What is the length of a vibrating metal wire at its third harmonic frequency?

In summary, the question asks for the length of a metal wire vibrating at its third-harmonic frequency, where at a distance of 0.32 m from one end, the amplitude is one quarter of the maximum amplitude. The wire is assumed to be fixed at both ends, with the starting point being a node. The hint provided states that the third harmonic will have a wavelength equal to 2/3 of the length of the wire and the maximum amplitude is 2A, not A. This suggests that both ends of the wire are nodes.
  • #1
goonking
434
3

Homework Statement


A metal wire is vibrating at its third-harmonic frequency. 0.32 m from one end, the amplitude is equal to one quarter the maximum amplitude. Find the length of the wire.

Homework Equations

The Attempt at a Solution


I don't quite understand the question, it says 0.32m from one end, is that from the start to the first node?

the amplitude going to be 1/4 its maximum where sin(x) = 0.25, correct?
 
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  • #2
goonking said:
A metal wire is vibrating at its third-harmonic frequency. 0.32 m from one end, the amplitude is equal to one quarter the maximum amplitude. Find the length of the wire.
It is not clear to me whether the wire is fixed at either or both ends. I'd guess it's fixed at both. If so, the 'start' is a node, and .32m is the distance from there to the given point.
goonking said:
the amplitude going to be 1/4 its maximum where sin(x) = 0.25, correct?
It depends what you mean by x.
 
  • #3
haruspex said:
It is not clear to me whether the wire is fixed at either or both ends. I'd guess it's fixed at both. If so, the 'start' is a node, and .32m is the distance from there to the given point.

It depends what you mean by x.
if it helps, the hint the question has is : "The third harmonic will have a wavelength equal to 2/3 of the length of the string. Also, *note to self* the max-amplitude of this wave is (2A) not (A)."
 
  • #4
goonking said:
if it helps, the hint the question has is : "The third harmonic will have a wavelength equal to 2/3 of the length of the string. Also, *note to self* the max-amplitude of this wave is (2A) not (A)."
So what does that tell you about whether one or both ends of the string are nodes?
 

1. What is the Third Harmonic Frequency?

The third harmonic frequency is a term used in physics and engineering to describe the third multiple of the fundamental frequency of a periodic wave. It is also known as the third overtone or the third harmonic.

2. How is the Third Harmonic Frequency calculated?

The third harmonic frequency can be calculated by multiplying the fundamental frequency by 3. For example, if the fundamental frequency is 100 Hz, the third harmonic frequency would be 300 Hz.

3. What is the significance of the Third Harmonic Frequency?

The third harmonic frequency is important because it affects the overall shape and quality of a periodic wave. It is also used in the design and analysis of electrical circuits, musical instruments, and other systems that involve periodic waves.

4. How does the Third Harmonic Frequency relate to other harmonics?

The third harmonic frequency is just one of many harmonics that can be present in a periodic wave. It is the third multiple of the fundamental frequency, while the second harmonic is the second multiple, and so on. The presence and strength of each harmonic can impact the overall properties of the wave.

5. Can the Third Harmonic Frequency be changed or manipulated?

Yes, the third harmonic frequency can be changed or manipulated through various methods such as adjusting the fundamental frequency, altering the properties of the medium through which the wave travels, or using filters to remove or amplify certain harmonics. This can be useful in applications such as signal processing and sound engineering.

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