Here you can visualize the Doppler effect. It's easy: Just click anywhere within the gray area and drag the mouse. An arrow representing the source velocity vector will appear. The speed of the source divided by the sound speed (= Mach number) is also displayed numerically. Let go of the mouse, and your source will move across the scrren, emitting waves.
Hint: Press the "s" key and the animation stops. Press it again, and it continues.
© W. Bauer, 1999