The finest moments in physics instruction always involves something going bang, blam, or boom, and this is no exception: Purdue's prof Mark French and grad students Craig Zehrung and Jim Stratton built a supersonic ping-pong-ball gun that attains supersonic muzzle velocity:
To demonstrate the conversion of subsonic to supersonic flow, Prof. French and his team designed the gun shown above. The end of the pressure vessel is sealed with laminating tape. Both the nozzle and the barrel are evacuated so the the gas flow is unobstructed. Overall, the gun is a bit less than 12 feet (3.65 m) in length.
To fire the gun, the pressure is increased in the pressure vessel until the tape breaks. French found that two layers of tape ruptured at about 60 psi (414 kPa), and three layers at about 90 psi (620 kPa). The speed of the ball was measured using a high-speed camera viewing the ball moving against a calibrated scale. A typical velocity was a bit over 1,448 km/h (900 mph) – nominally a velocity of Mach 1.23, which is about the top speed of the Soviet-era MIG-19 fighter.
The lead photo should convince the reader that this ping-pong gun is not a toy. The energy and momentum of the ping-pong ball is roughly the same as that of a .32 caliber ACP pistol – not the best choice for defense, to be sure, but quite lethal under the right circumstances.
Ping-pong gun fires balls at supersonic speeds [Gizmag/Brian Dodson]
After years of speculation and wrangling over his remains, Kennewick Man turns out to be closely related to contemporary, local Native Americans after all. Discovered near Kennewick, Wash., in 1996, the skeleton ended up in a tug of war between tribes in the pacific northwest who wanted to bury the remains, and scientists who wanted […]
Our solar system is awesome.
The European Organization for Nuclear Research, or CERN, has been releasing portions of its research to the public for years. This week’s massive 300 terabyte dump of Large Hadron Collider (LHC) data is the biggest yet by a long shot — and it’s all out there, open source, free for the exploration.
You never know when new projects, ideas or opportunities can drop into your lap at a moment’s notice. That may require you to learn a new programming language like Python. Or maybe you need a primer on 3D game development. Or you might realize you could use a serious brush-up on iOS mobile creation.Point is, […]
Isn’t it about time to stretch what your Mac can do? I mean, you’ve got plenty of great programs now…but don’t you think you could use some new tools to get your creative, analytical and organizational juices really flowing? It’s spring, so we cleaned up a whole bunch of super-cool apps lying around and packaged […]
In the world of app development, there’s no greater arena to find success than with Android users. About 80% of the smartphones in use today worldwide operate on the Android operating system, so if you build a great app that Android users love, you’re an international rock star. You’ll be able to make sure your […]