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Section 1 The Nature of Energy
A. Energy is the ability to cause change.
1. Kinetic energy—Energy in the form of motion.
a. The amount of kinetic energy an object has depends on its mass and its velocity.
b. Kinetic energy = 1/2 mass . velocity2
c. Joule—The SI unit used to measure energy
2. Potential energy—Energy stored in a motionless object, giving it the potential to cause change
3. Elastic potential energy—Energy stored by things that strech or compress.
4. Chemical potential energy—Energy stored in chemical bonds between atoms
5. Gravitational potential energy—Energy stored by things that are above Earth .
a. The amount of GPE an object has depends on its mass , the acceleration due to gravity , and
its height above ground.
b. GPE = mass in kilograms . 9.8 m/s2 . height in meters
Section 2 Conservation of Energy
A. Energy conversions—energy changing from one form to another
1. Fuels store energy in the form of chemical potential energy.
2. Mechanical energy—the total amount of potential and kinetic energy in a system
B. Law of Conservation of Energy—Energy may change from one form to another, but the total amount of
energy never changes.
1. Example—As a swing moves back and forth, its energy continually converts from kinetic to
potential and back.
2. If the energy of the swing decreases, then the energy of some other object must increase by an
equal amount.
3. Friction converts some of the mechanical energy into thermal energy.
C. Converting mass into energy—You must think of mass as energy when discussing nuclear reactions. The
total amount of mass and energy is conserved.
1. Nuclear fusion—Two nuclei are fused together. Takes place in the sun.
2. Nuclear fission—Two nuclei are broken apart.
D. Conservation of energy in your body
1. chemical potential energy from food that is stored in your body is used to fuel the processes that
keep you alive.
2. The food calorie is used to measure how much energy you get from various foods. One
Calorie is equivalent to about 4,180 J.
Section 1 Fossil Fuels
A. Energy cannot be created or destroyed according to the law of conservation of energy, but energy can be
converted from one form to another.
B. Fossil fuels—formed from decaying remains of ancient plants and animals.
1. Burning fossil fuels converts energy from chemical bonds to heat and light.
2. Chemical energy in fossil fuels is more concentrated that in other fuels such as wood.
C. Petroleum—thick, greenish-brown, highly flammable liquid formed by decayed ancient organisms
1. A process called fractional distillation separates the compounds in petroleum.
2. Petroleum is used for plastics, synthetic fabrics, and other products in addition to its useas a fuel.
D. Natural gas is also a product of decayed ancient organisms.
1. It contains more energy per kilogram than petroleum or coal.
2. It burns more cleanly than other fossil fuels.
3. It provides about one-fourth of the energy consumed in the United States.
E. Coal—a solid fossil fuel found underground
1. It produces more pollution when burned than petroleum or natural gas
2. It provides about one-fourth of the energy produced in the United States.
3. About 90 percent of coal burned in the United States is used to produce electricity.
F. Electricity is generated when fossil fuels are burned.
1. The burned fuel releases thermal energy.
2. The thermal energy produces high pressure steam.
3. The steam spins a turbine.
4. The spinning turbine produces an electric current.
5. The electric current is transmitted through power lines to consumers.
G. Only about 35% of the energy in fossil fuel reaches consumers since some energy is lost in every stage of the
H. Fossil fuels have some undesirable side effects.
1. Fossil fuels pollute the environment and increase carbon monoxide in the atmosphere.
2. Mining coal can cause health problems for miners.
I. Fossil fuels are nonrenewable resources, so it is important to not waste energy.
Section 2 Nuclear Energy
A. About 20% of the electricity in the U.S. comes from nuclear power plants.
B. Nuclear reactors contain a fuel, rods to control nuclear reactions, and a cooling system.
1. Heat is produced by nuclear fission—energy is released when U-235 nuclei split in two after being
struck by a neutron.
2. Special rods absorb excess neutrons to prevent dangerous chain reactions.
C. Nuclear power plants use the heat of nuclear fission to produce steam.
1. The steam drives a turbine.
2. The turbine rotates an electric generator.
D. Nuclear power plants produce nuclear waste—radioactive by-products from radioactive materials.
1. Low-level wastes contain only a small amount of radioactive material.
2. High-level wastes must be disposed of extremely carefully because they will remain radioactive
for tens of thousands of years.
E. Nuclear fusion—the joining together of nuclei—is not a practical energy source due to the
high temperature fusion requires.
Section 3 Renewable Energy Sources
A. A renewable resource can be replaced almost as quickly as it is used.
B. Solar energy is converted into electricity by a photovoltaic cell or solar cell.
1. A solar cell converts only 15 to 20 percent of the sun’s energy into electricity.
2. Energy produced by solar cells is more expensive than energy produced with fossil fuels.
3. Energy from solar cells must be stored in batteries when the Sun is not shining.
C. Hydroelectricity is produced by moving water; it is about twice as efficient as fossil fuels or nuclear power.
D. Tidal energy uses moving water, but it can only be used in places where high and low tides are different
E. Windmills can be used to generate electricity, but are useful only when the wind blows consistently.
F. Geothermal energy—thermal energy contained in hot magma; limited to areas where magma is close to the
G. Alternative fuels include hydrogen gas and biomass—renewable organic matter such as wood
or animal manure.
Solids, Liquids, and Gases
Only Section 3 for now.
Chapter 16
Section 3 Behavior of Gases
A. Pressure is measured in units called pascal (Pa).
1. Collisions of particles in air result in atmospheric pressure.
2. Moving particles colliding with the inside walls of a container result in gas pressure.
B. Boyle’s Law—relates pressure and volume
1. Volume decreases as pressure increases.
2. Pressure decreases as volume increases.
3. Pressure multiplied by volume is always equal to a constant if the temperature is constant.
C. Charles’s Law—relates volume and temperature
1. At a constant pressure, volume increases as temperature increases.
2. At a constant pressure volume decreases as temperature decreases.
D. Gay-Lussac’s Law—relates pressure and temperature; at a constant volume, as temperature increases,
pressure increases