Bernoulli Equation - Units Question

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SUMMARY

The discussion centers on the Bernoulli equation for steady, incompressible flow, specifically addressing the units of each term when divided by density (ρ). The equation is expressed as P/ρ + V²/2 + gz = constant, where P represents pressure, V is velocity, and g is gravitational acceleration. The confusion arises regarding how the term ρV²/2 maintains pressure units. Clarification is provided that V is indeed velocity, reinforcing the equation's interpretation as a conservation of energy principle.

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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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