Section One: What is energy? (pg. 374)

•Energy is the ability to cause change

•Any time a change occurs, energy is transferred from one object to another

Section One: What is energy? (pg. 375)

• Kinetic energy is the energy an object has due to its motion. If an object isn’t moving, it does not have kinetic energy.

• A faster ball causes more change to occur than a ball that is moving slowly

• Kinetic energy increases as an object moves faster

• Kinetic energy increases as the mass of the object increases (see volleyball/bowling ball example- pg. 375)

Section One: What is energy? (pg. 376)

• Potential energy is the energy stored in an object because of its position.

• Potential energy increases as the mass and height of the object increases.

Section One: What is energy? (pg. 376)

• Thermal energy is the sum of the kinetic and potential energy of the particles in a material

• Thermal energy increases as temperature increases. (hot chocolate vs cold water- pg 376)

• Our bodies produce thermal energy; thermal energy released by chemical reactions come from chemical energy

Section One: What is energy? (pg. 376)

• Chemical energy is the energy stored in chemical bonds. When chemicals are broken apart and new chemicals are formed, some of this energy is released. (candle burning example pg. 377)

Section One: What is energy? (pg. 377)

• .

• When light strikes something it can be absorbed, transmitted or reflected.

When light is absorbed by an object and the object becomes warmer, the energy is transformed into thermal energy.

• Radiant energy is the energy carried by light.

Section One: What is energy? (pg. 379)

.• Electrical energy is energy carried by an electric current.

About 20% of the electrical energy used in the United States is generated by nuclear power plants.

• Nuclear energy is energy contained in atomic nuclei.

• Releasing nuclear energy is difficult and can only be released through complex power plants.

Section Two: Energy Transformations (pg 379)

Mountain biker climbing a hill: kinetic energy of the bike and riderpotential energy as he moves up the hillchemical energy in the rider’s musclesthermal energy

.

Section Two: Energy Transformations (pg 379)

The Law of Conservation of Energy: energy is never created or destroyed. The only thing that changes is the form in which the energy appears

.

Section Two: Energy Transformations (pg 380)

Changing Kinetic and Potential Energyex:Tossing a ball in the air; as the ball leaves your hand, most of its energy is kinetic. As it rises, its kinetic energy decreases but is replaced by an increase in potential energy as the ball flies higher in the air.The total amount of energy remains constant.

.

Section Two: Energy Transformations (pg 381)

Transforming chemical energyThe matter contained in living organisms (biomass) contains chemical energy. Chemical energy transforms into thermal energy.

.

Section Two: Energy Transformations (pg 383)

Transforming electrical energyRadio example (pg. 383):Electrical energy to kinetic energy of speakers to sound energy of air to kinetic energy of eardrum and fluid to electrical energy of brain and nerve cells.

.

Section Two: Energy Transformations (pg 383)

Transforming thermal energy

Thermal energy can be transformed into kinetic energy (for example steam engines)

Thermal energy can be transformed into radiant energy (for example when a bar of metal is heated to a high temperature, it glows and gives off light)

.

Section Two: Energy Transformations (pg 384)

Thermal energy movesThermal energy can move from one place to another.

Thermal energy only moves from something at a higher temperature to something at a lower temperature.

Section Two: Energy Transformations (pg 384)Generating Electrical Energy A generator is a device that transforms kinetic energy into electrical energy; a generator converts the kinetic energy of a spinning turbine into electrical energy.

turbine- set of steam-powered fan blades that spins a generator at a power plant.

Section Two: Energy Transformations (pg 385)Section Questions

Section 3: Sources of Energy

• All of the energy we use can be traced to the Sun or to radioactive atoms in the Earth’s interior

• The amount of energy Earth receives from the Sun is far greater than the amount generated in Earth’s interior

• Nearly all of the energy we use today can be traced to the Sun

Section 3: Sources of Energy

• Fossil fuels are coal, oil, and natural gas

• Fossil fuels are nonrenewable resources. A nonrenewable resource is an energy source that is used up much faster than it can be replaced.

Section 3: Sources of Energy

Nuclear Energy (pg.389)

• To obtain electrical energy from nuclear energy, a series of energy transformations must occur. (figure 18- pg. 389)

• Nuclear energy is a nonrenewable resource

• Nuclear energy has advantages and disadvantages. Ex: The waste produced by nuclear power plants is radioactive and can be dangerous to living things.

Section 3: Sources of Energy

Hydroelectricity

• Renewable resource is an energy source that is replenished continually

• Hydroelectricity (the potential energy of water that is trapped behind dams) is the largest renewable source of energy.

• Advantage: largely pollution free• Disadvantage: disrupts the life cycle of aquatic life

Section 3: Sources of Energy

Alternative Sources of Energy

• New sources of energy that are safer and cause less harm to the environment are called alternative resources such as wind, solar energy, and geothermal energy.

Solar Energy• solar power• An inexhaustible resource is an energy source that can’t be used up

by humans. The Sun is an inexhaustible source of energy because it will go on producing energy for billions of years.

• Solar energy is more expensive to use than fossil fuels• Solar energy can be collected and utilized by individuals using

thermal collectors or photovoltaic collectors.

• geothermal energy

Section 3: Sources of Energy

Energy from the Oceans

Using Tidal Energy

Tidal Energy

Tidal energy is he energy obtained from the rise and fall of the tides.

Tidal turbines act like underwater windmills.

Tidal barrages are special dams that take advantage of the difference between high and low tides.

Advantage: inexhaustible resource

Disadvantages: High costOnly in a few places is the difference between high and low tides large enough to enable a large electric power plant to be built

Section 3: Sources of Energy

Wind

WInd energy

Wind is a renewable energy resource.

Kinetic energy is converted into electrical energy

Section 3: Review Questions

1. Diagram the energy conversions that occur when coal is formed, then burned produce thermal energy. Radiant energy from the sun is converted into chemical energy when coal is formed; chemical energy in coal is converted into thermal energy and radiant energy when coal is burned.

2. Explain why solar energy is considered an inexhaustible source of energy. The sun’s energy cannot be used up by humans because the sun will produce an enormous amount of energy for billions of uears and humans can use only a small amount of the energy the Sun produces.

3. Explain how a heat pump is used to both heat and cool a building The ground at several meters’ depth is cooler than the outside air in summer and warmer than the outside air in winter. Heat can be transferred from the building to the ground in summer, and from the ground to the building in the winter.

4. Identify advantages and disadvantages of using fossil fuels, hydroelectricity and solar energy as energy sources.