PHYSICS - VERY HARD, CONFUSING QUESTION HELP <span title="PLEASE!!!!!!!!!!!!!!!!!!!!!!!!!!!1?">PLEASE!!!!!!!!!!!!!!!!!!!...</span>

Question

An open-open organ pipe is 70.5 cm long. An open-closed pipe has a fundamental frequency equal to the third harmonic of the open-open pipe.

How long is the open-closed pipe?

Answer 1

Find the Fundamental frequency:

fund frequ. = the third harmonic of the open open pipe

This is the tricky part:

The 3rd harmonic of an open open pipe is 3X fundamental frequency

O-O Fund Frequ. = 340 (the speed of sound in air) / 2L

340 / (2*.705 m) = 241Hz &lt;-- fund frequ.

3 * 241 = 723 Hz &lt;-- Frequ. @ 3rd Harmonic

723Hz is told be also be the frequency at the fundamental harmonic of the Open-Closed Pipe.

v= f * wavelength

340 = 741 * wavelength

wavelength = 0.459 m or 45.9 cm @ fund frequ.

At fundamental frequency of Open / Closed pipe the length is 1/4 of the wavelength

L = wavelength / 4

L = 45.9 /4 = 11.475 cm

I think i&#039;m right