(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

2. At time t = 0, the displacement of an inﬁnitely long string is:

y(x, t) = sin(pix/a) for −a ≤ x ≤ a

The string is initially at rest. Using d’Alembert’s solution for speed c, sketch the displacement of the string at t = 0, t = a/2c, and t = a/c.

2. Relevant equations

3. The attempt at a solution

So I see how to do this...my only problem is as follows:

D'Alembert solutions says y = f(x-ct) + g(x+ct)..

but we don't know if the wave goes left or right..so how do i know whether to sub in x-ct for x or x+ct for x? thanks!

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# Homework Help: Sketch the displacement of the string

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