Re: [Phys-l] Interactive Physics Simulations

[John Mallinckrodt <ajm@csupomona.edu>]

On Oct 9, 2006, at 12:02 PM, Cindy Schwarz wrote:

> you definitely CAN get things to "stick" in IP - I have done it in my
> IP Workbook (which I also now have to boot into windows to run on my
> macbook pro) - but rumor has it from the president of the company
> that now has IP that they are indeed going to do an OSX version.
>
>
> Anyway what you need to do is change the accuracy - (hence the speed)
> - make the integration type different - time step smaller etc. cant
> look at the program right now but its definitely "doable"

Cindy,

I suspect what you are thinking about is the case of a head on,  
totally inelastic collision in a gravity free environment.  In that  
very limited case, one doesn't need the objects to "stick" in order  
to remain (almost) in contact.  It is also true in this case that one  
needs to tweak the accuracy and integration methods to obtain a truly  
inelastic collision.  However, if the collision isn't precisely head  
on, then the angular momentum of the system will cause the two  
objects to separate and if, as in this case, one of the objects is  
suspended while the other is not, then gravity will cause them to  
separate.  Unless things have changed very recently, "sticking" is  
not, unfortunately (and somewhat mystifyingly), one of the options in  
IP.

I'm pleased to hear that the publisher is going to do an OSX version,  
but trepid to hear the likely upgrade charge.

John Mallinckrodt

Professor of Physics, Cal Poly Pomona
<http://www.csupomona.edu/~ajm>

and

Lead Guitarist, Out-Laws of Physics
<http://outlawsofphysics.com>