Pendulum

[Phil Firsenbaum]

I agree. I'm not interested in a frame by frame animation, because it 
wouldn't simulate the reality of a pendulum. I do want to avoid the 
trig but I'm not sure I see how I'd "weigh" the forces of gravity at 
different angles...hope I can figure it out.
Phil


On Tuesday, April 15, 2003, at 07:02 PM, Alan Kay wrote:

> What's the model behind the "movin' pictures"?
>
> The simple frame by frame animation has a very weak and almost 
> nonexistent model.
>
> But, as you've seen from our demos and the DVD documentary, even 5th 
> graders can figure out the two line script that represents an 
> excellent 2nd order differential equation of the (almost) constant 
> accelleration of gravity near the surface of the earth. This is what 
> drives a real pendulum.
>
> Now you just have to "see" how the downwards and sideways forces 
> change with the position of the pendulum and you can easily make a 
> real model of it.
>
> Enclosed is a project that has noticed that the rotational force is 
> proportional to the sine of the angle of the pendulum. But, there is a 
> nice way to bypass trig completely by directly "weighing" the forces 
> exerted by gravity at different angles ... heh heh ...
>
> Cheers,
>
> Alan
>
> --
>
> At 3:23 PM -0400 4/15/03, Brucestro at aol.com wrote:
>
> Andreas/Phil,
>
> Wouldn't another possilble approach be to create a series of pictures 
> showing all the possible positions of the pendulum and then control it 
> as one would control a cartoon/movie?? (Phil - There are examples of 
> this technique at squeakland.org under the eToys link.)? Another 
> option that comes to mind is to stack each of these pictures on top of 
> each other and move them front to back as required.? Andreas, I'm new 
> to Squeak -- would these ideas work, or am I on the wrong track?
>
> Thanks,
> Bruce Strothenke
> Teachers College Columbia University
>
>
>
> -- 
>
> <PendulumTaTum.001.pr>
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