Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!ncar!tank!eecae!abaa!esker
From: esker@abaa.uucp (Lawrence Esker)
Newsgroups: comp.sys.amiga
Subject: Re: Amiga Survives 7.0 Earthquake
Message-ID: <4282@abaa.UUCP>
Date: 23 Oct 89 15:56:27 GMT
References: <23238@cup.portal.com>
Reply-To: esker@abaa.UUCP (Lawrence Esker)
Organization: Allen Bradley
Lines: 67

In article <23238@cup.portal.com> thad@cup.portal.com (Thad P Floryan) writes:
>
>                    Amiga Survives 7.0 Earthquake
>
>Makes a nice headline, eh?  :-)

Yes it does.  Where's C='s ad company?

>This bring up an interesting technical question: what is the equivalent ``G''
>force experienced by equipment during an earthquake?  Is this question even
>relevant, or should the horizontal- and vertical-axis oscillations be taken
>into consideration?  I ask because (typical) specs for disk drives state:
>
>How do those shock and vibration specs relate to the "real world"?

I have always wondered myself.  I work for a company that does vibration and
shock testing of all products before they are released.  I've always wondered
if the minimum levels we test to is resonable or overkill for the real world.

>The stands upon which all my systems are operated are highly modified
>"Tiffany" stands (Tiffany in this sense is NOT the jewelry company but,
>instead, a mfr of extremely heavy-duty typewriter stands) whose bases are
>loaded (my mods) with heavy wood platforms each supporting a UPS and other
>peripherals.  I think it unlikely ANYTHING could tip these over.  Not one
>moved more than 2 inches, yet a 2000+ lb. bookcase moved 4 inches from one
>wall, and all my (full) filing cabinets danced-out 6 inches from another
>wall.  I don't even want to discuss the other bookcases that collaped
>and/or fell, and the other messes.

The shape of the object has more to do with it than the weight:

    +------+    Falls over
    |      |
    |      |
    |      |        +--------+    Wobbles
    |      |        |        |
    |      |        |        |        +--------------+    Doesn't move
    |      |        |        |        |              |
    +------+        +--------+        +--------------+

A force vector forms at the point of the object's center of gravity.  The
weight force pointing down combines with the earthquake force moving sideways.
If the combined vector points from the center of gravity to a place outside
of the base of the box, the box will move.

                          +--->  Earthquake
                          |\
                          | \
                          |  \
                  Weight  v   x  Combined

Of coarse, this was the simplistic laymens description.  Didn't feel like
writing a book.

>Which leaves me, in conclusion, asking how other people's systems fared, and
>what, if anything, can be done to prevent system damage with forces of this,
>or greater, magnitude.

Several colleages were in the area at the time for a seminar.  I should have
been there but got sent to Ft. Lauderdale, FL to fix a customer fire.  They
had lots to talk about when we all got back.

>Thad Floryan [ thad@cup.portal.com (OR) ..!sun!portal!cup.portal.com!thad ]
--
---------- Lawrence W. Esker ----------  Modern Amish: Thou shalt not need any
                                         computer that is not IBM compatible.
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