Simulation of the Doppler Effect

Initially the speed of the sound source, the red dot, is set to zero. As time progresses the peak of the wavefronts produced by the source are shown. The wavefronts are circles with the dot as an origin, and move out at the speed of the wave.

Time is in seconds and is displayed constantly. If you click and hold a cross hairs appearrs and the coordinates of the crosshairs are shown. Time is in seconds, distances in m Start the animation with the "Run" button, The same button allows you to "Stop" the animation

  1. Make measurements to determine the wave speed.
  2. Make measurements to determine the wavelength of the source.
  3. From these find the frequency of the source.
  4. Now adjust the slider to a speed of 0.5, meaning source speed = half the speed of the wave. Run the animation for several seconds.
  5. Look to the right of the source. Measure the wavelength in this region where the source is approaching the detector. The speed of the wave is the same as before. Compute the observed frequency. Check that Doppler's formula works for this case.
  6. Look to the left of the source. Repeat the steps of the previous part in this case where the source is moving away from the detector.

Shock Waves

  1. Adjust the slider to 1.3 so that the source is moving faster than the speed of the waves. Run the simulation for several seconds and then sketch what you see.
  2. Finally, make the speed 1.8 and run the simulation for several seconds. What has changed from the previous part?
Check out this picture of a shock wave forming around a jet. That site lets you download a video of the event. Estimate the speed of the jet from the shape of the shockwave.