1. The problem statement, all variables and given/known data The cross-section of a long string (string along the x axis) is not constant, but it changes wit the coordinate x sinusoidally. Explore how a wave, caused with a short stroke, spreads through the string. 2. Relevant equations Relevant is the one-dimensional wave equation, where the wave speed c is not a constant (i.e. c=√T/ρS, where T is the string tension, ρ is the density of the string, and S is the cross-section). The cross-section: S=S1+S2*Sin[x] 3. The attempt at a solution I thought about using Laplace transformation so that I get an ordinary differential equation. I also have trouble with the initial conditions, I don't know what is meant by short stroke, or if it really matters.