Wave Equation for Travelling and Standing Waves
\[v=f \lambda\], where
\[v\]is the wave speed
\[f\]is the frequency
\[\lambda\]is the wavelength
This equation is true for both traveling waves and standing waves - waves on a stretched spring fixed between two points, or sound waves in a pipe. But standing waves don't travel, so how can the standing wave have a speed? You should think of wavelength and frequency for longitudinal and standing waves as in the table below.
|Standing||Number of complete up and down cycles per second||Twice the distance between successive nodes, or this distance between two ppoints moving at thew same speed in the same direction ( up and up, or down and down)|
|Traveling||Number of complete wavelengths a particular wave moves per second - the above definition does not work because travelling waves do not move up and down. The whole waveform moves, like a train||Twice the distance between a peak and a trough - the above definition will no do because all points on a travelling wave are moving at the same speed in the same direction )horizontally for a water wave)|