- #1
FADFAD1
Does Pressure multiplied by volume multiplied by volumetric flow rate equal Force?
Does Pressure Multiplied by Volume and Volumetric Flow Rate Equal Force?
- Context: Undergrad
- Thread starter FADFAD1
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Discussion Overview
The discussion revolves around the relationship between pressure, volume, volumetric flow rate, and force. Participants explore the validity of the equation that suggests a multiplication of these terms results in force, examining the underlying principles and units involved.
Discussion Character
- Exploratory
- Technical explanation
- Debate/contested
Main Points Raised
- Some participants question whether pressure multiplied by volume and volumetric flow rate equals force, seeking clarification on the units involved.
- One participant calculates the units as Nm4/s, indicating a potential inconsistency in the equation.
- Another participant asks for a description of each term, suggesting there may be an extra volume term included in the equation.
- A participant presents an equation involving pressure, area, incremental length, and volumetric flow rate, raising concerns about potential redundancy in terms used.
- Another participant emphasizes that in the context of a flowing fluid, multiple terms contribute to force, and suggests that pressure effects and momentum change effects should be treated separately rather than combined into a single term.
Areas of Agreement / Disagreement
Participants express differing views on the validity of the proposed equation and the interpretation of the terms involved. There is no consensus on whether the equation accurately represents the relationship between the variables.
Contextual Notes
Participants highlight potential issues with unit consistency and the inclusion of multiple physical effects in a single equation, but do not resolve these concerns.
- #2
berkeman
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Welcome to the PF.FADFAD1 said:
What do the units work out as?
- #3
FADFAD1
N/m2 x m3 x m3/s so Nm4/sberkeman said:Welcome to the PF.
What do the units work out as?
- #4
berkeman
Admin
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Can you describe each term? It looks like you have an extra m^3 in there...?FADFAD1 said:
- #5
FADFAD1
the equation is pAdeltaL * dv/dt
so pressure times volume times change in length time volumetric flow rate
so pressure times volume times change in length time volumetric flow rate
- #6
jbriggs444
Science Advisor
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The equation has pressure p.FADFAD1 said:
Area A
Incremental length delta L
Incremental volume dv/dt
Are you not double-dipping? You have both area times incremental length and incremental volume?
- #7
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In terms of a flowing fluid, there are multiple terms that contribute to force. One of them happens to be from pressure and looks like ##pA## (or rather ##\int p\;dA##). Your term has a bunch of extra stuff in it. My suspicion is that you are trying to combine too many physical effects into a single term rather than separating their contributions. Specifically, pressure effects and momentum change effects must be treated separately (though there are relationships between some of those variables).
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