Chapter 13 States of Matter

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Chapter 13States of Matter
Fluid - A material flows and have no definite
shape of their own.
Pascals Principle The change in pressure
applied at any point in a confined fluid is
transmitted undiminished throughout the fluid.

• Examples
• Toothpaste
• Hydraulics

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How much can be lifted?
F1/A1 F2/A2
F2 F1A2/A1
F2 (20 N)(.1 m2)/(.05 m2) 40 N
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If the little piston moves 1 meter, how far does
the big one move?
V1V2
A1H1A2H2
H2 (.05 m2)(1m)/(.1 m2)
H2 A1H1/A2
H2 .5 m
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Chapter 13States of Matter
Swimming under pressure
But d m/v or m dv
P hdg
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Chapter 13States of Matter
Taking P hdg and multiplying both sides by A
gives
PA Ahdg or F vdg
Where F vdg is the buoyant force
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Chapter 13States of Matter

• Archimedes Principle - An object immersed in a
  fluid has an upward force on it equal to the
  weight of the fluid displaced by the object.
• A body sinks if the weight of the fluid it
  displaces is less than the weight of the body.
• A submerged body remains in equilibrium if the
  weight of the fluid it displaces exactly equals
  its own weight.
• A body floats if it displaces a weight greater
  than that of its own weight

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Chapter 13 States of Matter

• A block of wood has a volume of 100 cm3 and a
  mass of 85 grams.
• Will it float in water ?water 1000 kg/m3 ?
• Will it float in gas ?gas 700 kg/m3

YES
NO
d m/v 85g/100 cm3 .85 g/cm3 850 kg/m3
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Chapter 13States of Matter
What is the weight of a rock submerged in water
if the rock weighs 30 newtons and has a volume of
.002 m3?
V .002 m3 W 30 N ?water 1000 kg/m3
Fnet Weight - buoyant force
Fnet mg - vdg
Fnet 30 N - (.002 m3)(1000 kg/m3)(9.8 m/s2)
Fnet 30 N - 19.6 N 10.4 N
The acceleration of the rock will be a F/m
A 10.4 N/3.06 kg 3.2 m/s2
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Chapter 13States of Matter
What the maximum weight a helium balloon of
volume 2 m3 can support in air?
V 2 m3 ?air 1.2 kg/m3 ?helium
.177 kg/m3
Fnet Weight - buoyant force
Fnet mg - vdg
Fnet (2m3)(.177kg/m3)(9.8m/s2)-(2m3)(1.2
kg/m3)(9.8 m/s2)
It can support 20 N
Fnet 3.462 N - 23.52 N
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Chapter 13States of Matter
Bernouillis Principle For the horizontal flow
of a fluid through a tube, the sum of the kinetic
energy per unit volume and the pressure is a
constant.
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Chapter 13States of Matter

• Cohesion The force of attraction between like
  particles.
• Adhesion The force of attraction between unlike
  particles.
• Capillary action The rise of a liquid in a
  narrow tube because the adhesive force is
  stronger than the cohesive force.
• Volatile Liquid A liquid that evaporates quickly.

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Chapter 13States of Matter

• Adhesion

• Cohesion

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Chapter 13 States of Matter

• Surface Tension
• The tendency of the
• surface of a liquid to
• contract to the smallest
• possible area

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Chapter 13States of Matter
Sublimation
Melting
Vaporization
Solid Liquid
Gas
Condensation
Freezing
Supercooled
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Chapter 13States of Matter
Thermal Expansion The increase in length or
volume of a substance when heated.
Linear expansion L2 L1aL1(T2-T1)
Chart Pg 317
Volume expansion V2 V1ßV1(T2-T1)
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Chapter 13States of Matter
A iron bar is 3 m long at 21ºC. What is the
length of the bar at 100º C?
Linear expansion L2 L1aL1(T2-T1)
L2 3 m(12 x 10 6 (ºC-1)(3 m)(100ºC- 21ºC)
L2 3 m .002844 m 3.002844 m