laczlacylaci

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Jun 20, 2016
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upload_2016-8-26_11-33-47.png
From what I understand, there is open pipe (open at both ends) and closed pipe (open at only one end)
Open pipe: L=nlamdba/2
Closed pipe: L=nlambda/4

The q-stem states that the organ of corti is a closed pipe.
We know that as we go from base to apex in the cochlear, the frequency decreases. (we would use f=nv/4L)
As frequency decreases from b to a, we would expect L to increase, which matches with A. (linearly not exponentially, since there is no exponent in the formulas.)
In the key, it seems like by "closed organ", it meant both ends were closed, which I have never seen before. It then says that "closed organ"=closed-closed which is the same as open-open, so that is their reasoning for using the open-pipe formula (f=nv/2L) and not f=nv/4L
upload_2016-8-26_11-39-29.png

Either way, the length would increase with a decrease in frequency, but I just wanted to know if I was missing something regarding a closed-closed pipe being open-open pipe.

For now, all I know is:
open-open pipe: f=nv/2L (other terms: open pipe/organ, open at both ends...)
closed-open pipe: f=nv/4L (other terms: closed pipe/organ, closed at one end...)

tl;dr: why does closed organ mean closed at both ends, or use the open pipe equation?
 

theonlytycrane

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Mar 23, 2014
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A standing wave uses the same equation as an open-pipe. From the q-stem I saw standing wave and immediately thought of lambda = 2L / n. A lot of the MCAT physics is kind of silly. For me I just committed the equation to memory :)
 
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laczlacylaci

laczlacylaci

2+ Year Member
Jun 20, 2016
264
45
Cheese State
Status
Pre-Medical
A standing wave uses the same equation as an open-pipe. From the q-stem I saw standing wave and immediately thought of lambda = 2L / n. A lot of the MCAT physics is kind of silly. For me I just committed the equation to memory :)
Ok, so standing wave=open-pipe. Is there a specific name for closed pipe waves? lmao sorry for silly questions
 

theonlytycrane

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Mar 23, 2014
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Ok, so standing wave=open-pipe. Is there a specific name for closed pipe waves? lmao sorry for silly questions
haha it's a good question. The closed-pipe (no other name) will use the lambda = 4L / n where n is 1, 3, 5... (instead of 1, 2, 3... for open-pipe and standing waves).

Just remember that open-pipe means both ends are open and closed-pipe means that one end is closed.
 
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