Monday, March 02, 2009

The Detonators


It was a rainy weekend, so we enjoyed a couple of episodes of "The Detonators." It's a show about demolishing structures. We decided to put the information learned on the show to good use in checking how large a wedge one needs to make in a cylindrical tower (like a toilet paper tube) to bring down the building. According to the formula, the size of the wedge, W, needed to bring down a structure like this is

W = D^2 / 2 H where D is the diameter of the structure and H is the height. We quickly measured our tube to learn that its diameter is 2" and its height was 8". Using the formula, it revealed that we need a 1/4" wedge or larger. To test the theory, we first cut a too small wedge in the tube and simulated the explosion by placing a block under the tube in the area where the wedge was cut out. Removing the block simulated the explosion. The theory seemed to work, the tube didn't fall. Next, we cut a larger wedge, one that was just a bit bigger than W. Redoing the experiment, we got the expected result--the tube fell.

Then we did another experiment. We chopped down the height of the tube. According to the formula, the old "successful" wedge will no longer work for the shorter tube. A test confirmed this. We then expanded the wedge and obtained a positive result.

Finally, we tried some building implosions. The one that we were able to simulate caused the building to fall in a particular direction by means of timed explosions starting in the direction you want the building to fall. To simulate this, we built a base of small blocks connected by tape. We then placed a sheet of wax paper over the base to enable us to pull out the blocks in a timed fashion. Finally, we built the building on top of the wax paper from colorful blocks. We also set up some nearby buildings that were not supposed to be harmed if the explosion went according to plan. This test was also successful. We triggered the desired chain reaction.

The one that we weren't able to simulate was an implosion of a building into its own footprint. They do this with timed explosions in the center of the building and moving outward. Despite many attempts to get the timing right with blocks, we couldn't do it. Still, it was very cool to put the principles of the detonators to the test on our small scale experiments.

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