From: SFPhysics@aol.com
Date: Wed Feb 07 2001 - 12:55:16 PST
From: SFPhysics@aol.com Message-ID: <16.888211b.27b31034@aol.com> Date: Wed, 7 Feb 2001 15:55:16 EST Subject: Re: Pasta/Toothpick Bridges
> Hey physics teachers or anyone who knows about scaling-
> Has anyone heard of a project in which students build bridges out of pasta
> and glue? Sounds crazy, but I heard of physics classes doing this. The
> project provides students with a way to understand the cross sectional area
> to volume ratio (strength/weight ratio).
> Thank you!
> Coco Ballantyne
> Eastside College Preparatory School
> East Palo Alto
>>
The Bridge Project is a great way to have the students do research and build
a demonstration of their resolution of forces model. I had my students do a
term paper on bridges then make a model of their own design. Originally
these were done with various types of pastas from angelhair to spaghetti to
linguini. The San Francisco high school where I was teaching had a mouse and
rat problem so bridges left overnight got eaten. We switched to toothpicks
and used hot glue guns. The hot glue allows a joint to be made in minutes
whereas the glue, Elmers, takes hours to dry. The students loved the end of
the project when the bridges were destructively tested. It was not uncommon
for a bridge to hold 10,000 times its own weight. The almost instantaneous
collapse of a bridge is a great demonstration of elastic limit. We used a $6
dollar dial gauge from Harbor Freight Tools to show bridge deformation as
mass was placed on the structure. If you are good with construction you can
make a standard "gap" with wood blocks that the bridge must span and have a
set of rules the students must use. e.g. No gluing pasta/toothpicks into a
solid block as they may only have glue applied within 10 mm of the ends.
I lifted the project and expanded the idea from my son's 8th grade science
teacher at Sinaloa Middle School in Novato, California. Where she got it I
do not know but it sounded like an Exploratorium snack. I may still have
some of the lesson plans and handouts I did for my students. List the
complete address of your school and I'll send them to you.
Al Sefl
Retired but still teaching Physics...........
This archive was generated by hypermail 2b29 : Tue Oct 16 2001 - 12:22:15 PDT