Chapter 13

Energy

Ch 13.1 – What is Energy?

A. Energy is the ability to do work and cause change

B. Kinetic energy is energy of motion

1. Kinetic energy increases as an object moves faster

2. Kinetic energy increases as the mass of an object increases

C. Potential Energy – energy stored in an object due to its position

1. Potential energy increases with height

2. Potential energy increases with mass

D. Energy comes in different forms

1. Thermal Energy – heat energy; increases as temperature increases; higher the thermal energy the faster the atoms move

2. Chemical Energy – energy stored in chemical bonds of atoms; body breaks down chemical bonds in food to release that energy

3. Radiant Energy – light energy; travels 300,000km/s; can circle Earth 8 times/second

a) May be absorbed, transmitted or reflected

b) Absorbed light energy becomes thermal energy

4. Electrical Energy – energy from electricity = flowing electrons; examples include lightening and the energy moving through wires of appliances

5. Nuclear Energy – contained within the nucleus of an atom holding together the protons and neutrons; can be released in nuclear power plants to generate electricity

Ch 13.2 – Energy Transformations

A. Energy is constantly changing from one form to another

B. Law of Conservation of Energy – energy is never created or destroyed; it merely changes from one form to another

C. Energy can be transferred from kinetic to potential and back to kinetic

a) Ex: tossing a ball up in the air

D. Machines transform energy from one form to another

1. Chemical energy can be transferred to kinetic, radiant or thermal

2. Electrical energy can be transformed to kinetic, chemical, electrical or thermal

3. A turbine’s kinetic energy is converted to electrical energy by a generator at a power plant

Chemical energy Thermal energy Kinetic energy Kinetic energy Electricalof coal of water of steam of turbine out of generator

4. Unlike other forms of energy, thermal energy is not easy to store because it is constantly moving from areas of higher amounts to lesser amounts

Ch 13.3 – Sources of Energy

A. All energy comes from the Sun or radioactive atoms inside the Earth

B. Fossil Fuels – energy resources formed from ancient decaying organisms over millions of years

1. Include coal, oil & natural gas

2. Fossil fuels contain the chemical energy originally from the Sun via photosynthesis

3. Considered nonrenewable resources because they are being used up faster than replaced

a) Coal reserve 200-300 more years

b) Oil & Natural Gas reserves 30-60 years

4. Pollution is caused by burning fossil fuels (in cars, factories etc.)

a) Acid Rain – caused from gases released by burning coal or oil which mix with water vapor in the air

C. Alternate (Inexhaustible) Energy Resources

1. Solar Energy – energy from the Sun

a) Solar energy can be captured in photovoltaic cells and be converted into electricity

b) The Sun produces enough energy in 15 minutes to provide world with electricity for a whole year

2. Wind Energy – uses windmills (windfarms)

a) Can generate electricity without pollution

b) Wind not steadily available in all locations

3. Hydroelectric Energy – from water

a) Dams make use of potential energy

4. Geothermal Energy – thermal energy of magma beneath Earth’s surface

5. Nuclear Energy – produced by splitting nuclei

a) Element used in power plants is uranium

b) Process of splitting nuclei is fission

D. Energy Conservation

1. We must help conserve energy in order to prevent shortages and allow fossil fuels to last longer

The End

Forms of Energy

Electrical

Solar

Chemical

Nuclear

Geothermal

Kinetic

Potential

Produced by Power Plants

Comes from The Sun

Located in

Located in

Chemical bonds

Atom’s nuclei

Comes from

Magma

Is energy of…

Is energy of…

Motion

Position