Energy forms: PE, KE
Energy types: ME, SE, RE, EE, TE, NE, CE
Energy Sources: biomass, solar, wind, petroleum, geothermal, etc
Energy Types
The seven types of energy are:
ME
mechanical = PE + KE
SE
sound = PE+ KE
CE
chemical = PE
NE
nuclear = PE
TE
RE or LE
EE
thermal = KE
radiant = KE
electrical = KE
ME system = any moving object – pendulum,
ball, gears, bicycle, car, you, etc.
Mechanical energy (ME): the energy of moving
objects; may include either potential or kinetic energy
types, or it may include both at the same time.
When PE is maximum then KE = 0;
When KE is maximum then PE = 0
The mechanical energy of an object can be measured
by adding its potential and kinetic energies together.
The amount of an object’s PE or KE may change, but its
mechanical energy must remain constant. When KE
increases, PE must decrease, or when KE decreases, PE
must increase. ME = PE + KE
If ME is constant and KE
then PE
If ME is constant and KE
then PE
conservation of energy: 1st law of thermodynamics
Energy Types – 2
A pendulum clock is a compound machine that uses
stored energy to do work. A spring stores energy,
and with each swing, some of the PE is converted to
KE to move the hands. At the top of the swing PE is
greatest and KE = 0. At the bottom of the swing, KE
is the greatest and PE = 0. At any time, the PE and
KE can be added to find the total energy of the
system. The
If the KE = 200J and
increases, and the PE
= 200J, what is the
ME? Where is it in its
swing? _____
_____
same concept
applies with
stretching
materials like
PE = Max
PE = Max
springs and
rubber bands.
In a pendulum if the ME =
200J and the KE = 150J
and decreasing, what is
the PE and where is it in
its swing?
_____
_____
A
E
B
C
KE = Max
D
KE – closely spaced particles push
PE – widely spaced particles
Sound = compression wave =
P wave, like dominoes
Why is there no sound in outer space?
Energy Types – 3
speed of sound:
air 68°F = 1130 ft/s, 770 mph;
liquid water = 5000 ft/s, 3409 mph
steel = 20,000 ft/s, 13,636 mph
Sound energy (SE): Vibrating particles transmit
their KE to the resting PE particle next to it. PE and
KE are determined by the spacing or position of the
particles. SE = KE + PE
Sound must have a medium – matter that
carries an energy wave.
Polymer = chains of molecules = plastics, fuels
Chemical energy (CE) is the energy that holds atoms
in molecules together. It is a form of potential energy.
Larger molecules have more chemical energy than
smaller ones. Food and fuel are molecules that break
apart easy, releasing their energy. All stuff has
chemical energy! chemical PE changes into thermal KE + mechanical…
Examples: sugar (carbohydrates), gasoline (hydrocarbons),
ATP (cells), acids/bases - batteries, any type or fuel or food,
all molecules!!!
Carbohydrates:
sugar = C6H12O6
carbs = long sugar chains
fats = long carb chains
Hydrocarbons:
CH4 methane
C3H8 propane
C7 H16 gasoline
C12 diesel/fuel oil
C16 lubricating oil
C20+ asphalt/tar/wax
Most oil/petroleum is turned into plastic not gasoline!
Matter is never lost! It goes somewhere, even if you can’t see it!!
Energy Forms - 4
Where does stuff go when it burns up? Chemical
reactions (breaking of atomic bonds) such as burning
gasoline or digesting food releases the stored chemical
energy and changes it into another form of energy
(usually heat) which leaves the system. Energy is lost
but total mass always stays the same. Combustion
(burning) changes the size and shape but the total mass
is exactly the same before and after.
1st LAW
Thermodynamics
Law of Conservation of Mass:
Mass (matter) cannot be created or destroyed.
mass in (reactants) = mass out (products)
peak oil - point at which
the earth's supply of oil
will no longer be able to
meet our energy needs.
Oil is not a renewable
energy source. It will be
exhausted at some point in
the future.
ANYTHING INTO OIL? Thermal Depolymerization?
ANWR: Arctic National
Wildlife Refuge
Should we drill for oil there?
Neutral carbon sink = no additional carbon put into the atmosphere!
Difference between CE and NE?
CE = molecules; NE = protons and neutrons; NE = most energy of all types
Energy Types - 5
Nuclear energy (NE): the energy that holds protons
and neutrons together inside the nucleus of an atom;
PE; the most powerful energy source every discovered;
produced in two ways:
Nuclear fusion: energy stored in hydrogen
atoms join to form helium releasing large
amounts of electromagnetic energy; our sun
Nuclear fission: the nuclei of large atoms are split
converting the potential nuclear energy into kinetic
electromagnetic energy
Nuclear Reactors?
Nuclear waste/pollution?
no fuel is burned so no air pollution is produced
carbon footprint? NONE! Water is produced!
Uranium fuel rods last about 2-3 years; must be stored until
radioactivity is lost after about ten years – metal recycled!
Nuclear energy is clean and environmentally friendly!!!
Safety? Compare driving vs. flying; nuclear submarines? Japanese
earthquake? Chernobyl? Three Mile island?
Nuclear energy is very safe!
Nonrenewable; 230 years to 1000 yrs?
One pellet the size of your fingertip produces the same amount of
energy as 150 gallons of oil
10 million times as much heat as coal
cold metal versus warm plastic?
endothermic versus exothermic
Energy Types - 6
Thermal energy (TE) is the total
kinetic energy of the particles that make
an object. It is the vibration of all the
atoms or molecules within an object. All
atoms and molecules are in motion at all
times. At room temperature, atoms jiggle
at about 1000 mph. Thermal energy is
measured in joules.
Temperature is a measure
of the average kinetic energy
of the particles in an object.
It is measured in °F or °C or K.
It is the intensity of the
motion of the particles. At
higher temperatures, particles
of matter move faster and
have more kinetic energy. At
lower temperatures, particles
move slower and have lower kinetic energy.
What is the Kelvin scale?
What is absolute zero?
Energy Types - 7
Temperature does not depend on the size
or type of object. For example, the
temperature of a small cup of water might be
the same as the temperature of a large tub of water,
but the tub of water has more thermal energy because
it has more water. High up in the atmosphere, the
temperature increases to over 3600F because gas
molecules absorb solar wind and move very rapidly. But
since the molecules are spaced far apart, the thermal
energy is low even though the temperature (degrees
Fahrenheit or Celsius) is high. The international space station is
here and does not burn up.
Heat is not exactly the same as thermal energy.
Heat is energy that is transferred or moving between
substances due to a temperature difference between
them. The amount of heat transferred by a substance
depends on the speed and number of atoms or
molecules in motion. The faster the atoms or molecules
move, the higher the temperature, and the more atoms
or molecules that are in motion and the greater the
amount of heat they transfer. According to the second
law of thermodynamics, heat
always flows from areas of high
temperature to areas of low
temperature.
Energy Types - 8
Friction is the thermal energy that opposes motion.
It includes the heat given off when things touch. It is
the energy transfer or change from mechanical energy
to thermal energy.
The four states of matter (solid, liquid, gas,
plasma) are scientifically defined by the ratio of a
matter’s used atomic bonds to the number of bonds
possible. Matter states are more easily and commonly
defined:
the amount of chemical and thermal energy
the space between the matter’s molecules
Solid: low energy; molecules are close together; molecules are not
moving fast enough to overcome the attraction of other molecules.
Gas: high amount of energy - too much energy to allow the atoms to
attract and stick much; molecules move fast and are far apart
Liquid: in between a solid and gas; molecules move fast enough to
overcome some of the attraction between them; may change shape but
not volume
Plasma: super high energy; atoms are stripped of their electrons so
they cannot bond together; sun, lightning
Energy Types - 9
Electrical energy (EE) is the movement of electrons
through matter. It is kinetic energy. When electrons
are knocked out of their orbit, electricity is created.
There are two kinds of electricity - static and current.
Static electricity is the random and scattered
movement of electrons in an area where they spread
out. Every time two things touch, they trade electrons
and become ions with either a positive or negative
charge. No work is done in static electricity because
the electrons are scattered. Sometimes the electrons
pile up and form a charge until they find a conducting
path. Lightning is static electricity.
Current electricity is the continuous flow of
electrons along a directed path called a circuit. Since
we control where the electrons go, work is done.
Current always flows from a place where there are
many electrons (negative charge) to a place where
there are fewer electrons (positive charge). This
movement creates a loop. Current always flow from
negative (-) to positive (+). What happens to the magical mystery missing
sock in the cloths dryer?
lightning? electrical safety?
50,000 Volts versus 0.1 Amps – heart attack/death; 0.018A breathing difficulty/suffocation;
0.0001A human perception
Difference between light and sound?
Energy Types - 10
Radiant energy (RE) is the energy from
electromagnetic waves. Electromagnetism is a wave of
pure energy defined by its wavelength and frequency
(the amount of energy in a space). The electromagnetic
spectrum includes radio waves, TV waves, infrared
(heat), visible light, ultra violet, X-rays, gamma rays.
Radiant energy travels at about 186,000 miles per
second in a vacuum (absence of matter - space).
spectrum = range of energy types
Energy Types - 11
Each of the seven forms of energy can be changed into
any one of the other energy forms. A change in energy form
is called an energy conversion. All energy comes from other
forms of energy. This is the first law of thermodynamics.
Examples: light energy from the sun can
be converted into heat energy by the
ground and into chemical energy stored in
sugar by photosynthesis in plants; a
battery may convert chemical energy into
electrical energy; a stereo may convert
electrical energy into sound energy using
the speakers; a combustion engine
converts chemical energy from the
gasoline into mechanical energy which
pushes the piston down.
Energy conversions often
involve the changing or movement of matter. There are three
types of objects or areas where matter and energy
conversions take place (isolated, closed, open). A system is a
place or object where matter and energy exist and energy
conversions take place over a certain period of time.
Systems often exist inside other systems. For
example: nervous, cardiovascular, respiratory,
muscle, and skeletal systems all operate
together inside the human body system. A
machine is a man-made system that makes work
easier by changing the size or direction of the
force.
Energy Types - 12
Systems try to control the type of energy
conversions that happen in order for them to do work.
But, not all the energy in a conversion in a system
becomes useful energy. Any time that things touch,
they trade energy and heat is lost which is wasted
energy. In totally 100% efficient systems, all the
energy put in does exactly what was intended and is
useful. Because parts in a system must touch and trade
heat, no system can ever be 100% efficient.
THREE SYSTEMS:
Isolated system:
an exchange or transfer of matter and energy only within the
system and none outside to the surrounding - everything
stays in and stays out.
these are impossible because they violate the first law of
thermodynamics - everything must touch and trade heat
so nothing can be totally isolated and 100% efficient!
There are no isolated systems inside the universe; the only
known isolated system is the universe itself as whole.
The main goal of all engineering is to get as close as
possible to an isolated system or 100% efficient.
Energy Types - 13
Closed system:
an exchange or transfer of matter and energy
within the system, and where there is no
transfer of matter outside, but there is some exchange
of energy outside the system - heat is given off.
they will eventually run out of energy or fuel.
most created machines and most natural or biological
systems are considered to be closed at least for periods
of time.
Examples: a bouncy ball, a battery circuit, cars and airplanes
(after refueling not during), animals (not including
breathing, after eating a meal not during).
Open system:
transfer of both matter and energy both inside and outside
different systems - matter and energy enter and leave
the system.
Most machines are not open because there would need to
be constant change in either the amount of work being done
or a constant refueling/feeding process; resources are
renewed and exchanged on a regular basis.
Examples: refrigerator or electric appliances – something
constantly plugged in, volcanoes, hurricanes, tornadoes,
weather fronts, solar system, ecosystems, water cycle.
PEAK OIL
World discovery of oil peaked in the 1960s, and has declined since then. If the
40 year cycle seen in the US holds true for world oil production, that puts
global peak oil production, right about now; after which oil becomes less
available, and more expensive.
Today we consume around 4 times as much oil as we discover.
If we apply Hubbert's Peak to world oil production we estimate that
approximately half of all oil that will be recovered, has been recovered, and oil
production may reach a peak in the near future, or perhaps already has.
http://peakoil.com/what-is-peak-oil/
HYDROCARBONS
In a 42 gallon
barrel of crude oil
20 gal
0.2 gal
4 gal
9 gal
0.5 gal
2 gal
6 gal
Equivalent Resistance:
1/Req = 1/R1 + 1/R2 + 1/R3
1/Req = 1/(5.0 ) + 1/(7.0 ) + 1/(12
1/Req = 0.42619 -1
Req = 1 / (0.42619 -1)
Req = 2.3
)
ELECTRICAL SAFETY
As shown in the chart, shock is relatively more severe as the current rises. For
currents above 10 milliamps, muscular contractions are so strong that the victim
cannot let go of the wire that is shocking him. At values as low as 20 milliamps,
breathing becomes labored, finally ceasing completely even at values below 75
milliamps. As the current approaches 100 milliamps, ventricular fibrillation of the
heart occurs - an uncoordinated twitching of the walls of the heart's ventricles which
results in death. Above 200 milliamps, the muscular contractions are so severe that
the heart is forcibly clamped during the shock. This clamping protects the heart from
going into ventricular fibrillation, and the victim's chances for survival are good.