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FontSizes 18;
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Text "Demonstration of Doppler effect.

Version 0.35
To do:
(i) Switch to mod (instead of a\in {1,2,...})

V – speed of wave; f – frequency of wave.";
Color 5;
MathPaneSlider 1;
Expr V=slider([0,5,5]);
Color 6;
MathPaneSlider 9;
Expr f=slider([0,10,40]);
Text "Speed of observer; observer location.";
MathPaneSlider 20;
Expr O=slider([-5,5,40]);
Color 3;
Expr vector(x,y)=vector(2+O*n,0);
Text "S – speed of source; location of source";
Color 3;
MathPaneSlider 2;
Expr S=slider([0,5,40]);
Color 2;
Expr vector(x,y)=vector(S*n,0);
Text "Spacing of source emission points is D=ST=S/f, where T=1/f is the period of the source:";
Color 4;
Expr D=S/f;
Text "Pulse emitted at aD at a time aD/S = a/f after t [i.e. n] = 0; a labels emitted pulses.  Wave fronts emitted at aD:";
Color 3;
Expr sqrt([x-(a*D)]^2+y^2)=V*[n-a/f],in(a,set(0,1*ldots*40));
Text " Same pulses absent source motion:";
Color 17;
Expr sqrt([x]^2+y^2)=V*[n-a/f],in(a,set(0,1*ldots*40));
Text "<size=16>The ground and an observer on the ground:";
Color 17;
Expr y<-0.5;
Expr H=slider([-5,20]);
Color 8;
Expr vector(H,-0.5);
Text "<size=12>

Author: David A. Craig <<http://web.lemoyne.edu/~craigda/>";
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