What is meant by pressure being a momentum flux?

  • Thread starter 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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  • #2
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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?
 
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no not yet, how is pressure a momentum flux?
 
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jtbell
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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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  • #5
A.T.
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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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jtbell
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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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  • #7
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thank u all.
 

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