Some remarks on the string problem treated by Singh and Demin

Abstract

The problem of the motion of a string attached to a satellite on a circular orbit, as treated by Singh and Demin, is reconsidered. In their paper they discuss problems of uniqueness and stability. In particular the radial equilibrium positions were found to be unstable in a certain sense. In the present paper it is shown that: (i) with the stability definition used by Singh and Demin the equilibrium of a string hanging in a uniform gravity field would also be unstable; (ii) a definition of stability more appropriate for continuous systems would establish the stability of the string both in orbit and in a uniform gravity field.