1. At the end of the string, can the amplitude of the string ever exceed the amplitude of the pulse reflecting from that end? In what situation?
2. When a pulse reflects from a fixed end, as well as when destructive interference occurs for identical pulses, the string is flat at one instant in time. What causes the pulses to re-emerge from the flat string? Note that the string is flat during reflection only when the pulse is symmetric, as it is here, and is during destructive interference only when the pulses are mirror images, as they are here in the case of identical pulses.