Re: Big Ben...

[Herb Schulz <herbs@interaccess.com>]

> I suspect they are adjusting the center of mass of the physical
> pendulum...I doubt if it is an ideal pendulum in the sense that all the
> mass is in  the bob.  Thus changing the center of mass changes the
> effective length and hence the period.

Howdy,

I think we're about to get onto shaky ground here.  A Physical Pendulum
does NOT act as though it is a Simple Pendulum that has a length equal to
the distance from the pivot to the Center of Mass of the Physical Pendulum.
The length of the equivalent Simple Pendulum is the Radius of Gyration of
the Physical Pendulum measured about the given pivot, sqrt(I/M).  Let's NOT
talk about the position of the CM to avoid confusion.

Good Luck,

Herb Schulz
(herbs@interaccess.com)