Re: [Phys-l] mass and the ring down (free decay) of a pendulum

[Brian Whatcott <betwys1@sbcglobal.net>]

At 11:09 AM 6/9/2007, you wrote:
> PHYS-L, PHYSHARE, and TAP-L, people!
>
> There is a controversy among the horological community on the effect of
> pendulum mass on the steady state amplitude of an escapement driven
> clock, in particular the impulsing by the gravity arm of a Synchronome
> clock.  Theoretically for a simple pendulum clock with a decay constant
> independent of the mass, there is, obviously, no effect.  However, the
> free decay (they call it "run down") is, theoretically much effected;
> the time is proportional to the mass.  I have searched somewhat
> diligently and find no data (experimental) relating to this effect.  Do
> any of you have such?
>
> bc, frustrated.

I expect I am entirely missing bc's point.
This appears to be a question centering on mechanical Q: the ratio of
energy stored to the energy lost per cycle.
It seems like increasing the bob weight should increase Q,
But this may well increase the bob weight drag,
which should decrease Q.     Hence the decay constant of a pendulum
 should not be independent of its mass.
As to experimental data - this is the grist of engineering labs
such as this one:

<http://www.physics.odu.edu/hyde/Teaching/Fall04/Lectures/ResonanceLab.html>



Brian Whatcott    Altus OK    Eureka!