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nn3568

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## Homework Statement

The length of a string is 1440 cm. The

string is held fixed at each end. The string

vibrates in eight sections; i.e., the string has

eight antinodes, and the string vibrates at

150 Hz.

What is the fundamental frequency? Answer

in units of Hz.

## Homework Equations

f = nv / 2L frequency = (# antinodes)(velocity) / (2 * length)

## The Attempt at a Solution

I already found the wavelength which is 3.6 m. I got that by substituting nv/2L for f into the equation v=λf (velocity = wavelength*frequency). Then I followed the above frequency formula:

v=λf

v=(3.6 m)(150 Hz) = 540 m/s

f = nv / 2L

f = (8)(540 m/s) / (2*14.4 m) = 150 Hz

My online HW said it was wrong. So I tried again.

f = (2)(540 m/s) / (2*14.4 m) = 37.5 Hz

I used two because it said that fundamental frequency is the lowest frequency and you can use the first harmonic or something. Didn't really understand it. But the two is because the 1st harmonic has 2 antinodes.

I am so confused and I have no clue what I am doing! Please help <:S

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