## PSN-L Email List Message

Subject: Re: Did I get 12 second period ?
From: "Geoffrey" gmvoeth@...........
Date: Sun, 24 May 2009 22:48:29 -0700

```It Seems To Me your floor was not level to begin with ?
You most probably needed an angle of 1 degree or less
from level ?
I figure a little over 2 degrees for only 5 seconds
using trig to figure the effect on the acceleration
of gravity.
P=2PiSQR(L/g)
P = period in seconds
Pi = 3.121(whatever)
SQR = SQUARE ROOT OF()
L = length of pendulum in inches
g = gravity in inches per (second squared)
g' = SINE or COSINE of the anglular displacement from zero g

If you fix L
at current gravity
you change angle according to
SINE or COSINE
like g sin(angle) relative to horizontal
or vertical.
At vertical you got full g
but at horizontal or inverted its zero.
Sort of vectored by a lever arm.
A spring with a linear constant acts
just like a pendulum.
If it takes 10 inches to get one second on a
pendulum it also takes ten inches of extension
of a spring to get one second.
Or so it seems to me.
In Physics class we used this frictionless
puck floating on a rail at different angles
to show how it could affect the acceleration.
Frictionless on a cushion of air.

----- Original Message -----
From: "Jón Frímann"
To: "PSN-Postlist"
Sent: Sunday, May 24, 2009 1:35 PM
Subject: Did I get 12 second period ?

Hi all

I did one little change to my lehman seismometer. I did rase the front
of the seismomter up from where it was. This appears to have incresed
it's period to about 12 seconds.

Here is are pictures of what I did.
http://www.jonfr.com/myndir/v/geology/lehman/p5240001.jpg.html

I can send psn file to anyone how wants.

Regards.
--
Jón Frímann

http://www.jonfr.com

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