Pressure Difference: Is the Solution Wrong?

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Homework Help Overview

The discussion revolves around the application of Bernoulli's equation in a problem concerning pressure difference and height between two points, A and B. Participants are questioning the correctness of a provided solution and the interpretation of the equation.

Discussion Character

  • Assumption checking, Problem interpretation, Exploratory

Approaches and Questions Raised

  • Participants are examining the algebraic manipulation of Bernoulli's equation and questioning the signs used in the height difference. There is a focus on whether the heights of points A and B are correctly interpreted in the context of fluid flow direction.

Discussion Status

The discussion is active, with participants providing feedback on algebraic checks and expressing agreement on certain interpretations. There is an exploration of the implications of height differences on fluid flow direction, but no consensus has been reached regarding the correctness of the original solution.

Contextual Notes

Participants note that point A is stated to be higher than point B, which influences the interpretation of the pressure difference. There is also mention of the Reynolds number in relation to the flow type, indicating additional considerations in the problem context.

foo9008
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Homework Statement


is the solution given wrong ? from the bernoulli's equation , (PA-PB) / ρg = hf + ZB - ZA , am i right ? P/s : the Velocity at A and B are the same , so they cancel each other ... but in the solution , the author gave (PA-PB) / ρg = hf + ZA - ZB which is 18.27 +40 , IMO , it should be 18.27-40 , am i right ?

Homework Equations

The Attempt at a Solution

 

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Check your algebra.
 
ya , what's wrong with it ?
 
Chestermiller said:
Check your algebra.
the question gave point A is 40m higher than B ...
 
Yes. I agree with you.
 
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Chestermiller said:
Yes. I agree with you.
since 18.27 - 40 has negative value , so the water should flow from B to A ?
 
foo9008 said:
since 18.27 - 40 has negative value , so the water should flow from B to A ?
They probably meant to say that B is higher than A.

By the way, did you check the Reynolds number to see if the flow really would be laminar?
 

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