Magic (splitting hair) lines

[william ballard]

On Jul 19, 2006, at 8:47 PM, John Delacour wrote:
> It is in this state that a) all the static friction needs to be  
> overcome and b) the normal force is at its greatest. Once things  
> are moving, at whatever velocity -- and even the maximum velocity  
> in this case is low -- then we are dealing with kinetic friction.

Don't forget as well that on top of the normal force (essentially  
gravitational) there is additionally the force of inertia, as the  
parts resist whatever amount of acceleration the pianist is trying to  
push them into. As the finger/hand/arm and the action parts reach a  
consensus velocity, the acceleration all but tapers off as will the  
force of inertial resistance. But the force of inertia is also  
highest at the start  of the stroke

Mr. Bill