Pressure flux?

[vlad777]

I just want to inquire if it is correct to say that:
force is pressure flux ?

Pressure acts at every point of surface and force is pressure times that surface.
This is analogical to electric and magnetic flux.

Many thanks.

 

[3v0]

I just want to inquire if it is correct to say that:
force is pressure flux ?

Pressure acts at every point of surface and force is pressure times that surface.
This is analogical to electric and magnetic flux.

Many thanks.

Not 100% pure but if one is talking about "Flux as flow rate per unit area" then one has to have flow rather then potential aka pressure.

 

[vlad777]

I never realized that word flux is related to word flow. o_o

Edit:
So electric and magnetic field pass trough surface and pressure doesn't
and also pressure is not a field.
So it is not correct / doesn't make sense?

 

[MrAl]

Hi,

Flux implies that something is moving, real or possibly not real.

A field is nothing more than a region where we can assign at least one value to every point in the space of that field. So if we had a closed stainless steel cube filled completely with water (the water with some dissolved oxygen) under some pressure we could describe every point inside that cube as having a certain constant pressure. And as we strike the cube on one side with a hammer there would be created a pressure wave starting from that one side to the other (at least) and that would mean we would have to assign higher values to points on the side that was struck at least during the first moments of impact.

 

[vlad777]

I am trying to imagine this cube with imaginary surface cut trough it, but pressure along that surface wouldn't be a vector.
(PS maybe you don't need dissolved gas, just the cube sides have to put force to water)

 

[MrAl]

<snip>
and also pressure is not a field.

Hi again,

Your post stated that you were comparing a "field", not a "vector field". So i replied with an example of a field, not a vector field.

If the water does not contain dissolved gas then it is usually considered incompressible, and that just means that we cant have a pressure wave that starts out large and graduates to a lower pressure on the other side of the cube. I wanted to make it more interesting otherwise we'd just have a cube that got pushed in on one side (concave) and pushed out on the other side (convex) taking no time to do that, which isnt as interesting as when we push it in on one side and it takes some time for the other side to start to bulge out. Using this simple example we might also say that the sides parallel to the direction of the force are also completely rigid so that only those four sides do not bulge but just the other side normal to the direction of the force. This makes it a little simpler but still interesting.

 

[vlad777]

So electric or magnetic flux is dot product and force is scaled vector (pressure scalar times surface scalar times surface normal vector).

 

[vlad777]

MrAl.

What you are talking about is a sound wave.
Solids are also considered incompressible but still speed of sound trough them is not instantaneous.