Six Minute Solutions Problem 92

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DanHalen

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This problem must have come from another galaxy. I don't see a connection as to how they "integrated" to come up with 0.0001 m/min. Also how do they get 54 & 37.5 for the number of grid elements?

My assumption which is pretty far out is that they integrated 0.01 (or squared 0.01) to get 0.0001.

 
I have the 4th printing so it's probably not the same as what you have.

Problem 92

For a flow rate of 10,000 m3/d, what is the approximate overflow rate for a settling basin to achieve 80% efficiency? Results from a settling column test for the Type I suspension are shown in the illustration.

(I can't upload for some reason, keep getting annoying errors like "message is too short" and "this image cannot be loaded on this site.")

(A) 0.0085 m/min

(B) 0.011 m/min

© 0.015 m/min

(D) 0.02 m/min

Answer should be "C"

 
Posting this for DH. I'll try to work on it myself if time allows but this is a busy weekend and I am certainly no Environmental pro by any means. So, hopefully someone else can help.....

DH, I had to convert your file from pdf to jpg.

Capture.JPG

 
This problem must have come from another galaxy. I don't see a connection as to how they "integrated" to come up with 0.0001 m/min. Also how do they get 54 & 37.5 for the number of grid elements?

My assumption which is pretty far out is that they integrated 0.01 (or squared 0.01) to get 0.0001.




Okay DH, I finally had a chance to look at this problem. Like I said, I am no expert in Environmental but I think (keyword: think) I figured out the answers to your questions by slowly digesting the solution (like c_n mentioned, it's problem #96 in my old copy).

Okay, so the .0001 m/min is the area of one grid square. Each grid on the x-axis is .01 / 5 = .002 m/min wide. Each grid on the y-axis is .2 / 4 = .05 high. Thus, .002 m/min * .05 = .0001 m/min.

As for the 54 and the 37.5, these are the areas (the number of squares) under the curve for Trial 1 and Trial 2, respectively (although it seems to me they are counting partial squares as full squares).

Does this help?

 
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