\( y = \, y_m \, sin \; \omega t \)
\( y_s = \, y_m \, sin \;\omega t \)
\( y_p = \, y_m \, sin \; \omega\; ( t - {x \over v} ) \)
$$\phi = \frac{x}{\lambda} 2 \pi $$
\( y_p = \, y_m \, sin \; (\omega\; t - \phi ) \)
\(x = \, vt + \, x' \)
\( y = \, y' = f(x- vt) \)
\( y = \, y_m \, sin \,\omega t \)
\( y = \, - y_m \, sin \,k\, x \)
\( k = \frac{2 \pi}{\lambda} \)
\( y = \, - y_m \, sin \;k\, (x-vt) \)
