1B-2. Suppose an infinite string is constrained so that a section in the middle is deformed into one cycle of a sine function as shown in the figure, i.e., \$\xi = \sin x\) for $|x| \le \pi$. The string is quiet up until time $t = 0$, at which point the constraint is released.
(a) Give the analytical solution of the problem, i.e., find $\xi(x, t)$ for $t > 0$.
(b) Sketch the string displacement $\xi(x)$ for a sequence of times $t$.
