Paradox of a particle’s trajectory moving on a string


This paper deals with the paradoxical properties of the solution of string vibration under a moving mass. The solutions published to date are not simple enough and cannot be applied to investigations in the entire range of mass speeds, including the overcritical range. We propose a formulation of the problem that allows us to reduce the problem to a second-order matrix differential equation. Its solution is characteristic of all features of the critical, subcritical, and overcritical motion. Results exhibit discontinuity of the mass trajectory at the end support point, which has not been previously reported in the literature. The closed solution in the case of a massless string is analyzed and the discontinuity is proved. Numerical results obtained for an inertial string demonstrate similar features. Small vibrations are analyzed, which is why the effect discussed in the paper is of purely mathematical interest. However, the phenomenon results in complexity in discrete solutions.

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Correspondence to Czesław I. Bajer.

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Dyniewicz, B., Bajer, C.I. Paradox of a particle’s trajectory moving on a string. Arch Appl Mech 79, 213–223 (2009).

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  • Moving mass
  • Vibrations of string
  • Inertial load