Waht does standing wave with both ends open has 396hz mean?

[yjk91]

Homework Statement

A standing wave in a pipe with both ends open has a frequency of 396 Hz. The next higher harmonic has a frequency of 662 Hz.(a) Determine the fundamental frequency.


answer: 266 Hz

(b) How long is the pipe?
answer : 0.645 m

The Attempt at a Solution

i'm not sure how to solve this problem

f1 = v/(2L)

i thought of using algebraic equations for 396 and 662

396 hz = 2v/(2L)
662 hz = 3v/(2L)

but then it doesn't work
i am not sure...

i have the answers

266 hz = 343/ (2*0.645)
which works as the fundamental perfectly
but when i set 396 hz as 2nd harmonic and 662 hz as 3rd it doesn't work
and if the fundamental for open pipe both sides is 266 the next harmonic must be times 2 of f0, but it is not

thank you

 

[ehild]

This pipe is rather one end closed, I am afraid.

ehild

 

[yjk91]

i got it
the answer to the first question is 608 hz - 400hz = 208 hz

and the 2nd is 343/2/208 = 0.825m