I wanted to ask the following question: If we change the medium of the wave (lighter or heavier) , how it will affect the particles velocity of the standing mechanical wave ? In my exam , there was a function's graph of one of the particles (of the standing wave) described with the coordinates y(displacement) and t(time). I claimed that the slope of the function's graph represents the velocity of the particles has to be changed because the mass of the medium changed. My teacher claims that my answer is incorrect and the velocity of the particles won't be changed because of the fact that the question is about a specific kind of wave : a standing mechanical wave, so the particles velocity won't be affected by the change of the medium's mass. So who's right and why?