  The Ping Pong gun or Ping Pong bazooka has been a popular and compelling tool
for physics education. However, the design necessarily means the ball emerges
at subsonic speed. The design has been modified to include a pressure chamber
and a convergent-divergent nozzle, similar to the design of some supersonic
wind tunnels. This modification results in supersonic speeds. The current
design has achieved a launch speed of 406 m/sec, about Mach 1.23.
