Bernoulli's principle- fluids ?

AI Thread Summary
Bernoulli's principle is discussed in the context of fluid dynamics and homework equations related to it. The user struggles with applying the equations correctly, particularly in manipulating the velocity terms and understanding the relationship between pressure and velocity. A suggestion is made to simplify the Bernoulli equation by canceling ambient pressure values and focusing on the change in height and velocity. The conversation emphasizes the importance of expressing velocity in terms of mass flow and area to solve the problem. Ultimately, the user finds clarity and expresses gratitude for the guidance received.
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bernoulli's principle- fluids...?

Homework Statement



http://img30.imageshack.us/img30/4119/45086777.jpg

Homework Equations



A1V1=A2V2
P2+1/2pv1^2 = p1+1/2pv2^2
P+1/2mv^2 + pgy = constant

The Attempt at a Solution



V2=A1*V1/A2
1/2*p*A1^2*V1^2*p*g*h/A2^2=1/2pv1^2
2*g*h*A1^2V1^2/ A2^2=V1^2
V1=A1*V1gh/A2and I am stuck... i end up canceling the V1 >:(
 
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GOOOOD!
i've tried like 10 different things and i can't get it..
 


Do you think this equation correct? "P2+1/2pv1^2 = p1+1/2pv2^2"

ehild
 


Write out your full Bernoulli's equation:
<br /> P + \frac{\rho V^2}{2} + \rho g z = c<br />
The pressure values are both places are ambient so they cancel. You have the change in distance z2 - z1, so the only thing left is to find the velocity. Unfortunately, you don't have this.

So, it will be useful to write our your velocity term as a function of mass flow and area. You know that mass flow is equal, so you will eventually be left with simply area.
 


i got it!
thanks ! :D
 
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