The speed of a waves on a string in Simple harmonic motion

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SUMMARY

The speed of a wave in simple harmonic motion on a string is defined by the equation $$v= \sqrt{\frac{F}{\mu}}$$, where "v" represents the horizontal velocity of the wave, "F" is the tension force in the string, and "μ" is the linear mass density. The tension force can be approximated as acting in the horizontal direction, and the difference between horizontal tension and resultant tension is negligible for small vertical displacements. This approximation allows for a simplified analysis of wave speed without significant loss of accuracy.

PREREQUISITES
  • Understanding of wave mechanics
  • Familiarity with tension forces in strings
  • Knowledge of linear mass density (μ)
  • Basic principles of simple harmonic motion
NEXT STEPS
  • Study the derivation of wave speed equations in string theory
  • Explore the effects of tension on wave propagation in different materials
  • Learn about the relationship between displacement amplitude and tension changes
  • Investigate the applications of wave speed in musical instruments, particularly strings
USEFUL FOR

Physics students, educators, and anyone interested in understanding wave dynamics in strings, particularly in the context of simple harmonic motion and musical acoustics.

annamal
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The speed of a wave in simple harmonic motion on a string is $$v= \sqrt{\frac{F}{\mu}}$$ where v= the horizontal velocity of the wave on a string.
Is the F the horizontal force or the resultant force (combination of Fy and Fx)?
 
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annamal said:
The speed of a wave in simple harmonic motion on a string is $$v= \sqrt{\frac{F}{\mu}}$$ where v= the horizontal velocity of the wave on a string.
Is the F the horizontal force or the resultant force (combination of Fy and Fx)?
That "F" is the Tension force:

1663170680261.png

http://hyperphysics.phy-astr.gsu.edu/hbase/Waves/string.html
 
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annamal said:
The speed of a wave in simple harmonic motion on a string is $$v= \sqrt{\frac{F}{\mu}}$$ where v= the horizontal velocity of the wave on a string.
Is the F the horizontal force or the resultant force (combination of Fy and Fx)?
It does not matter. To the approximation that is used to derive the wave equation, the difference is negligible.
 
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Orodruin said:
It does not matter. To the approximation that is used to derive the wave equation, the difference is negligible.
Ok, not sure how the tension in the x direction can be approximated as the resultant tension
 
annamal said:
Ok, not sure how the tension in the x direction can be approximated as the resultant tension
The vertical displacement amplitude is assumed to be small in those derivations, so the tension in the string is not affected (in magnitude) by the wave passing by. Does that help?
 
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For a typical steel string guitar a 2mm displacement at the midway point translates into an increase in string tension on the order of one part in one thousand. So it's a pretty good approximation to just assume that the tension doesn't change. Then you can focus on the vertical force and come up with a straightforward equation for the speed of the wave.
 

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