© 2010 Pearson Education, Inc. PowerPoint ® Lectures for College Physics: A Strategic Approach,...
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© 2010 Pearson Education, Inc. PowerPoint ® Lectures for College Physics: A Strategic Approach, Second Edition Chapter 13 Fluids
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Transcript of © 2010 Pearson Education, Inc. PowerPoint ® Lectures for College Physics: A Strategic Approach,...
© 2010 Pearson Education, Inc.
PowerPoint® Lectures forCollege Physics: A Strategic Approach, Second Edition
Chapter 13
Fluids
© 2010 Pearson Education, Inc. Slide 13-2
13 Fluids
© 2010 Pearson Education, Inc. Slide 13-3
© 2010 Pearson Education, Inc. Slide 13-4
© 2010 Pearson Education, Inc. Slide 13-5
© 2010 Pearson Education, Inc.
Reading Quiz1. The SI unit of pressure is
A. N
B. kg/m2
C. Pa
D. kg/m3
Slide 13-6
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Answer1. The SI unit of pressure is
A. N
B. kg/m2
C. Pa
D. kg/m3
Slide 13-7
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Reading Quiz2. Gauge pressure is true pressure. Explain.
A. larger than
B. smaller than
C. the same as
D. None of the above
Slide 13-8
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Answer2. Gauge pressure is true pressure. Explain.
A. larger than
B. smaller than
C. the same as
D. None of the above
Slide 13-9
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Reading Quiz3. The buoyant force on an object submerged in a liquid depends
on
A. the object’s mass.
B. the object’s volume.
C. the density of the liquid.
D. both B and C.
Slide 13-10
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Answer 3. The buoyant force on an object submerged in a liquid depends
on
A. the object’s mass.
B. the object’s volume.
C. the density of the liquid.
D. both B and C.
Slide 13-11
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Density
Slide 13-12
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Pressure
The pressure of the water behind each hole pushes the water out.
The SI unit of pressure is 1 pascal = 1 Pa = 1 N/m2.
Slide 13-13
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Pressure in a Liquid Increases with Depth
Slide 13-14
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Example ProblemIn a graduated cylinder, 10 cm of oil (ρ = 0.85 g/cm3) floats on top of 20 cm of water (ρ = 1.00 g/cm3). What is the pressure at a height of 10 cm from the bottom of the cylinder?
Slide 13-15
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Atmospheric Pressure
patmos = 1 atm = 103,000 PaSlide 13-16
© 2010 Pearson Education, Inc. Slide 13-17
© 2010 Pearson Education, Inc.
Example ProblemThe gas in the cylinder is at a pressure of pgas = 3.0 x 105 Pa. How high is the column of mercury?
3
Slide 13-18
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The Barometer
Slide 13-19
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Pressure Units
Slide 13-20
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Buoyancy
Slide 13-21
© 2010 Pearson Education, Inc. Slide 13-22
© 2010 Pearson Education, Inc.
FloatingWhen the object sinks to the point that the weight of the displaced fluid equals the weight of the object, then the forces balance and the object floats in equilibrium. No net force.
The volume of fluid displaced by a floating object of density o and volume Vo is
The density of ice is 90% that of water.
When ice floats, the displaced water is 90% of the volume of ice. Thus 90% of the ice is below water and 10% is above.
Slide 13-23
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How a Boat Floats
Slide 13-24
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Checking UnderstandingTwo blocks of identical size are submerged in water. One is made of lead (heavy), the other of aluminum (light). Upon which is the buoyant force greater?
A. On the lead block.
B. On the aluminum block.
C. They both experience the same buoyant force.
Slide 13-25
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Answer Two blocks of identical size are submerged in water. One is made of lead (heavy), the other of aluminum (light). Upon which is the buoyant force greater?
A. On the lead block.
B. On the aluminum block.
C. They both experience the same buoyant force.
Slide 13-26
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Checking UnderstandingTwo blocks are of identical size. One is made of lead, and sits on the bottom of a pond; the other is of wood and floats on top. Upon which is the buoyant force greater?
A. On the lead block.
B. On the wood block.
C. They both experience the same buoyant force.
Slide 13-27
© 2010 Pearson Education, Inc.
Answer Two blocks are of identical size. One is made of lead, and sits on the bottom of a pond; the other is of wood and floats on top. Upon which is the buoyant force greater?
A. On the lead block.
B. On the wood block.
C. They both experience the same buoyant force.
Slide 13-28
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Checking UnderstandingA barge filled with ore floats in a canal lock. If the ore is tossed overboard into the lock, the water level in the lock will
A. rise.
B. fall.
C. remain the same.
Slide 13-29
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Answer A barge filled with ore floats in a canal lock. If the ore is tossed overboard into the lock, the water level in the lock will
A. rise.
B. fall.
C. remain the same.
Slide 13-30
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Example ProblemA block of plastic floats in water. 20% of the block’s volume is above the waterline. What is the density of the block?
Slide 13-31
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A ball weighing 1.0 N has a density 1/3 that of water. What is the tension in the string when the ball is held under water as shown?
Example Problem
Slide 13-32
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Constrained Flow: Continuity
Slide 13-33
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Acceleration of Fluids
Slide 13-34
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Pressure Gradient in a Fluid
Slide 13-35
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Bernoulli’s Equation
Slide 13-36
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Example ProblemIn an agricultural irrigation system, water is pumped through a constant-diameter pipe up a 1.5-m-high embankment, where it empties into a field. If the farmer wants to pump water at a rate of 20 L/s, what pressure does his pump need to apply at the bottom of the pipe?
Slide 13-37
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Viscosity
Slide 13-38
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Poiseuille’s Equation
Slide 13-39
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Example ProblemA garden hose is 10 m long and has an inner diameter of 2.5 cm. Using this hose it takes 5.0 s to fill a 10 L bucket. What is the water pressure at the spigot end of the hose?
Slide 13-40
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Summary
Slide 13-41
© 2010 Pearson Education, Inc.
Summary
Slide 13-42
