1. The problem statement, all variables and given/known data Starting from system of springs and masses (on picture), fina a force in x direction which n-th mass acts on n+1st mass, if harmonic wave ψ(x,t) is traveling in system. In equilibrium every mass is compressed i acts with force of F0 on masses. Consider a case in boundary of continuum (a→0) a is distance from first to next mass. 2. Relevant equations Second Newton's law, F=m*a ψ(x,t)= Asin(ωt -kx) 3. The attempt at a solution Equation of motion for n-th mass: md2xn/dt2= k[(xn+1-xn) -n*a] -k(xn - xn-1)-n*a] Analogous , for n+1 mass we have md2xn+1/dt2= k[(xn+2-xn+1) -n*a] -k(xn+1 - xn)-n*a] Usually, we guess the soulution. For standard harmonic oscillator, it was x(t) = A cos (ωt + φ). But now, there is also a wave in here. What to do with it? What is his part in this problem? Do i try to guess soultion also? Should i try to find a force from as from above equations or somehow different? What is phyisical meaning of " springs are in equilibrium and every spring is compressed and acts on mass with force of F0? Does that withdraws an driven oscillator?