To see the effects more closely, and to test the theory, we used several toy models. First, we piled up 100 small plastic bricks and destabilized the base of this tower, so that it falls naturally, rotating around the bottom point. Then, we video-taped the motion of this "falling chimney", and we analyzed where the structure starts to break. The picture below is a frame taken from one of our videos.
As it can be seen from this picture, the model is breaking at about 30-35 degrees (estimated by looking at the angle between the vertical and the upper part of the chimney), and at a fractional height r/H = 0.40. This is in good agreement with the theory outlined in the previous page. You can find the video of this experiment here, and analyze it frame by frame.
In another model, we stacked 24 wooden blocks, to construct a smaller strucure, and then we proceeded like in the previous case. Here is a picture of this second chimney breaking:
This time the chimney broke at a much smaller angle (around 10 degrees), and exactly at the middle (r/H = 0.50). The position of the rupture still agrees with the last figure in the previous page. You can watch the video of this model here.
We recently finished a second paper on the subject. We improved and refined the analysis of the digital video movies, by using a popular video capture software (VideoPoint 2.5). As it can be seen in the following figure, the software can follow the different rotations of the top and bottom portions of the structure, showing the point where the tower begins to bend.
Here are some links related to the Falling Chimney problem and to the "Falling Chimney" demonstration, which represents the first step to the full understanding of the problem.
For more information and additional details, please refer again to our first paper and the extensive bibliography at the end of it. If you have questions or comments, feel free to contact us.