Calculating Velocity of Water in a Circular Pipe

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Homework Help Overview

The problem involves calculating the velocity of water flowing through a circular pipe when the diameter decreases. The context is fluid dynamics, specifically applying the principle of conservation of mass in incompressible flow.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss using the equation of continuity (AV=AV) to relate the areas and velocities before and after the diameter change. There are attempts to express area in terms of diameter and questions about the correctness of the initial setup.

Discussion Status

Some participants have suggested rewriting the area in terms of diameter and have noted the importance of recognizing the area of a circle. Others propose calculating the volumetric flow rate as an alternative approach. The discussion is ongoing with various methods being explored.

Contextual Notes

Participants are working under the assumption that the flow is steady and incompressible, and there is a focus on the relationship between area and velocity in the context of a circular pipe.

kitty9035
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Homework Statement


Water is flowing at 1 m/s in a circular pipe. If the diameter of the pipe decreases to four-ninth its former value, what is the velocity fo the water downstream?


Homework Equations



AV=AV

3. The Attempt at a Solution [/b
(Area1)(Velocity1)=(Area2)(Velocity2)
then...
(A1)(1 m/s)=(4/9)A1(V2) ?
or
A1=(4/9)(V2)

Is that right what would u do next??
 
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Rewrite the area in terms of its diameter, and then try again.
 
Indeed, remember the area for a circle? *circular* being the key word =).
 
couldn't you just with what your given calculate the volumetric flow rate then, then apply Q = AV to get the velocity in the second pipe.. that's how I would do it
 
A1V1 = A2V2, since the density is uniform/incompressible.

You could do as you say, but then you'd have the equation:
A1 * (delta L1) / delta t = A2 * (delta L2) / delta t

A1V1 = A2V2 is a better one to use; well more "simple" one.
 

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