Comment on: 'Peculiarities in the energy transfer by waves on strained strings' (Phys. Scr. 88 065402)

Rowland, David R. (2015) Comment on: 'Peculiarities in the energy transfer by waves on strained strings' (Phys. Scr. 88 065402). Physica Scripta, 90 8: 1-8. doi:10.1088/0031-8949/90/8/087002


Author Rowland, David R.
Title Comment on: 'Peculiarities in the energy transfer by waves on strained strings' (Phys. Scr. 88 065402)
Formatted title
Comment on: 'peculiarities in the energy transfer by waves on strained strings' (Phys. Scr. 88 065402)
Journal name Physica Scripta   Check publisher's open access policy
ISSN 1402-4896
0031-8949
Publication date 2015-08
Sub-type Critical review of research, literature review, critical commentary
DOI 10.1088/0031-8949/90/8/087002
Volume 90
Issue 8
Start page 1
End page 8
Total pages 8
Place of publication Temple Way, Bristol, United Kingdom
Publisher Institute of Physics
Collection year 2016
Language eng
Formatted abstract
Contrary to what is conventionally assumed, to determine the location and flow of potential energy in vibrating strings, the effects of longitudinal displacements need to be taken into account, even when these displacements are much smaller than the associated transverse displacements. In a recent paper, Butikov (2013 Phys. Scr. 88 065402) investigated the implications of this fact and found an infinitely long transverse travelling wave with associated longitudinal disturbance where the associated potential energy density apparently travelled along with the transverse wave at the transverse wave speed. This finding contradicts previous results with transverse pulses which show that in the presence of a unidirectional transverse travelling wave, potential energy propagates at the longitudinal not transverse wave speed. This apparent contradiction is reconciled in this paper by considering a finite length of Butikov's infinitely long travelling wave. It is shown that the energy flow found by Butikov is the net effect of potential energy propagating in both directions at the longitudinal wave speed, a fact that is hidden when a wave of infinite length is considered. This conclusion is supported by a general theoretical result. In addition, it is shown that Butikov's claim that the part of the potential energy density proportional to the first spatial derivative of the longitudinal displacement represents a relocation of the pre-existing potential energy which the string has due to the initial stretching required to create a tension in the string is only valid in a limited number of situations. In most of the examples considered, the term represents a relocation of the potential energy of the wave, though in general it can have many different physical interpretations.
Keyword Energy propagation
Taut strings
Waves
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Critical review of research, literature review, critical commentary
Collections: UQ staff Publications
Official 2016 Collection
 
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