Bazooka shoots ping-pong balls at Mach speed
A professor who once worked as an aeronautical engineer creates the ultimate ping-pong ball cannon to help students learn about dynamics.
The magic of physics can turn the mundane into something marvelous. Mark French, a mechanical engineering professor at Purdue University, designed a supersonic air-powered ping-pong ball cannon that shoots the lightweight object at speeds so fast I would consider the device a lethal weapon of science.
A ping-pong ball reportedly blasts out of the special cannon at speeds equivalent to Mach 1.23 -- nearly as fast as an F-16 fighter jet. As evidenced in the video below, the high-speed ball can put a clean hole through a plywood paddle, a VHS tape, and other objects. The amount of energy delivered by the Mach-speed ping-pong ball equals the force of a baseball thrown at 125 mph or a brick falling from several stories up.
Drawing upon his previous work as an U.S. Air Force aeronautical engineer, French's incredible ping-pong ball cannon -- made in collaboration with doctoral students Craig Zehrung and Jim Stratton -- echoes the design of a wind tunnel or rocket engine.
The cannon works by connecting a vacuum pump to a long tube through a convergent-divergent nozzle. After drawing all of the air out of the sealed tube, the dense air in the pump becomes so pressurized that it breaks its own seal and releases back into the tube -- sending the ball forward with incredible momentum.
"That hourglass-shaped nozzle is similar to what is used in fighter jets," French said in a statement. "When the pressurized air rushes through the bottleneck it accelerates to supersonic speed as it helps propel the ball through the clear PVC barrel."
In a conversation with CNET, French explained why the project helps teach students about physics: "My goal for the ping-pong gun is to make dynamics (one of the subjects I teach) fun. It's loud and it does something completely unexpected. As a result, students get enthused and I have an opportunity to teach them. It's all about creating a learning moment."