Bernoulli Principle: Homework Solution

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SUMMARY

The discussion focuses on solving a fluid dynamics problem using the Bernoulli Principle and the Continuity Equation. The problem involves water flowing upward through a pipe at a rate of 96 L/min, with a pressure of 80 kPa at the lower end and height differences of 10 m and 13 m at the two ends. Participants clarify the application of the Bernoulli Equation and the Continuity Equation, emphasizing the need for consistent area assumptions and the correct substitution of velocities to find the water's velocity at both ends.

PREREQUISITES
  • Understanding of Bernoulli's Equation
  • Knowledge of the Continuity Equation
  • Familiarity with fluid dynamics concepts
  • Basic algebra for solving equations
NEXT STEPS
  • Study the derivation and application of Bernoulli's Equation in fluid mechanics
  • Learn about the Continuity Equation and its implications in flow rate calculations
  • Explore the effects of varying pipe diameters on fluid velocity
  • Investigate real-world applications of the Bernoulli Principle in engineering
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Students studying fluid dynamics, engineers working with fluid systems, and anyone interested in applying the Bernoulli Principle to practical problems.

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?
 

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