1. A string 4 m long is stretched, resulting in a wave speed of 60 m/s. It is given an initial displacement of 0.2 sin πx/4 and an initial velocity of 20 sin πx/4. Find the solution representing the displacement of the string.
2. A 4-m-long stretched string, with a = 20 m/s, is fixed at each end. The string is started off by an initial displacement u(x, 0) = 0.2 sin πx/4. The initial velocity is zero. Determine the solution for u(x,t).