PSN-L Email List Message

Subject: Re: Mass deflection weight test
From: John Lahr johnjan@........
Date: Thu, 01 Nov 2007 11:46:23 -0700

Hi Meredith,

There are two issues involved.  One is the absolute deflection due to 
adding a weight and the other is the electronic response, once some 
motion sensor has been applied.

The absolute deflection when a weight is added is equivalent to 
changing the acceleration of gravity, which is also equivalent to 
applying a constant acceleration.  The deflection will be a function 
of the free period; the greater the period the greater the 
deflection.  This assumes that there is no friction at the hinge.  To 
test various hinges, one would want a very long period 
pendulum.  Then a very small weight should cause a known, specific 
deflection.  If there is less deflection, then the cause must be friction.

Usually the term sensitivity relates to the electronic output per 
unit of motion, measured as displacement or velocity or acceleration 
at a given period.


At 08:26 AM 11/1/2007, you wrote:
>Hi John,
>OK on the correction.  Per your web site, that particular "item" had 
>more to it, than
>what we've texted here of course.  I used a mass head reference 
>object and eyeballed it
>when putting the paper size I used down on the mass.  Suspect one 
>might see the
>deflection of the AS-1 mass also if they "look" for it as described, 
>but without
>dampening or the coil hooked up; in free mass response.  Its rather tough to
>gauge any verticals sensitivity without further completing the whole 
>are much more difficult to adjust and maintain overall.
>On 10/31/07, John Lahr <johnjan@........> wrote:
>The paper I use is 2 cm by 1 cm, with an estimated weight of 0.0338
>gm.  I don't think the
>deflection of the boom could be seen with the eye, but I haven't tried.


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