PSN-L Email List Message

Subject: Re: science fair seis
From: "J. D. Cooley" cooleyj@....................
Date: Tue, 17 Apr 2001 19:04:13 -0700

This was EXCELLENT.  Thank you very much for this insight into what a
science fair judge is looking for.  Although my children are already grown,
I will give this to the  parents of my 7-year-old grandson, so that it can
be used as a guide!

Once again, thank you,

"JD" Cooley

At 03:36 PM 4/17/01 , Sean-Thomas Morrissey wrote:
>Hi seismometer Mom,
>I agree with Erich's comments.
>I have often been a judge for the local science fair, and have seen
>many versions of paper mache' volcanos (models aka "Close Encounters"
>providing no science), earthquake "predictions" based on caterpillars 
>(a result of selective hearsay and coincidence), and wooden seismometers 
>crushed by an ever increasing mass of bricks in an attempt to get 
>My usual approach to a fair exhibit is to first try to find an explicit
>statement of the scientific question of the display. This is the
>"how do we know ...." or "Why does" or  some hypothesis that can
>be demonstrated by a simple experiment (beans grow faster in an 
>electric field). If there is no question or hypothesis, there can be
>no scientific test or demonstration of a principle, and therefore,
>no "results".  For a seismograph or seismometer display, the question 
>is "how do we detect the faint ground movement of distant earthquakes".
>Then I look for some experiment to evaluate the question. Usually
>the answer is known by science, so showing how we know it is 
>demonstrated by some replication of the physical experiment or, 
>in the case of like math or astronomy, a large poster detailing the 
>logical steps that lead to the conclusion is presented (some have
>that ring of verbatim Brittanica, especially when a gross error in
>copying is evident).
>So for the "how do we know" science display, a demonstration of the 
>core physics is usually presented within the amateur limitations of
>the student. For a seismometer/seismograph, recording the relative 
>motion of a suspended inertial mass with respect to the moving ground 
>is the key concept. Amplifying the miniscule motion (0.001mm) 
>from a distant quake is more advanced. A comprehensive background
>poster of earth/core wave propagation is easy to assemble. And a
>poster with good graphics can detail all the concepts, including
>wave propagation and quake location without having to build a 
>seismograph. A demo on a map on the table of triangulation of the 
>epicenter location from station S-P travel times represented by 
>using marked tapes is a nice interactive display.
>A fatal misconception is that some hardware something must be built
>that should prove or demonstrate the point, (often overlooking the
>practical alternative of borrowing a professional instrument and
>then carefully labeling the key components.) This construction then 
>becomes the prime effort of the display even though the student 
>(parent) has not grasped the physics or science involved.  Then the 
>display becomes an exhibit of the construction skills of the student 
>(parent), which often blindly copy some article. 
>I have seen beautiful all-wood Lehman type sensors but made with 
>brass cabinet hinges and a brick for a mass with a pencil attached 
>that writes on a tablet placed under the front side. The student 
>got high marks because of the instructions: "slowly slide tablet 
>out while shaking the table"; the principle of the inertial mass 
>was proven, as was the registration of a the waveform passing with
>time: ie "results". The display even noted that the table shaking
>was about intensity MM-X, and referred it to a graphic about intensity.
>However, often the entire point is missed and the "results" are
>faked; ie."simulated". One seismometer display had a lead pipe hanging 
>on a spring, with the attached pencil writing on a paper cylinder resting
>on an open clock face (sort of turned by the minute hand). There was a
>nice tracing of a teleseism, carefully labeled to agree with an
>attached news clipping. But no current demonstration of how the
>data was or could be made. (Fair judges often converge on a display
>that challenges their ability to "make it work", and sometimes make
>adjustments or add something that does make it work).
>The value of an exhibit is proportional to the time devoted to it.
>A good high school project will take about a year, with the last
>half devoted to building whatever and trying to make it work. 
>Then, in the case of a sensitive seismograph (with a magnification of
>at least 1000,) you might have to wait a month for a significantly
>large earthquake to record on it.
>But I have never seen any seismograph displays involving even rudimentary
>electronics (moving coil/magnet and amplifier), but this is the
>midwest rather than California, and although electricity is a 
>high school subject, the practical usefulness of it remains elusive.
>And a final note: "quick" and "easy" have nothing to do with science.
>Sean-Thomas Morrissey
>St. Louis University.
>PS: there is a design for a hardware store seismometer using modern
>electronics that is neither quick (could be done in a devoted month)
>nor easy (those darn electronics parts) described at:
>stmseis.html" The STM-8 Leaf Spring Seismometer: Photos and Report
>stmfigs.html" The STM-8 Seis: Figures, Schematics, Drawings
>stmquakes.html" The STM-8 Seis: Recent Quakes, Data
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Larry Cochrane <cochrane@..............>