Re: springs and negative gravity

> Sounds like fun! So I'm gathering you were doing a time-history,
> keeping track of location and velocity?
>

Beats me what I was trying to do but that sounds familiar. You
couldn't do it all with just position because then it would
'stop' when it crossed x=0.

A bunch of silly ideas come to mind but the most likely
is modelling a liquid surface as a grid of springs attached
together.

+------+-----+-----+---
/s /s /s /s
/ s / s / s / s
+-----+----+---+---+--
s s s s
s s s s
s s s s

Note a single strand of these could model a guitar string and
the whole mess of them could model a drum head or cymbal.
I was into sound synthesis algorithms at the time.

There are, of course, much better ways of doing these things.
I can't remember at all why positive force at low displacements
was a good idea since that would always make it oscillate,
feedback? Some kludge to try to beat some damping in the
system?

> I remember reading about negative gravity in the news recently; they
> didn't give any numbers. But increasing repellence as the square of
> distance sounds awfully extreme! I'd like to know more...

Well, its not that bad. Positive gravity needs a lotta mass and a
little distance and even then is a pretty weak force. So negative
gravity operates with lots of mass at lots of distance. Now I
have no idea if there is a singularity in the negative gravity
domain like the 'black hole' in the positive...

Bob Valentine

>
> JdL
>