Bernoulli Principle: Homework Solution

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The discussion centers on applying the Bernoulli Principle to a homework problem involving water flow through a pipe. The flow rate is given as 96 L/min, with a pressure of 80 kPa at the lower end and height differences of 10 m and 13 m at both ends. Participants express challenges in using the continuity equation due to the lack of diameter information for area calculations. There is confusion regarding the application of the Bernoulli equation and the treatment of pressure terms, with some suggesting that areas at both ends are equal. The conversation highlights the need for clarity in the problem statement and proper application of fluid dynamics principles.
srollin6
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Homework Statement



Water Flows upward throw the pipe shown in the diagram at 96 L/Min. If the pressure at the lower end is 80kPa, find the velocity of the water is at both ends and the pressure at the upper end. Assume that the density of water remains constant throughout the tube and that h1= 10 m and h2 = 13m

Homework Equations


P1+ 1/2 ρv^2+gy1=P2+1/2ρv2^2+gy2

Continuity Equ:
A1V1=A2V2
(Tried to use this equation to hep me find the velocity but given their is no diameter or radius given to find the are it was a waste of time)

The Attempt at a Solution


volume flow rate up the pipe:
96L/min (1.0X10^3 cm^3/ 1.00L)(1.00m/100cm)^3(1.00min/60sec) = 1.6x10^3 m^3/s


Attempt to tried to use the Continuity Equation as substitution for one of the velocities:


A1V1=A2V2

V2(A2/A1)= V1

Substituting V1 in the Bernoulli Equation:
P1+1/2ρ(V2(A2/A1))^2+ρgy1=P2+1/2ρv2^2+gy2

2g(y^2-y1)=v2[1-(A2/A1)]

sqrt(2gh)/sqrt(1-(A2/A1)^2) =v2



Any help or guidance will be appreciated. Thank you.
 
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srollin6 said:
... find the velocity of the water is at both ends ...
Something missing in the problem statement?
P1+ 1/2 ρv12+gy1=P2+1/2ρv22+gy2
Should be ρgy1, ρgy2, yes?
Continuity Equ:
A1V1=A2V2
(Tried to use this equation to hep me find the velocity but given their is no diameter or radius given to find the are it was a waste of time)
It doesn't mention any change in area, so presumably A1=A2.
Substituting V1 in the Bernoulli Equation:
P1+1/2ρ(V2(A2/A1))2+ρgy1=P2+1/2ρv22+gy2

2g(y^2-y1)=v2[1-(A2/A1)]
How do you get that last equation from the preceding one? What happened to P1 and P2?
 
The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

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