To apply the principle of superposition to overlapping waves, you should of the individual waves. a) add the wavelengths b) multiply the frequencies c) add the vector displacements d) add the frequencies sound travels at a speed of 344 m/s through air at 20°c. what is the second harmonic of an open pipe of length 1.40 m filled with air at 20°c? 123 hz 246 hz 492 hz 377 hz