What is meant by pressure being a momentum flux?

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SUMMARY

The discussion centers on the interpretation of pressure as a momentum flux, specifically through the equation: pressure = (1/3) * number density * volume * momentum. Participants clarify that pressure is defined as force per unit area (N/m²) and that momentum flux is expressed as (kg·m/s) / (m²·s). The conversation highlights the need for consistency in units, suggesting that "volume" in the equation should likely be "velocity" to maintain dimensional accuracy.

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  • Understanding of basic physics concepts such as pressure and momentum.
  • Familiarity with units of measurement in physics, particularly N/m² and kg·m/s.
  • Knowledge of the equation of state in thermodynamics.
  • Basic grasp of fluid dynamics and momentum transfer.
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clumps tim
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hi, I have been working on equation of state and one of my article says pressure is a momentum flux. what is the physical meaning of this? they have written it as

pressure =(1/3) *number density*volume*momentum

please explain me the expression

regards
 
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I'm sorry you are not generating any responses at the moment. Is there any additional information you can share with us? Any new findings?
 
no not yet, how is pressure a momentum flux?
 
A flux of something has units of something per m2 per second: something / (m2·s).

So momentum flux would be (kg·m/s) / (m2·s). I'll let you simplify it.

Pressure is force per unit area: N/m2. Expand the Newtons into basic units, simplify, and compare with the units of momentum flux.
 
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clumps tim said:
no not yet, how is pressure a momentum flux?

force is a momentum transfer rate:
momentum / time

pressure is force density :
force / area
or:
momentum / time / area
 
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clumps tim said:
pressure =(1/3) *number density*volume*momentum

Assuming that "number density" means something like "molecules per m3" and "momentum" means "momentum per molecule", the units are not consistent in this equation. I think "volume" should be "velocity", i.e. you have mis-interpreted a "v" in the original equation.
 
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thank u all.
 

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