Finding the length of a string given f, F, λ and m

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Homework Help Overview

The discussion revolves around a physics assignment involving the properties of a vibrating string, specifically focusing on finding the length of the string given frequency, force, wavelength, and mass. The participants are exploring the relationships between these variables through relevant equations.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • The original poster attempts to apply a formula found online to rearrange and solve for the length of the string. Some participants question the validity of the equation used, particularly its connection to wave velocity. Others suggest alternative approaches based on the relationship between wavelength, frequency, and wave speed.

Discussion Status

The discussion is ongoing, with participants exploring different interpretations of the equations and their applicability. Some guidance has been offered regarding the use of wave speed to derive a simpler formula for length, but no consensus has been reached on the correctness of the initial formula.

Contextual Notes

Participants are working within the constraints of a homework assignment, which may limit the information available for discussion. There is uncertainty regarding the appropriateness of the formulas being used and their derivations.

romakarol
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Going through my physics assignment tonight, so that's 10 questions I'll be posting. Since I'm thoroughly hopeless at this subject most of my attempts will be based on my elite google-fu or trawling through lecture notes, bear with me and thanks!

1. Homework Statement
frequency (f)=160hz
Force (F)=150 Newtons
wavelength (λ)=0.40m
mass(m)=6 grams

find the length of a string with these properties

Homework Equations


f(λ)=sqrt [F/(m/L)]

found this formula and the statement "solve for L" for this exact question online.
I put the values in above, I believe I interpreted them right.

The Attempt at a Solution


It seemed a bit dodge to re-arrange, but i got L on it's own to be:
L= [F/(fλ ^2)]/m
(with values)
[150/(160x0.40)^2]/6=0.0061m...I have a feeling I may be off here XD.
 
Last edited by a moderator:
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romakarol said:
f(λ)=sqrt [F/(m/L)]
What is that equation? The right hand side (RHS) looks like the velocity of waves on a string...
 
I'm not sure, someone asked the same question as me on some website and that formula along with "solve for L" was the one-sentence reply. I used it because it seems to involve all the values listed in the question and can be used to find L. Is it incorrect?
 
Edit: see new post
 
Wait I found a simpler formula based on what you said:

upload_2016-4-8_2-10-7.png


I can get v since the wavelength and frequency is given (wavelength=v/frequency).

So if I re-arrange it to get L on its own, then L=[(m)(V^2)]/F, correct?
 
Last edited:
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