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How to find the tension in a guitar string? 
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#1
Oct811, 05:15 PM

P: 82

1. The problem statement, all variables and given/known data
The Bstring of a guitar is made of steel (density 7800 kg/m^3), is 63.5 cm long, and has diameter 0.406mm. The fundamental frequency is f = 247.0 Hz. Find the string tension. 2. Relevant equations F/A = YΔL/L 3. The attempt at a solution So I know we have the A, the Young's modulus, and the length. But there is no change in length! So there should be no tension/stress. I have no clue where to start, need some hints! Also how does frequency have anything to do with the tension? Is it just there to throw you off? Thanks. 


#2
Oct811, 05:21 PM

PF Gold
P: 7,363

Frequency has a lot to do with tension. The length from the nut to the bridge does not change, but the tension does. You have to adjust the tension in the string using the tuning machine. Higher tension = higher pitch.



#3
Oct811, 05:28 PM

P: 207

You should be supplied with the formula..
f = [itex]\frac{1}{2l}[/itex][itex]\sqrt{\frac{T}{\mu}}[/itex] f = frequency l = length T = tension [itex]\mu[/itex] = mass per unit length 


#4
Oct811, 05:29 PM

P: 82

How to find the tension in a guitar string?
Thanks though, now I know :P 


#5
Oct811, 08:42 PM

Sci Advisor
HW Helper
PF Gold
P: 4,119

for simple harmonic motion, [itex]F=k x[/itex], where x is the displacement from equilibrium...
Into Newton's Second Law, [itex]m\frac{d^2x}{dt^2}=kx[/itex], you get a differential equation whose solution [itex]x=A\cos(\omega t+\theta_0)[/itex] tells you what the angular frequency [itex]\omega[/itex] is (and what it depends and doesn't depend on). Can you use "relevant equation" here? 


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