I replaced the attractive magnetic poles by electrified pith balls
(sphere A and sphere B) and performed an Interactive Physics
simulation (see the details below). The result is that the two
pith balls had no trouble of finding the equilibrium position;
they did not jump to each other suddenly, as my bar magnets
did.
Does it mean that Interactive Physics is not good for this kind
of simulation or that the experiment was not good enough to
prevent small sidewise and vertical oscillations?
Here are the details (there is nothing special about them)
1) Spring constant k=30 N/m, spring natural length 1.4 meters.
2) Mass of the suspended sphere A was 0.5 kg, its charge was
+5*10^-5 C. In the absence of the second sphere B the initial
location of A was x=0, y=+1 meters.
3) The second sphere B was kept at a fixed position (x=0, y=-1m).
The mass of B was 0.5 kg, its charge was -5*10^-5 C.
4) Strong damping was imposed by setting air resistance at
"high" and by imposing 50 kg/m^2.
5) The electrostatic forces were turned on without turning off
gravity.
6) As soon as the RUN button is pressed the sphere A starts
moving toward the sphere B, performs several oscillations
and remains at rest at y=0.506 meters.
Ludwik Kowalski