Expert: Paul Soderman - 4/17/2005

Question
Thank you for your time.
I became interested in shock waves after seeing a picture of an F-14 creating some kind of cloudform upon reaching Mach 1.
I learned it likely had something to do with the thermal dynamics of the airfoil but that is still being debated I hear. In any case, I've seen photo's of visible shock wave distortions made by land vehicles exceeding the speed of sound, I wondered if it were possible for us couch potatoes to create shock waves by spinning noisemakers at the speed of sound. (Around a 12 foot circumference at 6000 RPM's). I believe the possible sound powered visual special effects of such a thing would fetch a good price on EBay. (anything that can help me quit my day job would be appreciated). Would the sound waves become polarized if they had a frequency of 6000 Hz. I realize that the book says its not possible to polarize a sound wave.

I'll settle for dupicating the Prandtl-Glauert Singularity thing by revolving air foils in the same manner, (Around a 12 foot circumference at 6000 RPM's). If thats at least possible.  

Answer
Yes Jeff - any object moving at or above the speed of sound will create a shock wave.  It doesn't have to be a noise maker, the shock itself makes plenty of noise.  The trick is in getting something to move that fast...safely.  And no, sound waves will not poloarize like light waves can.

Paul