# Wave equation as a consequence of Newton's second law

How the linear wave equation is a direct consequence of Newton's second law applied to any element of a string carrying a travelling wave?

• Try to analyse a small infinitesimal length of the string. Draw its free body diagram and use Newton's second law. You will surely get something out of that.
– user243267
Dec 1 '19 at 16:04

In the second reference is a way to derive the wave equation using only $$f(x-ct)$$ and $$f(x+ct)$$, not requiring any physical situation at all.