Labs / Physics
Doppler Effect
A sound source glides across the room, ringing out a fresh circular wavefront every fraction of a second. Drag anywhere to fling it in a new direction, or push the speed slider up — the waves squeeze together in front and spread out behind, raising the pitch ahead and lowering it in your wake.
v 0.60 Machf ahead 1100 Hzf behind 275 Hz
What to try
- Why do the wavefronts pile up in front of the source but fan apart behind it?
- An observer standing dead ahead hears one pitch; someone behind hears another. How far apart are the two frequencies at Mach 0.5?
- Push the speed to exactly Mach 1. What happens to every wavefront right at the nose of the source?
- Go supersonic. Where does the sharp V-shaped shock cone come from, and why does it get narrower the faster you go?
- Let the source bounce off a wall. Does the crowded, high-pitch side switch to the other end the instant it turns around?