# What is meant by pressure being a momentum flux?

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

regards

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?

jtbell
Mentor
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.

• GaryWilbourn
A.T.
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

• GaryWilbourn and clumps tim
jtbell
Mentor
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.

• 1 person
thank u all.