[ODE] friction, normal force

[Gabor Monostori]

Hi!

I have a question, I suppose it isn't difficult to answer it. I've
read in the manual that there is two kinds of friction approximation,
and the dContactApprox1 works quite good as Coulomb friction. So I set
this

contact[i].surface.mode := dContactBounce  and dContactApprox1;

and I placed a small box on a table and gave it initial velocity in x
direction (the table is put into the simulation as PdxGeom) . I expect
that the equation

m * a = - mu * m * g           =>             a = -mu * g

will come true, but I found that the acceleration still depends of
the mass. It seems that the normal force doesn't equal to m*g.
Shouldn't it equal? What can I do to make the simulation correspond
with the equation?

Thanks for the help,
Gabor