1. The problem statement, all variables and given/known data Just looking back through my notes and it looks like I'm missing some. Just a few questions. For one example in the notes I have the wave utt-c2uxx + u3 = 0 and that the energy density 1/2u2t + c2/2u2x + 1/4u4 I have that the differential form of energy conservation is εt = μx + (wave equation)μt = μx for solutions. First question, what is the integral form of energy conservation? The notes then say that here μ = c2utux. Why is this? Also what is the difference between global and local form of energy conservation? Is it just that local has finite limits? Are there any websites or online notes that might have some of this info? I searched a lot but can't find much Thanks!