Solids and Fluids
States of Matter
Deformation of Solids
Density and Pressure
Familiar States of Matter
• Solids – atoms held together by ___________ forces
– Crystalline has _________ structure (a)
– Amorphous has __________ structure (b)
• Liquids – forces do not keep atoms/molecules in fixed
positions and they can _______ (c)
• Gases – molecules in constant _________ motion, widely
separated, and only exert ______ forces on each other
Fig. 9.2, p. 269
Exotic States of Matter
• Plasma – like a gas but
electrons are ________
from atoms
• Dark Matter – _______,
inferred from motion of
stars orbiting centers of
galaxies
• Dark Energy – invisible,
one explanation for
rapid ___________ of
universe
Deformation of Solids:
Stress and Strain
• Stress is the ______ ___
____ _____ causing
deformation
• Strain is a measure of
the _________ of
deformation
• For small stresses,
stress is __________ to
strain
stress  elastic modulus  strain
Fig. 9.4, p. 271
9.1
Young’s Modulus: Elasticity in Length
Fig. 9.3, p. 270
F
L
Y
A
L0
9.3
• Force is __________ to
area A
• Force is “tensile” –
produces ________
• Tensile ______ is L/L0
• Force per unit area has
units of ________ (Pa)
• Y is Young’s modulus
1 Pa  1 N m
2
Shear Modulus: Elasticity of Shape
Fig. 9.4, p. 271
•
•
•
•
Force is ________ to area A
Force produces ____ stress
Shear ______ is x/h
S is Shear modulus
F
x
S
A
h
9.3
Bulk Modulus: Volume Elasticity
Fig. 9.6, p. 272
• Force _______ applied to
all sides (perpendicular)
• Volume ____ is P=F/A
• Volume _____ is V/V
• B is Bulk modulus
• B is always ________
• _____________ is B-1
V
P   B
V
9.5
Density and Pressure
• Density is mass _______ by volume
• Specific gravity is ratio of density to density of
_______
• Pressure is ______ per unit area
• In a fluid molecules are free to move so it can
not sustain a _____ stress, only _____ stresses
M

V
9.6
F
P
A
9.7
Pressure Variation with Depth
• Fluid at rest in container
• All portions in static __________
• All points at same depth at same
___________
• Consider shaded volume
P2 A  P1 A  Mg  0
Fig. 9.11b, p. 279
M  V   Ah   A y1  y2 
9.10
9.11
P2  P1   g  y1  y2 
P  P0   gh
Pascal’s Principle
• A change in __________
applied to an enclosed fluid
is transmitted ___________
to every point in the fluid
and the walls of the
container.
Fig. 9.14a, p. 281
P1  P2
F1 A1  F2 A2
F2  F1 A2 A1
Measuring Pressure
• Open tube manometer
• Gauge pressure is P − P0
P  PA  PB  P0   gh
• Barometer
• Gives atmospheric pressure P0
• 1 atm equivalent to 0.76 m of Hg
Fig. 9.16, p. 283
Archimedes’ Principle
• Buoyant force is equal to the weight of fluid ________
by an object
B  fluidVfluid g
9.12b
• Objects less dense
than fluid ____ (a)
• Objects more dense
than fluid ____ (b)
Fig. 9.19, p. 286
Totally Submerged Objects
Vfl  Vobj
Examine Newton’s 2nd Law

 F  B  mg  ma

 F  flVobjg  objVobjg  fl  obj Vobjg

fl
  obj Vobj g  ma
Floating Objects
Vfl  Vobj
Examine Newton’s 2nd Law

 F  B  mg  0
Fig. 9.20, p. 286
B  mg
 flVfl g   objVobj g
 obj Vfl

 fl Vobj
9.13