WaveAdd

Add two waves (transverse and/or longitudinal; sine, square, or triangle) and view the resulting wave.
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.
Use presets that show beats, standing waves, constructive or destructive interference.
If you like, see constantly updated values and equations of position, velocity, and acceleration for all waves.