What Is Energy?

1
Table of Contents

• What Is Energy?
• Forms of Energy
• Energy Transformations and Conservation
• Energy and Fossil Fuels

2
Exponents
- What Is Energy?

• An exponent tells how many times a number is used
  as a factor. For example, 3 X 3 can be written as
  32. You read this number as three squared. An
  exponent of 2 indicates that the number 3 is used
  as a factor two times. To find the value of a
  squared number, multiply the number by itself.
• 32 3 X 3 9
• Practice Problem
• What is the value of the number 82?

• 64

3
Kinetic Energy
- What Is Energy?

• Kinetic energy increases as mass and velocity
  increases.

4
Potential Energy
- What Is Energy?

• Gravitational potential energy increases as
  weight and height increase.

5

• Elastic Potential Energy
• comes from material snapping back Compression and
  Stretching

6
Using Prior Knowledge
- What Is Energy?

• Before you read, look at the section headings and
  visuals to see what this section is about. Then
  write what you know about energy in a graphic
  organizer like the one below. As you read, write
  what you learn.

What You Know

1. The joule is the unit of work.
2. Energy has different forms.

What You Learned

1. Power is the rate at which energy is transferred.
2. The two basic kinds of energy are potential
   energy and kinetic energy.

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Links on Energy
- What Is Energy?

• Click the SciLinks button for links on energy.

8
End of SectionWhat Is Energy?
9
Calculating Mechanical Energy
- Forms of Energy

• The kinetic energy of a 500-N diver during a dive
  from a 10-m platform was measured. These data are
  shown in the graph.

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Calculating Mechanical Energy
- Forms of Energy

• Reading Graphs
• According to the graph, how much kinetic energy
  does the diver have at 8 m?

• About 1000 J

11
Calculating Mechanical Energy
- Forms of Energy

• Calculating
• Using the graph, find the kinetic energy of the
  diver at 6 m. Then calculate the divers
  potential energy at that point.

• Kinetic energy about 2000 J potential energy
  about 3000 J

12
Calculating Mechanical Energy
- Forms of Energy

• Inferring
• The mechanical energy of the diver is the same at
  every height. What is the mechanical energy of
  the diver?

• About 5000 J

13
Building Vocabulary
- Forms of Energy

• After you read the section, reread the paragraphs
  that contain definitions of Key Terms. Use the
  information you have learned to write a
  definition of each Key Term in your own words.

Key Terms
Examples
mechanical energy
The form of energy associated with the position
and motion of an object is called mechanical
energy.
A type of potential energy called nuclear energy
is stored in the nucleus of an atom.
The sunlight that you see each day is a form of
electromagnetic energy.
thermal energy
The total potential and kinetic energy of the
particles in an object is called thermal energy.
electrical energy
The energy of electric charges is electrical
energy.
chemical energy
Chemical energy is potential energy stored in the
chemical bonds that hold chemical compounds
together.
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Forms of energy
Thermal energy Is the heat energy from vibrating
molecules

• Electrical energy Is the flow of electrons
• .

Chemical energy Is released when old chemical
bonds are broken
Nuclear energy Is the energy released as matter
is converted to other forms of energy
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Forms of energy

• Electromagnetic Energy is light energy. It is
  carried by waves of photons. Photons are given
  off and received by electrons. Includes all the
  wavelengths of light from Radiowaves to Visible
  Light to Gamma Rays.

Mechanical Energy is the combination of kinetic
and Gravitational Potential.
16
Links on Forms of Energy
- Forms of Energy

• Click the SciLinks button for links on forms of
  energy.

17
End of SectionForms of Energy
18
Energy Transformations
- Energy Transformations and Conservation

• Most forms of energy can be transformed into
  other forms.

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Transformations BetweenPotential and Kinetic
Energy
- Energy Transformations and Conservation

• A pendulum continuously transforms energy from
  kinetic to potential energy and back.

20
Asking Questions
- Energy Transformations and Conservation

• Before you read, preview the red headings. In a
  graphic organizer like the one below, ask a
  question for each heading. As you read, write
  answers to your questions.

What is an energy transformation?
An energy transformation is a change from one
form of energy to another.
What are some examples of transformations between
potential and kinetic energy?
Juggling and pendulums show transformations
between potential and kinetic energy.
What is conservation of energy?
The law of conservation of energy states that
energy cannot be created or destroyed.
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• A pendulums period of swing is determined by
  gravity and length of swinging object (ONLY)

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Use of Fossil Fuels
- Energy and Fossil Fuels

• Fossil fuels can be burned to release the
  chemical energy stored millions of years ago.

24
Previewing Visuals
- Energy and Fossil Fuels

• When you preview, you look ahead at the material
  to be read. Preview Figure 18. Then write two
  questions that you have about the diagram in a
  graphic organizer like the one below. As you
  read, answer your questions.

Using Fossil Fuel Energy
Q. What energy transformation occurs in the sun?
A. Nuclear energy to thermal energy and
electromagnetic energy
Q. What energy transformation takes place when
coal is burned?
A. Chemical energy to thermal energy
25
Links on Energy Transformations
- Energy and Fossil Fuels

• Click the SciLinks button for links on energy
  transformations.

26
Use of Fossil Fuels
- Energy and Fossil Fuels

• Click the Video button to watch a movie aboutthe
  use of fossil fuels.

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End of SectionEnergy and Fossil Fuels
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Graphic Organizer
Energy
is the ability to do
exists as
measured in
Kinetic energy
Potential energy
Work
Joules
which at a given rate is
can be
Elastic
Gravitational
Power
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End of SectionGraphic Organizer