Introduction
Introduction
to
to
Materials
Materials
Properties of Matter
Properties of Matter
Phases (5)
Phases (5)
Solid, liquid, gas,
Solid, liquid, gas,
plasma,
plasma,
Bose-Einstein Condensate
Bose-Einstein Condensate
Solid: definite volume,
Solid: definite volume,
definite shape
definite shape
Liquid: definite volume, no
Liquid: definite volume, no
definite shape
definite shape
Gas: no definite volume,
Gas: no definite volume,
Properties of Matter
Properties of Matter
Phases (5) (cont.)
Phases (5) (cont.)
Plasma:
Plasma:
not a common state on Earth,
not a common state on Earth,
but may be the most common state of
but may be the most common state of
matter in the universe. Plasma consists
matter in the universe. Plasma consists
of highly charged particles with
of highly charged particles with
extremely high kinetic energy. Stars are
extremely high kinetic energy. Stars are
essentially superheated balls of plasma.
essentially superheated balls of plasma.
Bose-Einstein Condensate:
Bose-Einstein Condensate:
At extremely
At extremely
low temperatures, molecular motion
low temperatures, molecular motion
comes very close to stopping altogether.
comes very close to stopping altogether.
Since there is almost no kinetic energy
Since there is almost no kinetic energy
being transferred from one atom to
being transferred from one atom to
another, the atoms begin to clump
another, the atoms begin to clump
together. There are no longer thousands
together. There are no longer thousands
of separate atoms, just one “super
of separate atoms, just one “super
atom.”
Properties of Matter
Properties of Matter
Solids:
Solids:
Density: D = M/V (unit g/cm
Density: D = M/V (unit g/cm
33)
)
Elasticity
Elasticity
Hooke’s Law:
Hooke’s Law:
The strain is
The strain is
directly proportional to the
directly proportional to the
stress, as long as the elastic limit
stress, as long as the elastic limit
is not exceeded.
is not exceeded.
Hooke’s Law
Stresses (types of forces):
Stresses (types of forces):
Compression (pushes in) and
Compression (pushes in) and
Tension (pulls apart)
Liquids
Liquids
Pressure
Pressure
The pressure a liquid
The pressure a liquid
exerts depends ONLY on
exerts depends ONLY on
its density and depth (NOT
its density and depth (NOT
weight or volume!).
weight or volume!).
Equation: Pressure equals
Equation: Pressure equals
Force/Area (P=F/A)
Force/Area (P=F/A)
Unit is a Pascal (Pa)
Unit is a Pascal (Pa)
Liquids
Liquids
Buoyancy
Buoyancy
Definition Buoyant force: Force
Definition Buoyant force: Force
a fluid exerts on an object
a fluid exerts on an object
immersed in it.
immersed in it.
Archimedes’ Principle
Archimedes’ Principle
: An
: An
immersed object (completely OR
immersed object (completely OR
partially submerged) is buoyed
partially submerged) is buoyed
up by a force equal to the weight
up by a force equal to the weight
of the fluid it displaces.
of the fluid it displaces.
Great summary!
Liquids (cont.)
Liquids (cont.)
Pascal’s Principle:
Pascal’s Principle:
Changes in
Changes in
pressure in an enclosed fluid at rest
pressure in an enclosed fluid at rest
are transmitted unchanged to all
are transmitted unchanged to all
points in the fluid and in all
points in the fluid and in all
directions.
directions.
Hydraulic press: P
Hydraulic press: P
left
left
= P
= P
rightrightor f/a = F/A
or f/a = F/A
Video
of a
of a
example problem
example problem
worked out.
worked out.
But what you gain
But what you gain
in force, you lose
in force, you lose
in distance!!!
Gases
Gases
Gas (air) pressureGas (air) pressure
Pressure in gas is different than in solids or Pressure in gas is different than in solids or
liquids. Pressure is due to the
liquids. Pressure is due to the collisionscollisions of of the gas particles on the object in the gas. It
the gas particles on the object in the gas. It
is NOT a downward force due to gravity, but
is NOT a downward force due to gravity, but
it depends on the number of gas particles
it depends on the number of gas particles
and the gases’ temperature.
and the gases’ temperature.
To increase gas pressure eitherTo increase gas pressure either
Increase the amount of gasIncrease the amount of gas
Increase the temperature of the gas Increase the temperature of the gas
(faster moving particles
(faster moving particles
Because of air pressure (14.7 lbs/in2 or Because of air pressure (14.7 lbs/in2 or
101.3 kPa), straws and pumps CANNOT
101.3 kPa), straws and pumps CANNOT
pump liquids higher than
pump liquids higher than 10.3 m10.3 m maximum maximum height!!
Gases
Gases
Buoyancy of air: same idea as liquidsBuoyancy of air: same idea as liquids
Helium balloons rise because the buoyancy Helium balloons rise because the buoyancy force on them is greater than the weight of
force on them is greater than the weight of
the air they displace.
the air they displace.
Bernoulli’s Principle (read the lab report) Bernoulli’s Principle (read the lab report)
Daniel Bernoulli Good videoGood video
““When the speed of a fluid increases, the When the speed of a fluid increases, the internal pressure drops.
internal pressure drops.
Applies to both liquids and gasesApplies to both liquids and gases
Applies only to steady (laminar) flow, not Applies only to steady (laminar) flow, not
turbulent (eddies form)
turbulent (eddies form)
Stream flow (reason for rapids) and Stream flow (reason for rapids) and
Airplanes
Forces on an airplane:
4 Laws of Thermodynamics
4 Laws of Thermodynamics
Zeroth Law: Two objects that are
Zeroth Law:
each in thermal equilibrium with
a third object are also in thermal
equilibrium with one another.
If A is in thermal equilibrium with B
and B is in thermal equilibrium with
C, then A is in thermal equilibrium
with C.
First Law: The change in a
stationary object’s internal energy
is equal to the heat transferred into
that object minus the work that
object does on its surroundings
∆E = Q - W
Whenever heat is added to a system,
it transforms to an equal amount of
some other form of energy – either
work is done and/or internal energy
is increased!!
Second Law: The entropy of a
thermally isolated system of
objects NEVER decreases.
Definition ENTROPY: The measure of the
disorder in a system.
Chaos, disorder, ALWAYS increases in a system
left on its own.
PE is always less than E
o
In the process of energy transfer, some energy
will dissipate as heat.
Heat will NEVER of itself flow from a cold object
to a hot object.
As a result of this fact, natural processes that
involve energy transfer must have one direction, and all natural processes are irreversible.
Therefore, both matter and energy in the
Third Law: As an object’s
temperature approaches absolute
zero, its entropy approaches zero.
ALL processes cease as temperature
approaches zero.
If all the thermal motion of molecules
(KE) could be removed, a state called
absolute zero would occur.
HEAT DEATH of the UNIVERSE: The
Universe will attain absolute zero
when all energy and matter is
LAWS OF THERMODYNMICS (ver. 2)
0) You have to play the game!
1) You can’t win!
You cannot get something for nothing,
because matter and energy are
conserved.
2) You can’t break even, unless it gets
incredibly cold!
You cannot return to the same energy
state, because there is always an
increase in entropy.
3) It never gets that cold!
Because absolute zero is
Thermodynamic Definitions:
Thermodynamic Definitions:
Thermodynamics: study of heat and related
Thermodynamics: study of heat and related
phenomena.
phenomena.
Heat: flow of energy from a high temperature
Heat: flow of energy from a high temperature
location to a low temperature location. Objects don’t
location to a low temperature location. Objects don’t
contain “heat.”
contain “heat.”
Internal energy: grand total of all energies in an
Internal energy: grand total of all energies in an
object
object
Temperature: is simply what a thermometer reads. It
Temperature: is simply what a thermometer reads. It
is a comparison of an object’s internal energy to a
is a comparison of an object’s internal energy to a
standard.
standard.
Thermal equilibrium: occurs when no heat flows
Thermal equilibrium: occurs when no heat flows
between 2 objects. They are at the same
between 2 objects. They are at the same
temperature.
Thermodynamic Definitions:
Thermodynamic Definitions:
Calorie (cal): Unit for heat energy, 1 cal = 4.184 J Calorie (cal): Unit for heat energy, 1 cal = 4.184 J
Kelvin Scale: SI scale, no negative temps and no degreesKelvin Scale: SI scale, no negative temps and no degrees
Absolute Zero: is reached when an object has zero Absolute Zero: is reached when an object has zero
internal energy.
internal energy.
3 ways to transfer heat energy: Radiation, Conduction, 3 ways to transfer heat energy: Radiation, Conduction,
Convection
Convection
Heat Pump: device that transfers heat from a colder area Heat Pump: device that transfers heat from a colder area
to a hotter area by using electrical or mechanical energy
to a hotter area by using electrical or mechanical energy
(e.g. refrigerators, freezers, AC).
(e.g. refrigerators, freezers, AC).
Heat Engine: device that converts heat to mechanical Heat Engine: device that converts heat to mechanical
energy, which can then be used to do mechanical work
energy, which can then be used to do mechanical work
(e.g. steam engines, gasoline engines)
Thermodynamic Vids
Thermodynamic Vids
4 laws of Thermo
4 laws of Thermo
Heat and Temperature
Heat and Temperature
Conduction, convection, radiation
Conduction, convection, radiation
1st Law of Thermo
1st Law of Thermo
2nd Law of Thermo
2nd Law of Thermo
