Standing Sound Waves: Wavelengths in 121 cm Tube - SOLVED

[dals2002]

[SOLVED] Standing Sound Waves

What are the three longest wavelengths for standing sound waves in a 121 cm long tube that is (a) open at both ends and (b) open at one end, closed at the other?


the wavelength equation that i used for open-open was \lambda= 2L/m; where m is the number of modes (m=1,2,3,4...)

and then for open-closed \lambda= 4L/m; where m is the number of modes (m=1,3,5,7...)

so i have the length, but the one question that i have about this problem is could i start with the lowest number of modes, but if that is true then why ask for the three longest wavelength, so i am kind of lost if anyone could give me a clue on what to do

thanks in advance

 

[Snazzy]

The three longest wavelengths correspond to the three lowest modes.

 

[dals2002]

oh ok, that was exactly what i thought it was thanks