On Wed, 25 Feb 2004 00:48:06 +0100, "Tim Nikias v2.0" <tim.nikias (@)
nolights.de> wrote:

>[...]
>Even when a particle lies motionless on a
>surface, gravity will pull it down, adding energy (which is always stored as
                                     ^^^^^^^^^^^^^
Gravity doesn't add energy to something.
Do you mean the conversion between 'potential energy' and 'kinetic
energy'?

>a velocity vector) which will lead it to oscillate on the surface, even
>though it visibly doesn't move a bit (unless with a microscope).

No. 
Don't mistake your model/imagination for the real world.
There's nothing that causes anything to oscillate.

>Now, what I want to do is to simplify the model when the particle starts to
>oscillate:

No, you don't want to simplify your model, you want to add some
complexity to avoid 'oscillations' that don't happen in real world.

>instead of oscillating, I slide the particle along the surface -
>if possible. If a particle lies on the y-plane and its just y-velocity from
>gravitation, there's no movement at all. But when there is some x-velocity,
>it will slide along the x-axis.

>Friction and dampening is left out for simplicities sake, 
>its a particle system and, IMHO, doesn't need physical
>calculations like friction and dampening to slowly stop a particle from
>sliding along a surface.

Sorry to disappoint you, but without friction and dampening (energy
dissipation) you'll have to live with those oscillations. 

>Now, with those assumptions for my particle system, I want a very simple
>approach to calculate how much slower a particle would get when moving
>uphill, that's all I was asking for.

It has yet been posted. All you need is the conservation of energy,

0.5 * m * sqr(v) + m * g * h = const (as you don't like friction &
dampening).
 
> I've stated that I don't need friction, [...]

No. You have stated that you need, but don't want friction, dampening,
...
May be I'm completely mistaken, please tell me what you would expect
for your particle system for just one particle in this case.

BTW You are aware of the possible problems of
- modelling using discrete time series,
- limited accuracy of calculations, 
?


-- 
Andreas

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