string

Hi,

I have to use Hamilton pricinple to evaluate the diff. equation of motion of a string. As shown in the figure below, the string is hanged from one end and is free at the other. The flexural stiffness of the string is negligible.

I have a problem with the potential energy of the string! required in the Hamilton principle. Since the flexural stiffness of the string is assumed to be negligible, is there any other term for potential energy?