It's probably a universal fact that teaching physics concepts goes down a lot easier when there is a little firepower involved used to help illustrate cause and effect. In this case, a Purdue engineering professor worked with his students to create a ping-pong ball gun that shot one of those little plastic balls at Mach 1.23, straight through a paddle.
In this video, Professor Mark French walks us through how he created a ping pong ball gun from directions found on the Internet. He modifies the basic air gun to amp up its capabilities, including adding a bell shaped "de Laval" nozzle that appears in supersonic rocket nozzles to create superior air flow. Plus, while regular air guns rely on atmospheric pressure, French raised the stakes to supersonic speeds by pressurizing his air chamber to over one atmosphere.
French illustrates and explains each of the concepts that went into the modifications, and while you may still remain skeptical that a little plastic ball could pass through wood, don't worry - you will be rewarded.
It's a pretty cool trick, all in the name of science.
Via Tech News Daily