Waves of the same type are often superposed and encountered simultaneously at a given point in space and time. The properties at that point are the sum of the properties of each component wave at that point. In general, the velocities are not the same, so the wave form will change over time and space.
waves of the same type are often superposed and encountered simultaneously at a given point in space and time the properties at that point are the sum of the properties of each component wave at that point in general the velocities are not the same so the wave form will change over time and space