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Energy and Energy Resources
Energy
• Defined as the ability to do work or the ability
to cause change.
Two types of energy:
• Kinetic energy- energy of motion;
anything that moves has kinetic energy,
cars, balls, and even atoms.
• Potential energy- stored energy;
sometimes called energy of position,
anything not moving has potential
energy
Swinging Pendulum
P.E. is greatest here,
K.E. = 0
P.E. is greatest here,
K.E. = 0
Kinetic energy is
greatest here, P.E. =0
Kinetic energy
• The amount of kinetic energy an object has
depends on two things:
1. mass
2. velocity
K.E. = 1/2mv2
½ (mass X velocity squared)
Potential Energy
• This is the energy that something that is not
moving has the potential of having.
• Potential energy depends on:
1. mass
2. position (height and gravity)
P.E. = mgh (mass X gravity X height)
Forms of energy
•
•
•
•
•
•
Thermal
Chemical
Light
Sound
Electrical
Nuclear
All forms of energy have kinetic and/or potential
energy.
Thermal energy
• Heat energy- all objects have thermal energy;
it increases as temperature increases.
Which has more thermal energy? Why?
Chemical Energy
• Energy stored in chemical bonds; includes the
food we eat.
Light energy
• Form of energy that we see.
Sound energy
• Energy caused by vibrations; some of these
vibrations we can hear.
Electrical energy
• Energy that is carried by an electric current (a
path that electrons follow).
Nuclear Energy
• Energy from the nucleus of an atom
Energy Transformations
• Change from one form of energy to
another.
• Always produces thermal energy (heat).
Examples of energy
transformations
• Photosynthesis (light to chemical)
• Digestion of food (chemical to mechanical)
• Burning of fuel (chemical to mechanical and
thermal)
• Electrical to light and thermal (light bulb)
Law of Conservation of Energy
• States that energy cannot be created or
destroyed, only transferred or changed
from one form to another.
Kinetic and Potential Energy
Kinetic energy and potential energy
can be transferred back and forth as
seen in a swinging pendulum or
throwing a ball up.
Transforming Chemical Energy
• Can be seen as chemical reactions occur
in living things causing bonds to be
broken and kinetic energy (contraction of
a muscle) to be formed.
• Decomposition of dead or decaying
matter.
Transforming Electrical Energy
• Electrical energy can be transformed to
sound energy (listening to the radio)
• Electrical energy can be transformed to
chemical energy (neurons “fire” and
release chemicals)
Transforming Thermal Energy
• Thermal energy can be changed to
mechanical energy (steam used to move
locomotives)
• Thermal energy can be transformed to
light (radiant) energy (glowing metal on
stove)
Generating Electrical Energy
• Generator- device that transforms kinetic
energy into electrical energy
• Turbines- set of steam powered fan
blades that spins a generator at a power
plant.
Electric Power Plants
Power plants- most power plants use
energy from coal to start the
transformation of energy similar to
below.
Chemical
Energy of
Coal
Thermal
Energy of
Water
Kinetic energy
Of turbine
Kinetic
Energy of
Steam
Electrical
Energy
Sources of Energy
Energy that we use comes from two
main sources:
1. Renewable resources- resources that
can be replaced
2. Nonrenewable resources- resources
that cannot be replaced
Nonrenewable Resources
• Fossil Fuels- formed from the
remains of once living things.
- energy from these can be
traced back to the sun through
the food chain
Fossil Fuels- there are three main
types of fossil fuels
• Coal- formed from the remains of plants
that once lived on land
• Petroleum-(crude oil) formed from the
remains of microscopic organisms in the
oceans.
• Natural gas- sometimes found along with
deposits of petroleum; also formed from
ancient ocean microscopic life
Coal
• Primarily used for generating electricity;
also used for paper production and iron
and steel production.
• Coal is mined from deposits in two
methods:
Surface mining
Underground minin
Petroleum
• Refining petroleum produces gasoline,
kerosene, asphalt and petrochemical products
such as plastics; some perfumes and
insecticides are made from products of crude
oil
Natural gas (methane)
• Natural gas is used to heat ( and in some cases
cool) homes and other buildings; also used for
generating electricity
• Burns the cleanest of the fossil fuels
• Can be produced- (by-product of decaying
organic matter)
What’s so bad about these fossil fuels?
1. Energy crisis – result of over
dependence on fossil fuels
2. Burning fossil fuels releases sulfur
dioxide which mixes with rain and
causes acid rain
3. Burning fossil fuels also releases carbon
dioxide which contributes to the
greenhouse effect
Nuclear energy
• Energy from fission (splitting of the atom) can
be converted to other sources of energy such
as electricity
• Negatives- produces radiation that has to be
contained; Uranium is nonrenewable
Renewable Resources
•
•
•
•
•
•
Solar energy
Geothermal energy
Tidal energy
Wind energy
Hydroelectric energy
Biomass
Solar energy- energy from the sun
• Collected by thermal collectors (roofs) or
photovoltaic cells (calculators, roofs, satellites)
Geothermal energy- heat from
deep inside the earth is used as an
energy source
Wind energy- windmills convert kinetic
energy to electrical energy
Hydroelectric energy
• Water that is behind a dam can be used to
move turbines and generate electricity.
Tidal energy
• Energy from the ocean tides can be used to
generate electricity.
Biomass
• Energy from living things (primarily plants) can
be used for fuel.