We need to proceed in three steps.
First create a new movie clip. In frame 1, put this initializing code: 

damp = 0.05;
x_def = GetProperty(“foo”, _x);
stiff = 0.2;
brown = 0.2;
gotoAndStop(“Move_x”);

This code sets the values of physical parameters damp, x_def, stiff and brown and goes directly to the temporal loop (see below).