Bernoulli Equation - Units Question

AI Thread Summary
The discussion centers on understanding the units in the Bernoulli equation, specifically how each term can be expressed in pressure units when divided by density (ρ). The equation is presented as P/ρ + V²/2 + gz = constant, leading to confusion about the units of the middle term. Clarification is provided that V represents velocity, not a higher power of meters, which resolves the unit discrepancies. The conversation also touches on the nature of Bernoulli's equation as a conservation of energy principle. Overall, the participants emphasize the importance of correctly interpreting units in fluid dynamics.
JJBladester
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Homework Statement



My book says that each term in the Bernoulli equation (when divided by ρ, has pressure units). I don't see how.

Homework Equations



The Bernoulli equation for steady, incompressible flow is:

\frac{P}{\rho}+\frac{V^{2}}{2}+gz=constant

The Attempt at a Solution



Multiplying the Bernoulli equation by density (ρ), we get:

P+\rho\frac{V^{2}}{2}+\rho gz=constant

ρ = kg/m3 units

V2=m6 units

ρV2=kg*m3 units

How does the middle term in the Bernoulli equation with the units listed above count as having pressure units?

Pressure = Force/Area = Newtons/m2= \frac{\frac{kg\cdot m}{s^2}}{m^2}=\frac{kg}{m\cdot s^2}
 
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Hi JJBladester! :smile:
JJBladester said:
V2=m6 units

Nooo :redface:

V is velocity! :biggrin:

(btw, Bernouilli's equation is essentially a conservation of energy equation, which is why you get a sort-of mv2/2 term :wink:)
 
tiny-tim said:
Hi JJBladester! :smile:
Nooo :redface:

V is velocity! :biggrin:

I need more coffee. Wow, I wish I could unpost that last post.

Thanks for the reply, though. It makes a lot of sense now.
 
JJBladester said:
I need more coffee.

nooo, you need more sleep! :zzz: :wink:
 
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