1. The problem statement, all variables and given/known data The displacement y of a long string at position x and time t is given by y(x,t) = cos (kx-wt) + sin (kx-wt) Show that the motion of the string at any point is SHM. 3. The attempt at a solution As far as i know this is something to do with adding 2 waves together and in this case we have a sinusoidal wave and a cosine wave. If one wave is the reflection of the other then a standing wave will develop, and i think that in this case a standing wave will develop and that would mean that the motion of the string is SHM. Is that correct? Would there be a better explanation as to why the motion is in SHM. p.s not homework, just past exam question.