What is the variable A in the derivation for centre of percussion?

[MathewsMD]

My original question was answered, but I would just like some clarification regarding one concept. In the derivation for the centre of percussion in this link (http://en.wikipedia.org/wiki/Center_of_percussion), what exactly is the variable A? How can it be determined (theoretically and/or experimentally)?

 

[A.T.]

In the derivation for the centre of percussion in this link (http://en.wikipedia.org/wiki/Center_of_percussion), what exactly is the variable A?

As the article says, distance from pivot to center of mass.

 

[MathewsMD]

As the article says, distance from pivot to center of mass.

Ahh thank you. For some reason I just could not see it.

At the bottom of that section, it states: "This is also the center of oscillation of a physical pendulum of the same mass M, hung at the pivot point. (The center of oscillation is the position of the mass of a simple pendulum that has the same period as the physical pendulum.)[2]"

Does the article prove this at all? Maybe I'm missing something here, but is that statement an easily seen corollary? I can show it is true for single examples, but is there a proof for the general case?