You have got to love engineering students. They (and their professors) come up with some interesting ways to prove and disprove theories. Granted it is not all fun and games, but it looks fun when they get done. I don’t know about you, but when I was in college our projects were not nearly as fun as what some engineering students at Purdue’s College of Technology have been up to. Mark French, associate professor of mechanical engineering technology, and two of his PhD students are doing things with ping- pong balls that, frankly, I didn’t think were possible.
French’s ping-pong gun has been frequently used to teach younger kids about Physics. The gun consists of a ball in a PVC tube sealed on both ends, and a pump that removes air and creates a vacuum. After pumping they break the seal on one end of the tube to release the ball. Pretty simple. But that only got the ping-pong ball to 400 MPH. So to speed it up they added a nozzle normally used to accelerate airflow in wind tunnels. The result is a ping-pong ball that moves 900 MPH. Yes, 900 MPH. The real purpose of the experiment was to “demonstrate how a de Laval nozzle (also called a convergent-divergent nozzle) converts subsonic gas flow into supersonic flow” as they say on their blog. OK, sure. I just like the fact that in the video below a ping-pong ball gets shot through 5 cans. Watch the video and I think you’ll be impressed. If you want more of the who, what, how visit the MET section on Purdue’s website. There is also a video demonstration of a ball actually going through a ping-pong paddle. Hats off to Mark French and his students for showing us how velocity can change everything.