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Re: Models Computational Physics



I do think there is a lot for students to learn by modeling some aspect of
physics. The project I have successfully used is the motion of charged
particles. The project is to program (from scratch using True Basic or
Pascal) an animation that shows the motion of three charged particles (
constrained to act in 2 dimensions) where the mass, charge, and initial
position of the particles are adjustable (could also add initial velocity).


While the students don't necessarily have a strong grasp of the physics at
this point, they do know the basics--i.e. like charges should repel and
unlike attract, basic kinematics. They have enough of this kind of feeling
to test their programs. The program itself is surprisingly short, but DOES
require that they break the problem down into components to deal with the
vector addition of the forces, and work over short time intervals such that
the forces can be taken as constant for that period. They must deal with
working out the computational details to assure the correct direction of
the 1-dimensional force components, then compute the acceleration,
velocity, and position components. Finally they must deal with the
boundary conditions (screen edges and more importantly--close encounters).
For the close encounters they must decide how to deal with very small (or
zero) separations of charges. This can be simple--constrain the separation
distance to be greater than some fixed value, or complex--let the particles
collide elastically.

The overall process of breaking down the problem to its bare essentials is,
I believe, a valuable one for students. The final product is seemingly
quite complex, but through the programming process is clearly composed of
simple applications of fundamental concepts in a ordered, logical way.


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Richard W. Tarara
Department of Chemistry & Physics Free Physics & Energy Instructional
Software
Saint Mary's College available at:
Notre Dame, IN 46556
219-284-4664 http://estel.uindy.edu/aapt/rickt/software/
rtarara@saintmarys.edu
http://www-hpcc.astro.washington.edu/mirrors/tarara/
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