ABSTRACT
To check if the sphere is behaving itself and is going to cooperate as an actor in this drama, set the 3D window to front view (number pad 1) and, with the cursor in the 3D window, press the P key. This puts the 3D window into play mode. The sphere should descend in the window and disappear out of sight. Press Esc to return the sphere to center stage in the window. You have just proved that the sphere actor is behaving itself; gravity has taken hold of the sphere and caused it to fall. Since there is nothing below the sphere to obstruct its motion, it falls to infinity. We had better do something to correct this.
