PSN-L Email List Message

Subject: Re: pendulum similar to the one mentioned
From: tchannel1@............
Date: Thu, 27 Mar 2008 12:46:36 -0600

One follow up question:

I see only one different, in this configuration, and my "Nearly Balanced" 
That is the length of the pendulum above the pivot.  On mine, it was 36", 
which is equal to that below the pivot, and the top mass was far from the 

This new configuration, moves the top mass as close to the pivot as 
possible, and I guess one could say the mass below the pivot would be as 
long a possible.
The pendulum, I guess, would be nearly balanced, but the center of gravity? 
would be as closer to the pivot?  Is This correct?

I can try this on my "Nearly Balanced"


----- Original Message ----- 
From: "Randall Peters" 
Sent: Thursday, March 27, 2008 12:06 PM
Subject: pendulum similar to the one mentioned

> Ted,
>     I built a pendulum that is similar to the one that has been
> simulated, except that it was configured to optimize sensitivity at a
> period of about 4 s (to study microseisms).  It is described at the
> following site by the paper titled "Compound pendulum to monitor
> hurricanes and tropical storms"::
> To convert the instrument shown in Fig. 1, the lower (lead) mass would
> be discarded, and the upper (lead) mass would be lowered nearly all the
> way possible (just above the axis, after which the upper tube would be
> sawed off just above the mass).


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