Vibration and Frequency Questions

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Homework Help Overview

The discussion revolves around problems related to vibrations and frequencies, specifically involving a bungee cord and seismic waves. Participants are exploring concepts of linear density, wave properties, and the behavior of sound waves in different mediums.

Discussion Character

  • Exploratory, Conceptual clarification, Problem interpretation

Approaches and Questions Raised

  • One participant calculates the linear density of a bungee cord but expresses uncertainty about the next steps. Another participant discusses the relationship between mass, velocity, and length in the context of sound waves, indicating an exploration of modal frequencies. A request for clarification on two questions suggests a need for further understanding of the topics.

Discussion Status

The discussion is ongoing, with participants sharing their attempts and methods. Some guidance has been offered regarding different approaches to the problems, but there is no explicit consensus or resolution yet.

Contextual Notes

Participants mention that the topics are new to them, indicating a potential gap in foundational knowledge. There is also a reference to homework constraints, as participants seek assistance without providing complete solutions.

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Homework Statement


A 75 g bungee cord has an equilibrium length of 1.20 m. The cord is stretched to a length of 1.80 m, then vibrated at 20 Hz. This produces a standing wave with two antinodes.

Homework Equations


Linear Density = m/L

The Attempt at a Solution


So far I've only found the linear density to be 0.0626kg/m. I'm stuck after this and have no clue on where to start next.

Homework Statement


Earthquakes are essentially sound waves traveling through the earth. They are called seismic waves. Because the Earth is solid, it can support both longitudinal and transverse seismic waves. These travel at different speeds. The speed of longitudinal waves, called P waves, is 8000m/s . Transverse waves, called S waves, travel at a slower 4500m/s . A seismograph records the two waves from a distant earthquake.

Homework Equations



Not sure.

The Attempt at a Solution


I'm not exactly sure on how to start this. This topic is very new to me. Can someone get me started?
 
Last edited:
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So what I did for this question is, attempt to plug in values for 'm' so, for example

390 = m v/2L
390 = 1 343/2L

and find length that way,
it turned out that 390 represents the 3rd modal where (m = 3). Velocity is of course 343 m/s because sound will travel thorugh the tube which is open-open.
 
oh yeah, i got that question just after I posted. Thanks for explaining a different method though. I used a different way to find the length of the tube.
 
um can anyone fill me in on these two questions?
 

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