Two long wooden beams are set up, one on top of the other, forming a "chimney" as shown in the photograph at the left below.
A very gentle increasing force is applied to the center of the top beam until the chimney just begins to topple. When the toppling ensues on its own, the two sections are lined up straight. As the chimney topples, it might assume one of the configurations shown in the drawing below. That is, the upper section might fall behind, as shown in (a), the upper section might move ahead, as shown in (b), or the two sections might rotate together as shown in (c). What actually happens when the chimney begins to fall is the question for this week.
After the chimney begins to topple, the configuration that it assumes will be:
Click here for Answer #43 after December 18, 2000.
