TPR PHYSICS (frequency) # 308 pg 38

[crazy person]

Advertisement - Members don't see this ad

Hey guys , with this question :

308 ) In a given medium with fixed boundaries, the longest wavelength that will set up a standing wave is 4m. If waves propagate through the medium at 8m/s, what is the LOWEST possible frequency associated with a standing wave within this medium ?


I know that the lowest frequency is the longest wavelength which we can use immediately the equation f= v/lamba which gives 2 Hz.

But my question is, since its fixed with boundaries in a standing wave and its asking for the frequency, shouldn't we use this equation: f = nv/ 2L , which gives me 1 Hz, which is not the answer obviously. But I want to know why can't we use this formula ?

Thanks guys !!!

 

[dudewheresmymd]

you made a math error. you can use that formula.

lambda= 2L/n (n=1, and lambda = 4) 4/2 =2 m is the length of the pipe

plug in L=2 into fn=nv/2L

f=(1)*(8)/(2*2) = 2 hz

 

[crazy person]

omg. now I see it. Thanks !