Saturday, February 16, 2013

Boys and their (supersonic ping-pong ball) toys

I'm hugely amused by the efforts of a Purdue University professor to use fun and games as a method of teaching physics.  Would you believe he's come up with what Popular Mechanics calls a '900-MPH Supersonic Ping-Pong Bazooka'?

For years, Mark French has been using the regular subsonic version of the gun to teach kids about physics.

. . .

On a hunch, French and his students modified the gun with a convergent–divergent nozzle, the type used in rocket engines and supersonic wind tunnels to accelerate air flow. The revamped gun shoots pressurized air through the hourglass-shaped nozzle. As the air travels through the nozzle's choke point, compression accelerates the air. It blasts the ping-pong ball outward at 900 mph (the speed of sound is roughly 765 mph).

. . .

Once the engineers got the bazooka up and running, they tested it on all sorts of materials, including VHS tapes, 3/4-inch plywood, stereo speakers, and even a sheet of steel. "The ball didn't go through the steel, but it put a whopper of a dent in it," French says. "Normally what happens is the ball comes out in pieces—it's shattered but not deformed. For this one, it melted and buckled. I didn't expect that."

There's more at the link.  Here's a short video clip of the beast being test-fired.

A longer video presentation, giving more details, may be found here.

Kudos to Prof. Mark French for a very original teaching tool!



ahovelDriver said...

Shoots at 900 mph? Shouldn't be too long before the 'assinine' BATF (Bureau of Assholes Taking Firearms) shows up to haul him, and all his students-and-research assistants away.

Wraith said...

SD's right. This'll be illegal about 20 minutes after DiFi and Obummer hear about it.