Designed by Fu-Kwun Hwang http://www.phy.ntnu.edu.tw/ntnujava/ remixed by lookang Reference taken from Juan M. Aguirregabiria's http://www.compadre.org/osp/items/detail.cfm?ID=7902 and Andrew Duffy's http://www.compadre.org/osp/items/detail.cfm?ID=9982 which made the remixing of this simulation a lot easier :) lookang thanks to the all of them great physics teachers. For more info: http://weelookang.blogspot.sg/2011/09/ejs-open-source-1-dimension-doppler.html

The Doppler effect

The Doppler effect describes the shift in frequency of a wave that is produced by the motion of either the wave source or the observer of the wave (or both).

A sound source is moving with velocity v along the horizontal axis. Every period T a wave front leaves the source and travels with velocity c with respect to a medium (say air), assuming no air motion. A detector is located at position (x, y) and may move with velocity (dx/dt, dy/dt). To promote ease of learning, only the x direction is enabled, thus, making exploration confined to 1 Dimension.

You may change via sliders and edit the values of the aforementioned quantities, as well as the time interval dt between animation frames.
The source and detector position may also be chosen by means of the sliders.
Press Initial to set t = 0 and the source at its initial position.
Press Continue to start or continue the animation.
Press Stop to pause the animation, and Reset to recover the default settings.

In the graphics window below the animation a vertical red (green) bar is displayed each time a wave front leaves the source (reaches the detector).