4/26/03, Isaac OLEG wrote:
>I guess that what disturb the most the pianist is the initial breaking
>of the inertia, once the key is moving he use the inertia and it's
>kinetic energy.

Yup, the energy to overcome inertia is a capital (start-up) 
investment, and that to overcome gravity and friction are operating 
expenses.

Bill Ballard RPT
NH Chapter, P.T.G.

"Woh"
     ...........Keanu Reeves in "The Matrix"
+++++++++++++++++++++