Chapter 13 Lesson 1

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Chapter 13Lesson 1

• Pressure

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I. Pressure

• A. Def the amount of force exerted over an
  area.
• 1. Tires gases push on the outside walls of
  tires
• B. Formula - P F / A
• C. Measured in Pascals (N/m2)
• 1. 101.3 kPa at Sea level
• 2. 1000 Pa 1 kPa

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• D. Our Atmosphere
• 1. Gas layer that covers the earth.
• 2. Perfect amount of gases
• a. Nitrogen 78
• b. Oxygen 21
• c. Carbon Dioxide - .04
• d. Water vapor, dust, argon
• 3. Air pressure ?s as altitude increases
• (Indirect)

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• E. A book has a force of 30 Newton's while
  resting on a table. If the area of the book is
  0.06 m2, how much pressure does the book exert?
• P F / A
• 30 N / 0.06 m2
• 500 Pa
• Or 0.5 kPa

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Chapter 13Lesson 2

• Forces and Pressures in Fluids

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I. Pascals Principle

• A. Def a pressure applied to a fluid is
  transmitted throughout the whole fluid.
• 1. Squeezing toothpaste
• 2. Squeezing one end of a
• balloon
• B. Hydraulic Machine uses oil like liquid to
  multiply input force up to 10x.

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II. Bernoullis Principle

• A. Def as the velocity of a fluid increases,
  the pressure of the fluid decreases.
• 1. Ex blowing 2 pop cans.

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• 2. Airplanes (pg. 213)

Low Pressure
High Pressure
High to Low causes lift for an airplane
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• As the airplane speeds down the runway, air
  rushes over and under the wings. The air, going
  over the wings, goes faster and faster, there is
  less and less pressure above the wings. Soon
  there is much more pressure below the wings than
  above. This pressure pushes up on the wings and
  the airplane is lifted into the sky.

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DEMO

• -Fill a beaker or cup full of water to the brim.
• -Add one drop of food coloring
• -Insert a straw to the middle of the beaker
  vertically.
• -Blow across the top of the straw. Notice the
  water inside of the straw.
• -What happens and why?

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• 3. Venturi Effect
• a. Def reduced air pressure outside of
  skyscrapers has caused windows to be blown out.

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High Pressure
High Pressure
Low Pressure
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• 13.2 Assignment Write a paragraph for why a
  curve ball in baseball demonstrates the
  Bernoulli Principle.

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Chapter 13Lesson 3

• Buoyancy

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• What Archimedes realized about buoyancy
  Archimedes solved many problems for King Heiro of
  Syracuse. His most famous solution is associated
  with Heiro's new crown. Heiro had given the
  goldsmith the exact amount of gold needed for the
  crown. After it was made, Heiro suspected that it
  might not have as much gold as it was supposed
  to. King Heiro summoned Archimedes, and
  Archimedes was bewildered with the king's
  problem. But later, when Archimedes got into his
  full bathtub, it occurred to him that the volume
  of water that spilled out of the tub was equal to
  the volume he displaced. Reasoning that a much
  lower volume of water would be displaced by
  something denser (like gold) even though of equal
  weight, he saw the answer to the king's problem.
  The next day Archimedes told they king of his
  discovery. Archimedes put the king's new crown in
  a tub of water and found that the crown indeed
  displaced more water than the same weight of gold
  (it occupied more volume because it had been
  adulterated with lower density silver). The
  goldsmith was immediately beheaded.

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• I. Buoyancy
• A. Def the ability of a fluid to exert an
  upward force on an object placed in it.
• 1. results in an apparent loss of
  _________
• ? easy to lift
• ? opposite of gravity
• B. History
• 1. Archimedes's Principle
• ?the buoyant force on an object is equal to
  the weight of fluid displaced by the object.

Weight
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• In other wordsthink of the clay activity we did
  earlier in this chapter.

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• C. Two Ways to tell if an object can float
• 1. Density
• gt 1
• lt 1
• 2. Force Analysis
• ? weight vs. buoyant force
• weight gt buoyant force
• weight lt buoyant force

sink
float
sink
float
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• weight buoyant force
• suspended

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Quiz Review Content

• Know Pascals Principle and what it applies to.
• Know the pressure equation and units
• What is the definition of a fluid?
• What is the relationship between altitude and
  pressure?
• Know Bernoullis Principle and what it applies
  to.
• Know what the Venturi Effect is.
• Be able to calculate force, area, and pressure.
  SHOW YOUR WORK!!!!!
• There is also an extra credit question on the
  quiz, but you will have to get it right to get
  the extra credit.