Just had a Test and I could not get this one

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Homework Help Overview

The discussion revolves around the interference of two sinusoidal waves creating a standing wave, with a specific focus on determining the original wavelength based on the distance between nodes. The problem includes a frequency of 100 Hz.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants explore the relationship between nodes and wavelengths, questioning how many wavelengths fit between the 2nd and 5th nodes. There is uncertainty about how to utilize the frequency and the distance provided in the problem.

Discussion Status

The conversation reflects a mix of attempts to clarify the relationship between nodes and wavelength, with some participants expressing confusion about the relevance of the frequency. There is no explicit consensus on the correct approach or solution yet, but participants are engaging with the problem and sharing thoughts.

Contextual Notes

Participants note the absence of certain information, such as wave speed and properties of the medium, which are necessary to fully resolve the problem. The role of the frequency in the context of the problem is also questioned.

Saladsamurai
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It was only worth 5 points so I just guessed.

Two sinusoidal waves interfere with each other to produce a Standing wave. The distance between the 2nd and 5th node is 60cm. What was the original wavelength of the original waves?

Oh yeah, and f=100Hz.

Where do I start on this one. I know f=nv/2L and V=lambda*f

um...I guess I am missing whatever the key concept is here to establish the correct relationship.

Any ideas?

Casey
 
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The nodes are where the string (or whatever) is not moving. There are how many wavelengths in the 3 nodes as you go from the 2nd to the 5th node?
 
berkeman said:
The nodes are where the string (or whatever) is not moving. There are how many wavelengths in the 3 nodes as you go from the 2nd to the 5th node?

1.5 ? I am not sure what to do with this number. ...60/1.5=40cm?

Casey
 
Last edited:
But seriously...now what?
 
Saladsamurai said:
1.5 ? I am not sure what to do with this number. ...60/1.5=40cm?

Casey

That would be what I would put down. Do you know if it is correct?
 
berkeman said:
That would be what I would put down. Do you know if it is correct?

I don't know. So is the 100Hz just there to mess with me?
 
Saladsamurai said:
I don't know. So is the 100Hz just there to mess with me?

To test your thinking (aka mess with you). The 100Hz is no help in determining the wavelength unless you have what other two pieces of information about the string?
 
berkeman said:
To test your thinking (aka mess with you). The 100Hz is no help in determining the wavelength unless you have what other two pieces of information about the string?

If I had wave speed V... It did not say it was a string so in general I would have needed some representitive of its elasticity (tension or bulk modulus) and its inertia (linear or volumetric density) since [tex]V=\sqrt\frac{elasticity}{inertial}[/tex]

Casey
 
Saladsamurai said:
1.5 ? I am not sure what to do with this number. ...60/1.5=40cm?

Casey

I agree too.

the distance between two adjacent nodes is half the wavelength of the two waves combining to give a standing wave pattern.
 

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