(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A 4.0g string of 0.67m length is vibrating at 300Hz in the third harmonic. The speed of sound in the air is 344 m/s. What is the tension in the string in SI units.

A) 110

B) 88

C) 69

D) 130

E) 150

2. Relevant equations

//frequency is equal to velocity over wavelength

f = v/lambda

3. The attempt at a solution

So, f sub n = nf sub 1, the fundamental frequency. That means that I can rewrite this using the frequency equation as...

100*2*L*sqrt(m/L) = sqrt(T)

=> 100*2*0.67*.0773 = sqrt(T)

=> 10.35 = sqrt(T)

=> (10.35)^2 = T

=> T = 107.2

107.2 is closest to 110, which is choice A, but it isn't exact and I didn't use the speed of sound in the air quantity for anything. I'm not sure if I did this problem correctly or not? Can anybody help?

Thanks in advance.

**Physics Forums | Science Articles, Homework Help, Discussion**

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Tension in a vibrating string at a given frequency

**Physics Forums | Science Articles, Homework Help, Discussion**