The propagation of a pulse in the real string and rods
  The elastic string (rod) of a large mass M is considered, the left end of which is fixed to a body of a small mass m. The second body of mass m is fixed to the right end of the string. The force of the delta-function form is applied to the left side of the string. We find the propagation of a pulse in the system. The problem is related to the quark-string model of mesons. 
Miroslav Pardy