- #1

Ethan_Tab

- 57

- 2

## Homework Statement

Two pipes, Identical in length and closed at one end are producing notes. You are very, very annoyed because the notes are creating an audible beat frequency of 20Hz. If one pipe is producing a note at 10Hz and the temperature is 15C (which correlates to a speed of sound of 340.39m/s), what is the length of the two pipes?

## Homework Equations

Beat frequency= abs(ƒ_2-ƒ_1)

L(n)=[(2n-1)/4]λ --- (length as a function of the harmonic)

v=λƒ

v(t)=331.4+0.606T --- (velocity as a function of temperature)

T=1/f --- where T= period

## The Attempt at a Solution

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Since we can't have negative beat frequencies we know that the second pipe is creating a 30Hz sound.

λ_2=340.39/30=11.35meters (second pipe)

and

λ_1=340.39/10=34.04 meters (first pipe)

We also know that for a closed pipe, the closed end must have a node while the open end must have an antinode. But since we don't know the harmonic, there's not much we can do with that information.

Any ideas?