The situation in the Penetrable Solid display is one of those things you can do with mathematical modeling that would be hard to duplicate in the real world. The purpose of this display is just to illustrate the relationships among the position of the movable object, the potential energy of the system and the force the moving object experiences. In this made up universe the gravitational constant is 2.09 rather than 6.673e-11, the masses of both objects are 1kg. The blue object is attached to the origin of the reference frame and the scale of the energy and force plots is 1:1 with the distance scale so that the cursor values of energy and force may be read directly. I mention this only if you want to try to get quantitative information from the plots.