Unit conversion


by bprku
Tags: conversion, unit
bprku
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#1
May8-09, 04:13 AM
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Hi,

I ma having problem, can anyone help me converting ""individual/liter to individual/square meter"

for example 20 fish/L = ?? fish /m2
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CompuChip
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#2
May8-09, 05:30 AM
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Well, liter is a measure of volume (1 liter is 1 dm3), and square meter is a measure of area. So you are still missing some information.
bprku
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#3
May8-09, 08:32 AM
P: 2
well, I dont agree with you since this is the measure uses in biology. let me give you answer, if you go to a lake with a 1 liter cylinder and catch 20 Daphnia. so its clear that you have 20 daphnia/L. Now the question is how many daphnia will be in one square meter. if you think this isa stupid question real some articles publishes in aquatic biology"http://www3.interscience.wiley.com/cgi-bin/fulltext/119081299/PDFSTART"

symbolipoint
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#4
May8-09, 12:20 PM
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Unit conversion


Quote Quote by bprku View Post
Hi,

I ma having problem, can anyone help me converting ""individual/liter to individual/square meter"

for example 20 fish/L = ?? fish /m2
In the strictest of theoretical sense, you cannot make that conversion. Do you have a particular practical application which would be simpler if you were to make such a conversion?

The reason why in theory you can not make the conversion is that Liter is a unit of volume (or space), and square meter is a unit of area (or surface). The DIMENSIONs do not match.

Do you have a situation in which you may safely ignore one of the physical measurements in order to use area instead of volume?
CompuChip
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#5
May8-09, 12:42 PM
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I cannot access your link, even through my institutions' website.
Also I do not think it is a stupid question, I just think it is a meaningless question until you give us the "hidden" information.

Here's an analogous question for you: Suppose one bucket of paint suffices for 40 square meters, and my house is 20 meters long. How many buckets of paint do I need to paint the outside wall?
berkeman
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#6
May8-09, 12:55 PM
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Quote Quote by bprku View Post
well, I dont agree with you since this is the measure uses in biology. let me give you answer, if you go to a lake with a 1 liter cylinder and catch 20 Daphnia. so its clear that you have 20 daphnia/L. Now the question is how many daphnia will be in one square meter. if you think this isa stupid question real some articles publishes in aquatic biology"http://www3.interscience.wiley.com/cgi-bin/fulltext/119081299/PDFSTART"
Your link appears to be to a site that requires joining or paying to view whatever articles you are referring to.

As others have stated, your question is not answerable without a bit more information. Your example of a liter bottle with 20 items in it does not help. When you say "per square meter", are you perhaps thinking of looking down into the water, and seeing fish below a 1 square meter grid? If you have a volume density of something, you will need the depth of the water to know how many of whatever is below a 1 square meter grid.
TVP45
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#7
May8-09, 01:47 PM
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I should guess he is referring to ponds where fish density was once measured as fish per acre of bottom. I suppose he is now referring to smaller ponds (or perhaps a more manageable number) when he uses fish per square meter. There would be no conversion applicable for ponds since depth doesn't have the same meaning as in lakes. You could use an average depth to get the liters, but I think that might be misleading.
russ_watters
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#8
May8-09, 02:55 PM
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It is also possible that it is just an error and s/he is actually looking for fish per cubic meter...
TVP45
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#9
May8-09, 04:31 PM
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Is that blue fish or red fish?
CompuChip
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#10
May8-09, 05:01 PM
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Quote Quote by TVP45 View Post
Is that blue fish or red fish?
You're mistaking fish for pills.
Anyway, we're going off-topic here (time Mr Smith comes along and fixes that).
TVP45
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#11
May9-09, 06:01 AM
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Thinking about this a bit, I have a suggestion as to what the situation might be. I used to hang around a fish culture station (don't even think of mentioning Handel ) and they had two common measures: fish density in ponds (that's the fish per acre number which is easily converted to fish per square meter) which is counted by taking some sample area and running the fish through an outlet; and carrying capacity which is a measure of lakes and flowing streams to support fish in pounds per cubic foot. You don't convert from one number to the other; rather you factor them together to get some average weight. Likely, for a given body of water you could probably devise a calibration chart to do that conversion but it would vary from body to body. You might look into farm fish culture to see if they use such a measure.


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