Test 2 Review
Chapters 11 -20
Chapter 11 – Atomic Nature of Matter
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Summary of Terms
– Atom
– Brownian Motion
– Atomic Nucleus
– Electron
– Proton
– Neutron
– Atomic Number
– Atomic Mass Unit (AMU)
– Isotopes
– Periodic table
– Compound
– Molecule
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Chemical reaction
Mixture
Quantum Mechanics
Antimatter
Dark Matter
Atoms Are Composite Objects
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Protons (+ electric charge), p
Electrons (– electric charge), e
Neutrons (no charge), n
Proton and Neutron have about the same mass
Electron is about 2000 times less massive than proton
Electrical Forces produce attraction between electrons and the
protons in the nucleus (they are oppositely charged)
Chemical elements are defined by the
number of protons in the atom’s nucleus
• Hydrogen: 1 proton & 1 electron
Cloud of
“electron probability”
proton
10-10 m
Carbon has 6 protons
Cloud of 6 electrons
Nucleus:
6 protons
6 or 7 neutrons
The Periodic Table
alkali
earths
Elements in columns (groups) have similar
outer-electron configurations,
and so tend to behave similarly.
transition metals
halogens
rare
earths
noble gases
actinides
Structure of the Atom
Chapter 12 - Solids
• Summary of Terms
– Atomic binding
– Density
– Elasticity
– Hooke’s law
– Scaling
Density
• Mass Density = Mass/Volume
• Weight Density = Weight/Volume
• Units are Kg/m3
• Water density is 1000 Kg/m3 or 1 g/cm3
Chapter 13 - Liquids
• Summary of Terms
– Pressure
– Buoyant force
– Archimedes principle
– Principle of floatation
– Pascal’s principle
– Surface tension
– Capillarity
Pressure
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Pressure = force / area
Standard International (SI) units are Pascals
1N/m2 = 1 Pa about pressure of dollar bill on a table.
Liquid pressure = weight density x depth
– Independent of volume!!!
• For fresh water density is 1000 kg/m3
• For water, weight density is 1000*9.8 = 9800N/m3
• (liquid density is almost constant – Liquids are almost
incompressible!)
Archimedes’ Principle
• An immersed body is buoyed up by a force equal to the weight of
the fluid it displaces.
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True for Liquids and Gases
Objects weigh more in air than in liquid!
If an object is denser than fluid, it will sink.
If an object is less dense it will float.
If an object has equal density it will neither float or sink – like a
fish.
– If a 25 kg object displaces 20 kg fluid, it’s apparent weight is 5 kg
Pascal’s Principle
• A change in pressure at any point in an enclosed fluid at rest is
transmitted undiminished to all points in the fluid.
Surface Tension & Capillary Action
• Liquid surfaces tend to contract and force each drop into shape
having least surface area.
• On the space shuttle, water drops are spherical!
• Attraction of unlike surfaces is called Adhesion, like water in thin
glass tubes. Molecules act as sticky balls on the glass.
• Attraction of like surfaces is cohesion.
Chapter 14 – Gases and Plasmas
• Summary of Terms
– Atmospheric pressure
– Barometer
– Boyle’s law
– Archimedes principle for air
– Bernoulli’s principle
– Plasma
Atmosphere
• Dry air at 20o C has a density of 1.21 kg/m3 which is about 2 ¾ lbs.
• Barometers measure air pressure
– Need 10.3 meters of water in a pipe to balance atmosphere
(depends on atmospheric pressure).
– Turn long pipe of water into a bucket of water and water level in
pipe will be 10.3 M with vacuum above water in pipe.
Boyle’s Law
P1V1 = P2V2
• Holds for constant temperature
• Pressure is proportional to density – when volume is decreased,
density and pressure increase
• Double pressure by decreasing volume by half
Archimedes’ Principle – Again!
• An immersed body is buoyed up by a force equal to the weight of
the fluid it displaces.
– Is valid for gasses as well as liquids!
– Objects weigh more in a vacuum than in air!
Bernoulli’s Principle
Water speeds up in narrower pipes!
Where Speed of fluid increases, pressure in fluid decreases
Holds for Laminar air flow (smooth flow, not turbulent).
Plasma – the Fourth State of Matter
• Solid
Liquid
Gas
Plasma
Increasing Temperature 
Plasmas are generally greater than 10,000 degrees
Plasma – the Fourth State of Matter
• A plasma is an ionized gas that responds to electric and magnetic
fields.
• The visible universe is made of 99% plasma.
• The sun is a giant ball of plasma
• High temperature Plasma must be contained in magnetic bottles. If
the plasma were to come into contact with a physical container, it
would vaporize the container.
• Lightning is a plasma
• Fusion power research uses a plasma at ~ 10M oC
Chapter 15 – Temperature, Heat and
Expansion
• Summary of Terms
– Temperature
– Absolute zero
– Heat
– Internal energy
– Specific heat capacity
Temperature Scales
The Celsius Scale
• How does one create a scale?
– It comes from experiment
Divide this
distance into
100 even
parts =
1 oC intervals
on the Celsius
“scale”
level of mercury when placed in
boiling water -call this 100 OC
observed level of mercury when
placed in freezing pure water, call
this 0oC
Mercury, let’s say
Kelvin Scale
• The theoretical temperature of -273.15 oC turns out to be the
same for many different gasses.
• -273.15 oC is not observed experimentally.
• We use this extrapolated zero-pressure temperature as a basis
of a new temperature scale with it’s zero at this theoretical
temperature. Named after Lord Kelvin 1824-1907
Concept of Heat
• Heat refers to a transfer of energy from one body to another
• Heat DOES NOT refer to the amount of energy “contained” in a
body or system.
Heat always flows from the hotter object to the cooler object
independent of the amount of “heat energy” each object
contains
Specific Heat
• Different substances have different capacities for storing internal
energy
• The specific heat capacity of any substance is defined as the
quantity of heat required to change the temperature of a unit
mass of the substance by 1 degree
• Consider it as “thermal inertia”
• The more heat energy it takes to raise a substances temperature,
the more heat energy is given up by the substance as it cools
down!!!
Thermal expansion of Materials
• Suppose you have a rod with some initial length Lo at some
initial temperature To. When the temperature changes by T,
the length will change by an amount L.
• Experiment shows that L is directly proportional to T provided
T is less than about 100 oC.
Lo
L
Water
Chapter 16 – Heat Transfer
• Summary of Terms
– Conduction
– Convection
– Radiation
– Newton’s law of cooling
– Greenhouse effect
– Solar Constant
– Solar Power
Chapter 17 – Change of Phase
• Summary of Terms
– Evaporation
– Sublimation
– Condensation
– Boiling
– Melting
– Regelation
Change of Phase
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Evaporation
Condensation
Fogs and Clouds
Boiling
Melting and Freezing
Energy and Change of Phase
Change of Phase
• Evaporation
– Fast molecules escape the liquid, taking energy, and leaving the
liquid cooler.
– Evaporation is a cooling process!
• Condensation
– Slow molecules condense leaving the air warmer.
– Condensation is a warming process
• Boiling
– Boiling is a cooling process
– Temperature is 100 degrees C no matter how much heat we give
the water.
– Water boils as fast as it is being warmed by heating.
– The steam carries away the heat
Energy in Condensation/Vaporization
• The Heat of Vaporization is 540 calories per gram of condensed
water at 100 degrees.
Energy and Phase Changes
Energy
Chapter 18 – Thermodynamics
• Summary of Terms
– Thermodynamics
– Absolute zero
– Internal Energy
– First law of thermodynamics
– Adiabatic process
– Temperature inversion
– Second law of thermodynamics
– Heat engine
– Entropy
1st Law of Thermodynamics
• Conservation of energy
• When heat flows to or from a system, the system gains or loses an
amount of energy equal to the amount of heat transferred
• Heat added to system = increase in internal energy + external work
done by the system
• Useful energy degenerates to non-useful forms such as thermal
energy to the environment
Adiabatic Processes
• Compression or expansion of a gas where no heat enters or leaves
the system
• If we do work on a system by compression, we heat it up.
• When we expand a system we cool it off
• Remember blowing on your hands?
• Warm air rises, expands, cools and forms clouds
2nd Law of Thermodynamics
• Thermal energy never flows spontaneously from cold object to a hot
object.
• A machine cannot be 100% efficient
• Entropy of closed systems always increases.
• One of the greatest shortcoming of would-be inventors is lack of
understanding of the 1st and 2nd law of Thermodynamics.
Maximum Efficiency of Heat Engine
High Temperature
Input Heat
Work done
Heat Exhaust
Low Temperature
Efficiency
T(K) hot – T(K)cold
Ideal Efficiency = -----------------------T (K)hot
Entropy
• 2nd Law of Thermodynamics
• The entropy of a thermally isolated system never decreases, it can
only increase or stay the same.
• Entropy is a measure of the disorder of a system.
Chapter 19 – Vibrations and Waves
• Summary of Terms
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Sine Wave
Amplitude
Wavelength
Frequency, Hertz
Period
Wave Speed
Longitudinal Wave
Transverse Wave
Interference Pattern
Standing Wave
Doppler Effect
– Bow Wave
– Shock Wave
– Sonic Boom
Waves
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Amplitude - distance from the baseline to the crest of a wave
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Wavelength - the distance from the top of one crest to the top
of the next one
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Period - the time required for one vibration
• measured in seconds
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Frequency - number of vibrations per unit time
• measured in Hertz
Period 
1
Frequency
1
Frequency 
Period
Wave Speed...
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the speed with which waves pass by a particular point
• e.g. the speed of a surfer
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It depends only on the type of medium.
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Wave Speed = Frequency  Wavelength
Transverse Waves
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side to side vibration in a direction perpendicular to the wave's motion
Longitudinal Waves
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back and forth vibration in a direction parallel to the wave's
motion
INTERFERENCE
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Constructive or destructive interference results when waves add.
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Standing Waves - wave pattern produced from interfering waves
– Examples
• Vibrating Strings
• Organ Pipe
Standing Waves
Chapter 20 – Sound
• Summary of Terms
– Infrasonic, Ultrasonic
– Compression, Rarefraction
– Reverberation (echo)
– Refraction (bending)
– Forced Vibration
– Natural Frequency
– Resonance
– Interference
– Beats
SOUND
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infrasonic
– frequencies < 20 Hz
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ultrasonic
– frequencies > 20,000 Hz
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human hearing range
– frequencies between 20 Hz and 20,000 Hz
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Sound requires a medium.
– solid, liquid or gas
Sound waves have compression and rarefaction regions.
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Refraction of Sound
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Refraction - the bending of a wave
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Sound travels faster in warm air than in cool air.
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Sound waves bend toward cooler air.
Sound Interference
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Overlapping compressions of a sound wave will result in…
– …constructive interference.
– …and a louder sound.
Overlapping a compression and a rarefaction results in...
– …destructive interference.
– …and a softer sound.
Beats
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Beats - the periodic variation in loudness of two sounds played together
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The beat frequency is equal to the difference in the frequency of the
two sounds.
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What is the beat frequency when a 262 Hz and a 266 Hz tuning fork
are sounded together?