Re: How do two waves destructively interfere, only to reform and move on?

A transverse wave or a wave of any source is simply transferring energy from one point to another in space and time. One can analyze a transverse wave from two perspectives, (1) as a transporter of energy, and (2) vectors. Regarding your question, Zoki, two transverse waves "cancel out" if you look at them from a vector point-of-view. In a transverse wave, the particles that comprise the wave are moving perpendicular to the direction of the wave packet. Hence, they have displacement and velocity vectors that are perpendicular to the direction of the wave. When two waves "run in to each other" it is their respective vertical displacement vectors that sum up to zero and subsequently arriving at what is referred to as "node",a point of zero vertical displacement. One has to look at a transverse wave in two directions, vertical and horizontal.

Now, in regards to the energy portion of your question, think in terms of conservation of energy. Energy cannot be created nor destroyed, just simply transferred into different forms. The energy of the respective waves will not be dissipated unless there is a dissipative force somewhere within the system. Now granted, the node does not possess any energy in the vertical direction, yet the waves as a whole continue to move with their respective amounts of energy. The only aspect of the wave that "cancels" are the vertical displacementand velocity components. May I suggest that you also refer to any decent physics text for a good quality vector diagram which I have described to you in words.

Hope this helps, Zoki.

Dr. Rutherford

[note added by MadSci Admin: There is a fair number of previous answers in our archives dealing with interference. A search using our search engine should be quite helpful.]