Chapter 18, Problem 13PQ

(a)

To determine

To show that the resulting wave on the string is given by $y\left(x,t\right)=\left[2y_{\text{max}}\cos \frac{\phi }{2}\right]\sin \left(kx-\omega t+\frac{\phi }{2}\right)$.

(b)

To determine

The amplitude of the resulting wave when $\phi =0$, $\phi =\pi /2$, and $\phi =\pi$.