Re: [Phys-l] Interactive Physics Simulations

[John Mallinckrodt <ajm@csupomona.edu>]

Ron Curtin wrote:

> For those of you who use the IP simulation program:  Some of my  
> students are trying to build a simulation of a rotation problem and  
> having a
> problem.  The problem involves a vertical long rod, pivoted on the  
> upper end.  The rod swings down and its lower end collides with wad  
> of putty. It's supposed to stick to the small putty wad, and then  
> the rod and putty swing up a bit and then temporarily stop.  We  
> can't get the putty
> and the rod to stick together.  I've tried setting the elasticity  
> of both at 0.  Does anyone out there know how to make the two  
> objects collide and stick together? Thanks.

Ron,

As you probably understand, "zero elasticity" is not the same thing  
as "sticky."  One possible solution is to make the long rod using the  
polygon tool and build a very small "cup" at the bottom that will  
hold the ball after the collision.  Another more complicated  
possibility would be to design a short range user designed attractive  
force between charged objects and then attach small charges to the  
rod and the ball near the point of contact.

BTW, I used to work a LOT with IP and I still consider it to have  
BEEN one of the best pedagogical software resources ever developed  
for physics instruction.  But the publishers have been unforgivably  
derelict in supporting and improving the product and have chosen  
instead to milk their once fanatical and ever dwindling user base  
with silly and very expensive "upgrades."  When they abandoned OS X,  
I most reluctantly hung up my IP hat for good.

You can look at some of the modules I wrote on my IP page at

<http://www.csupomona.edu/~ajm/ip.html>

John Mallinckrodt

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

and

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