Waves: fundamental frequency of taut cable

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SUMMARY

The fundamental frequency of a taut cable supporting a sailboat mast can be calculated using the formula f = n/(2L) * sqrt(T/μ). In this case, the cable has a length of 12 m and a linear mass density of 0.35 kg/m. The tension in the cable must be determined, as the provided force of 160 N is insufficient for accurate calculations. The correct approach involves calculating the actual tension based on the cable's deflection and the forces acting on it.

PREREQUISITES
  • Understanding of wave mechanics and fundamental frequency
  • Familiarity with tension and linear mass density concepts
  • Knowledge of mathematical manipulation of physical formulas
  • Ability to interpret physical scenarios in terms of physics equations
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  • Calculate the actual tension in the cable using the deflection and applied force
  • Learn about wave propagation in strings and cables
  • Explore the relationship between tension, mass density, and frequency in vibrating strings
  • Study the effects of boundary conditions on the fundamental frequency of cables
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Students studying physics, particularly those focusing on wave mechanics, engineers working with structural supports, and anyone interested in the dynamics of vibrating cables.

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1. Homework Statement

The wire cable supporting the mast of a sailboat has a length of 12 m and a linear mass density of 350 g/m. When pushed sideways at its midpoint with a force of 160 N, the cable deflects by 9.5 cm. What is the frequency of the fundamental mode of vibrations on this cable?

Homework Equations


λn.fn=v and velocity:v=sqrt(T/μ) , lemda λn=2L/n and L= length of string
fn=n/2L . sqrt(T/μ)
fundamental≡ the first mode ⇒ n=1

The Attempt at a Solution


for n=1
f=1/(2*12) .sqrt (160/0.35) =0.89 Hz
but it is incorrect why??
 
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In the equation you use, what are each of the terms? ( IE. what do the letters f, n, L, T and μ stand for?)
Which of these are given?
What other information are you given?
How will you work out the term, which is not given?

As a hint, you don't use one of the given values and you mis-use one of the given values.
 
Merlin3189 said:
what do the letters f, n, L, T and μ stand for?)
Which of these are given?
Any Help said:
velocity:v=sqrt(T/μ)
T=tension=160N
μ=linear mass=0.35kg/m
Any Help said:
L= length of string
Any Help said:
fundamental≡ the first mode ⇒ n=1
f is the frequence
 
Any Help said:
T=tension=160N
The tension should be the tension in the cable.
The value 160N is the force used to displace the cable sideways by 9.5cm.
The tension in the cable would be much greater. (A mast over 12m high would hardly be supported by a tension of 160N on each side.)

So you need to see how you can use the information given, to calculate the tension in the cable.
 

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