Message-Id: <3.0.32.19990318060012.008c6a30@netmail.home.com>
Date: Thu, 18 Mar 1999 06:00:13 -0700
To: pinhole@exploratorium.edu
From: The Lahrs <JohnJan@lahr.org>
Subject: mouse trap report
Lou Morton wrote:
"A fellow teacher of mine says he recalls in college a science teacher
telling him of a fabulous science demo on nuclear chain reactions: A
large number of mouse traps..."
The mouse trap chain reaction demo was discussed on the
tap-l list last Fall. I saved this message from Jeff Rudd,
which would probably help if you want to try it.
John
>Return-Path: <owner-tap-l@listserv.appstate.edu>
>Date: Mon, 28 Sep 1998 13:15:02 -0700
>From: Jeff Rudd <rudd@SFU.CA>
>To: tap-l@listserv.appstate.edu
>Subject: mouse trap report
>Reply-To: tap-l@listserv.appstate.edu
>Sender: owner-tap-l@listserv.appstate.edu
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>
>We did the mouse trap chain reaction demo this morning. Many thanks to
>everyone for all the advice of a few weeks ago.
>
>For those interested here is my report:
>1) Mouse traps
>There are 3 types of traps available in hardware stores here:
>Pro-catch (Taiwan) - useless, difficult to set and very hair trigger
>Catchmaster (Atlantic Paste & Glue Company) - not bad
>Victor - I found these the easiest to set reliably
>
>One of the great things about this job is the look on the saleswomen's
>face when walking up to the counter with 50 mousetraps.
>
>2) loose traps
>I started by setting 42 traps loose on the table, 2 ping pong balls per
>trap, in a large plexiglas box borrowed from another demo. This worked
>well. I am not sure how many traps were set off by ping pong balls and
>how many by flying traps. I can imagine that the traps might go off
>without any balls at all - but I'm not going to try it.
>
>3) fixed traps
>Our faculty member was determined to do the demo of dropping a ball
>without a box and showing that there is no chain reaction. This requires
>having the traps fixed. I screwed the traps to a piece of 1/2 inch
>plywood in a 6 wide by 7 long array, spaced as closely together as
>possible allowing a bit of clearance for the ping pong balls. This
>choice was determined by the size of the box. I started by screwing the
>traps down tight. Setting off one trap then caused all the other traps
>to go off. There seems to be two reasons for this - coupling through the
>plywood, and the set wire hitting an adjacent trap and setting it off.
>Loosening the screws so the traps were free enough to be lifted 3/16
>inch or so solved the coupling through the board problem. Placing 3/4
>inch high strips of wood between the rows solved the setting wire
>problem. With these modifications it was possible to trip one trap
>without any others going off. I get the impression from the replies on
>the list that others haven't experienced these problems.
>
>4) doing the demo
>I set all the traps outside the lecture hall half an hour before the
>lecture, then carried the board in and placed the balls on the traps in
>the 10 minutes we have for setup between classes. Setting the traps
>wasn't too bad although the hands were shaking a bit.
>
>The prof started with no box. He threw a single ping pong ball onto the
>board. This set off 3 traps, 7 ping pong balls went flying. Then he
>carefully placed the box on top, tossed in a ball and the chain reaction
>took place. All but 2 of the remaining traps went off. This is as close
>to perfect as can be expected.
>
>5) comments
>The set up needs to be improved - maybe space the traps a bit farther
>apart, build a box with hinged sides and so on. Although it worked well
>I don't really like the demo. The return on the investment is too low.
>It worked well this time but I can see that it could be very unreliable.
>
>Again, thanks for the advice.
>
>
>Jeff Rudd
>Physics Dept
>Simon Fraser University
>Burnaby, BC, Canada
>
>
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