Fluid Continuity Equation in different reference frame

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SUMMARY

The discussion centers on the Fluid Continuity Equation and its application in different reference frames. When a fluid with an area of 10 and a velocity of 10 increases its velocity to 20, the area decreases to 5. However, switching to a reference frame moving at a velocity of 1 in the opposite direction results in a perceived violation of the continuity equation. The key takeaway is that the area constriction is dependent on the reference frame of the tube through which the fluid flows, emphasizing the importance of understanding the derivation of the continuity equation.

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  • Basic principles of velocity and area relationships in fluid flow
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versine
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If I have fluid with area 10 and velocity 10, if the velocity increases to 20 the area will become 5. But if we switch to a reference frame moving at velocity 1 opposite this motion, then it would be 10 and 11 to 5 and 21, violating the continuity equation. What is wrong?
 
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If I understand what you ask correctly, the area is constricted because the fluid is moving through some tube. If that's the case, it's the velocity relative to the tube's reference frame that counts. You will see why if you follow the derivation of the continuity equation.
 
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