1. The problem statement, all variables and given/known data the energy transferred per second by a progressive waves is directly propotional to the square of its amplitude, if two waves are in phase and superposed, the energy per second transferred by the resulatant wave propotional to A.) the sum of amplitude. B). The diffrenece of the amplitudes. 2. Relevant equations 3. The attempt at a solution my ans is A. since when two waves superposed at a pointy, the resultant displacement is vector sum of individual displacement of two waves. BUT the ans given is B .