Pendulum project update

[Christopher Sawtell]

On Fri, 25 Apr 2003 03:05, Kim Rose wrote:
> I think it is wonderful to see how the Etoy system can motivate and
> promote learning in *us*!  The adults!  Look how Phil has been
> motivated to read and explore more by seeking out expert advice.
> Look how our community (thanks to Bert and others) are responding and
> adding to Phil's "knowledge base" --
> geesh, maybe we've got a tool to amplify adult learning!  (I know it
> has worked for me!)
Perhaps more a better slogan might be something along the lines of:-
"A superbly effective tool to enhance learning for people of all ages".
Without a shadow of doubt that has been the case for me. It has also given me 
the motivation to learn something of the underlying computer language.


Certainly this "Pendulum" thread has been one of the more informative and 
interesting threads I have had the priviledge to read since I have been on 
e-mail lists.

Now for the real purpose of the message. I seem to somewhat vaguely remember 
from the misty, distant past of some 45 years when I did my bit of School 
Physics that our teacher, one Dr. Watson, explained the motion of the 
pendulum using the fact that while energy can be converted from one form to 
another, it can never be destroyed. In the case of the pendulum the forms of 
energy are the Potential Energy imparted to the bob by lifting it up to the 
extremity of its swing. This is completely converted into Kinetic Energy at 
the bottom of the swing, and then totally converted back again to Potential 
Energy at the moment when the bob is stationary at the other end of the 
swing.

Therefore, if my failing memory serves me correctly, at all times:-

 mh - mv^2 = k

Solutions of the Pythagorean geometry, for which the missing square-root 
arithmetic function in the e-toy tile would be _really_, _*really*_ useful, 
are left as an exercise for the reader. :-)

Is there perchance a "Within-the-scripting-window" method of doing interations 
so that the Newtonian approximation method can be used in a way which is 
understandable to a school pupil?

It'll be interesting to see what I come up with as an implementation of the 
simulation.

> Thanks for the great exploration, and support of learning no matter
> who the learner....
> best to all,
>   -- Kim
>
> >So, I've done a little reading (Physics Made Simple, etc,) and most
> >recently consulted with a physics professor who happens to be in the
> >family. As a result, I'm fairly (if not completely) convinced that
> >creating a realistic pendulum is well beyond what 5th graders could
> >do. I'm not even sure if I'll ever be able to complete the project
> >myself.
> >I have learned a lot about pendulums, gravity, etc.
> >I realize now that my pendulum does not reflect reality because it
> >moves at a steady rate through it's swing when, in fact, a pendulum
> >accelerates in its downward motion and decelerates in its upward
> >motion.
> >In order to simulate reality I need to be able to change the rate of
> >acceleration of the heading of my pendulum. I now have a formula
> >that would accomplish this, however, it includes a square root
> >function. Is that possible in the etoy environment?

-- 
--
C. S.