Force Acting on Area: ucos(theta)dA vs usin(theta)dA

Thread starter foo9008
Start date Mar 15, 2016
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Area Force

AI Thread Summary

The discussion centers on the confusion regarding the expression for volume flow rate through an area element, specifically whether to use ucos(theta)dA or usin(theta)dA. It is clarified that dA lies in the yz plane, which influences the direction of the flow velocity component. The author argues that if u' = ucos(theta), it aligns with dA, suggesting that the correct term should indeed be ucos(theta)dA. The distinction between the components is crucial for accurately calculating flow rates. Understanding the orientation of dA in relation to the flow direction is essential for proper application of the equations.

Mar 15, 2016

foo9008

Homework Statement

dA lies on x and y aixs , right ? the author gave that the volume flow rate thru element A is ucos(theta)dA , why not
usin(theta)dA ? if u ' = ucos(theta) , it will become parallel to dA , right ? since u' will be parallel to x-axis...

Homework Equations

The Attempt at a Solution

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Mar 15, 2016

BvU

Science Advisor

Homework Helper

dA is in the yz plane

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