Water Distribution 1
Water Water DistributionDistribution
Water Distribution 2
Introductory QuestionIntroductory Question
Water enters your home plumbing Water enters your home plumbing at ground level. Where will you get at ground level. Where will you get the strongest spray from a shower?the strongest spray from a shower?
A.A. In the ground floor showerIn the ground floor shower
B.B. In the basement showerIn the basement shower
C.C. In the second floor showerIn the second floor shower
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Observations aboutObservations aboutWater DistributionWater Distribution
Water is pressurized in the pipesWater is pressurized in the pipes Higher pressure water sprays harderHigher pressure water sprays harder Higher pressure water sprays higherHigher pressure water sprays higher Water is often stored up high in Water is often stored up high in
water towerswater towers
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4 Questions about Water 4 Questions about Water Distr.Distr.
Why does water move through level Why does water move through level pipes?pipes?
How can you produce pressurized How can you produce pressurized water?water?
Where does the work you do Where does the work you do pumping water go?pumping water go?
As water flows, what happens to its As water flows, what happens to its energy?energy?
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Question 1Question 1
Why does water move through level Why does water move through level pipes?pipes? Can water in a level pipe move without Can water in a level pipe move without
a push?a push? How does water in a level pipe respond How does water in a level pipe respond
to a push?to a push? How do you push on water in a level How do you push on water in a level
pipe?pipe?
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How Water Moves How Water Moves (no (no gravity)gravity)
Water, like all fluids, obeys Newton’s Water, like all fluids, obeys Newton’s lawslaws When water experiences zero net force, it When water experiences zero net force, it
coastscoasts When water experiences a net force, it When water experiences a net force, it
acceleratesaccelerates Pressure imbalances exert net forces on Pressure imbalances exert net forces on
waterwater Water accelerates toward lower pressureWater accelerates toward lower pressure
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Question 2Question 2
How can you produce pressurized How can you produce pressurized water?water? How can you create pressure?How can you create pressure? How can deliver pressurized water to a How can deliver pressurized water to a
pipe?pipe? Why does pumping water require such Why does pumping water require such
effort?effort?
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Pressurizing WaterPressurizing Water
To pressurize water, confine it and To pressurize water, confine it and squeezesqueeze As you push inward on the water,As you push inward on the water, it pushes outward on you (Newton’s it pushes outward on you (Newton’s
third law).third law). water’s outward push is produced by its water’s outward push is produced by its
pressurepressure the water’s pressure rises as you the water’s pressure rises as you
squeeze it hardersqueeze it harder
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Pumping Water Pumping Water (no gravity)(no gravity)
To deliver pressurized water to a To deliver pressurized water to a pipe,pipe, squeeze water to increase its pressuresqueeze water to increase its pressure until that pressure exceeds the pressure until that pressure exceeds the pressure
in the pipe.in the pipe. The water will then accelerate toward The water will then accelerate toward
the pipethe pipe and pressurized water will flow into the and pressurized water will flow into the
pipe!pipe!
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Pumping Requires WorkPumping Requires Work
You do work as you pump water into the You do work as you pump water into the pipepipe You squeeze the water inward – the force You squeeze the water inward – the force The water moves inward – the distanceThe water moves inward – the distance In this case, the work you do is:In this case, the work you do is:
work = pressure· volumework = pressure· volume The pressurized water carries your work The pressurized water carries your work
with itwith it We’ll call this work “pressure potential We’ll call this work “pressure potential
energy”energy”
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Question 3Question 3
Where does the work you do Where does the work you do pumping water go?pumping water go?
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Pressure Potential Pressure Potential EnergyEnergy
Pressure potential energy is unusual Pressure potential energy is unusual becausebecause it’s not really stored in the pressurized water, it’s not really stored in the pressurized water, it’s promised by the water’s pressure source.it’s promised by the water’s pressure source.
In steady state flow (SSF),In steady state flow (SSF), which is steady flow in motionless surroundings,which is steady flow in motionless surroundings, promised energy is as good as stored energypromised energy is as good as stored energy pressure potential energy (PPE) is meaningfulpressure potential energy (PPE) is meaningful
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Question 4Question 4
As water flows, what happens to its As water flows, what happens to its energy?energy?
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Energy and Bernoulli Energy and Bernoulli (no (no gravity)gravity)
In SSF, water flows along streamlinesIn SSF, water flows along streamlines Water flowing along a single Water flowing along a single
streamline in SSFstreamline in SSF has both PPE and kinetic energy (KE),has both PPE and kinetic energy (KE), must have a constant total energy per must have a constant total energy per
volume,volume, and obeys Bernoulli’s equation (no and obeys Bernoulli’s equation (no
gravity):gravity):
PPE/Vol + KE/Vol = Constant/VolPPE/Vol + KE/Vol = Constant/Vol
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How Water Moves How Water Moves (with (with gravity)gravity)
Weight contributes to the net force on Weight contributes to the net force on waterwater
Without a pressure imbalance, water fallsWithout a pressure imbalance, water falls Water in equilibrium has a pressure Water in equilibrium has a pressure
gradientgradient Water’s pressure decreases with altitudeWater’s pressure decreases with altitude Water’s pressure increases with depthWater’s pressure increases with depth
Water has gravitational potential energy Water has gravitational potential energy (GPE)(GPE)
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Energy and Bernoulli Energy and Bernoulli (with (with gravity)gravity)
Water flowing along a single Water flowing along a single streamline in SSFstreamline in SSF has PPE, KE, and GPE,has PPE, KE, and GPE, must have a constant total energy per must have a constant total energy per
volume,volume, and obeys Bernoulli’s equation (with and obeys Bernoulli’s equation (with
gravity):gravity):
PPE/Vol + KE/Vol + GPE/Vol = PPE/Vol + KE/Vol + GPE/Vol = Constant/VolConstant/Vol
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Energy Transformations Energy Transformations (part 1)(part 1)
As water flows upward in a uniform pipe,As water flows upward in a uniform pipe, its speed can’t change, soits speed can’t change, so its gravitational potential energy increasesits gravitational potential energy increases and its pressure potential energy decreases.and its pressure potential energy decreases.
As water flows downward in a uniform As water flows downward in a uniform pipe,pipe, its speed can’t change, soits speed can’t change, so its gravitational potential energy decreasesits gravitational potential energy decreases and its pressure potential energy increases.and its pressure potential energy increases.
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Energy Transformations Energy Transformations (part 2)(part 2)
As water rises upward from a fountain As water rises upward from a fountain nozzle,nozzle, its pressure stays constant (atmospheric), soits pressure stays constant (atmospheric), so its gravitational potential energy increasesits gravitational potential energy increases and its kinetic energy decreases.and its kinetic energy decreases.
As water falls downward from a spout,As water falls downward from a spout, its pressure stays constant (atmospheric), soits pressure stays constant (atmospheric), so its gravitational potential energy decreasesits gravitational potential energy decreases and its kinetic energy increases.and its kinetic energy increases.
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Energy Transformations Energy Transformations (part 3)(part 3)
As water sprays horizontally from a nozzle,As water sprays horizontally from a nozzle, its height is constant, soits height is constant, so its kinetic energy increasesits kinetic energy increases and its pressure potential energy decreases.and its pressure potential energy decreases.
As a horizontal stream of water hits a wall,As a horizontal stream of water hits a wall, its height is constant, soits height is constant, so its kinetic energy decreasesits kinetic energy decreases and its pressure potential energy increases.and its pressure potential energy increases.
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Introductory Question Introductory Question (revisited)(revisited)
Water enters your home plumbing Water enters your home plumbing at ground level. Where will you get at ground level. Where will you get the strongest spray from a shower?the strongest spray from a shower?
A.A. In the ground floor showerIn the ground floor shower
B.B. In the basement showerIn the basement shower
C.C. In the second floor showerIn the second floor shower
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Summary aboutSummary aboutWater DistributionWater Distribution
Water’s energy remains constant during Water’s energy remains constant during SSFSSF
Water’s energy changes form as itWater’s energy changes form as it flows upward or downward inside pipes,flows upward or downward inside pipes, rises or falls in open sprays,rises or falls in open sprays, and shoots out of nozzles or collides with and shoots out of nozzles or collides with
objects.objects. Water distribution can driven byWater distribution can driven by
pressurized water (PPE)pressurized water (PPE) elevated water (GPE)elevated water (GPE) fast-moving water (KE)fast-moving water (KE)
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