WaveAdd

Adds two waves (transverse or longitudinal; sine, square, or triangle)   
Change the frequency, wavelength, and amplitude of each wave on the fly.
Select unit circles, amplitude bars, reference line, wavelength markers, amplitude markers.
Slow, merge, or stop the waves. 
Presets demonstrate beats, standing waves, constructive or destructive interference.
Constantly updated values and equations of position, velocity, and acceleration.