Chapter Introduction
Lesson 1 Forms of
Energy
Lesson 2 Energy
Transfers and
Transformations
Lesson 3 Particles
in Motion
Chapter Wrap-Up
What is the difference
between energy transfers
and energy
transformations?
What do you think?
Before you begin, decide if you agree or
disagree with each of these statements.
As you view this presentation, see if you
change your mind about any of the
statements.
Do you agree or disagree?
1. An object sitting on a high shelf has
no energy.
2. There are many forms of energy.
3. In most systems, no energy is
transferred to the environment.
Do you agree or disagree?
4. Some forms of energy are replenished
naturally.
5. Only particles that make up moving
objects are in motion.
6. Thermal energy can be transferred in
several ways.
Forms of Energy
• How do potential energy and kinetic
energy differ?
• How are mechanical energy and
thermal energy similar?
• What two forms of energy are carried
by waves?
Forms of Energy
• energy
• potential energy
• chemical energy
• nuclear energy
• kinetic energy
• electric energy
• mechanical
energy
• thermal energy
• wave
• sound energy
• radiant energy
Energy
• Energy influences everything in your
life, including the climate, the economy,
and your body.
• Scientists define energy as the ability
to cause change.
Potential Energy
• Potential energy is stored energy due
to the interaction between objects or
particles.
• Objects have potential energy if they
have the potential to cause change.
Objects have gravitational potential energy
if they have mass and height above
Earth’s surface.
Potential Energy (cont.)
• Chemical energy is the energy stored in
and released from the bonds between
atoms.
• Your body breaks chemical bonds in
foods and coverts the released energy
into other forms of energy that your body
can use.
Potential Energy (cont.)
• The energy stored in and released from
the nucleus of an atom is called nuclear
energy.
• The Sun’s energy is released through
the process of nuclear fusion, during
which the nuclei of atoms join together
and release large amounts of energy.
Kinetic Energy
• Kinetic energy is energy due to motion.
• An object’s kinetic energy is related to
the mass and the speed of the object.
• The energy in an electric current is
electric energy.
Kinetic Energy (cont.)
How do potential energy and
kinetic energy differ?
Combined Kinetic Energy and
Potential Energy
The sum of the potential energy and the
kinetic energy in a system is mechanical
energy.
mechanical
from Greek mēchanē, means
“machine”
Combined Kinetic Energy and
Potential Energy (cont.)
• An object’s thermal energy is the sum
of the kinetic energy and the potential
energy of the particles that make up the
object.
• Thermal energy of an object increases
when the potential energy, the kinetic
energy, or both increase.
Combined Kinetic Energy and
Potential Energy (cont.)
Compare mechanical energy
and thermal energy.
Energy Carried by Waves
• A wave is a disturbance that transfers
energy from one place to another without
transferring matter.
• Sound energy is carried by sound
waves.
• The energy carried by electromagnetic
waves is radiant energy.
Electromagnetic waves often are
described by their wavelengths—the
distance from one point on a wave to the
nearest point just like it.
Visible light is one form of radiant energy.
Energy Carried by Waves (cont.)
What two forms of energy are
carried by waves?
• Objects can have potential energy
(stored energy) and kinetic energy
(energy due to movement).
• Mechanical energy is due to largescale motions and interactions in a
system. Thermal energy is due to
atomic-scale motions and interactions
in particles.
• Two kinds of energy carried by waves
are sound energy and radiant energy.
Which term describes energy
stored in and released from the
bonds between atoms?
A. chemical energy
B. kinetic energy
C. mechanical energy
D. nuclear energy
Which refers to a disturbance that
transfers energy from one place
to another without transferring
matter?
A. wave
B. wavelength
C. potential energy
D. thermal energy
What type of energy provides the
warmth from the Sun?
A. chemical energy
B. nuclear energy
C. potential energy
D. radiant energy
Do you agree or disagree?
1. An object sitting on a high shelf has no
energy.
2. There are many forms of energy.
Energy Transfers and
Transformations
• What is the law of conservation of
energy?
• How is energy transformed and
transferred?
• What are renewable and
nonrenewable energy resources?
Energy Transfers and
Transformations
• law of
conservation
of energy
• energy transfer
• energy
transformation
•
•
•
•
work
open system
closed system
renewable energy
resource
• nonrenewable
energy resource
Law of Conservation of Energy
The law of conservation of energy says
that energy can be transformed from one
form to another, but it cannot be created or
destroyed.
The law of
conservation of
energy indicates that
the amount of radiant
energy that shines out
of the flashlight cannot
be greater than the
chemical energy
stored in the battery.
Law of Conservation of Energy (cont.)
What is the law of conservation
of energy?
Law of Conservation of Energy (cont.)
• When energy moves from one object
to another without changing form, an
energy transfer occurs.
• The mechanical energy of a tennis
racket changing the movement of the
ball is an example of an energy transfer.
Law of Conservation of Energy (cont.)
• When one form of energy is converted
to another form of energy, an energy
transformation occurs.
• The conversion of chemical energy
stored in a tennis player’s muscle
changing to mechanical energy when
she swings her arm is an example of an
energy transformation.
Law of Conservation of Energy (cont.)
Identify an energy transfer and an
energy transformation that occurs
when someone plays a guitar.
Law of Conservation of Energy (cont.)
• To a scientist, work is the transfer of
energy that occurs when a force makes
an object move in the direction of the
force. Work is only being done while the
force is acting on the object.
• Any time there is an energy
transformation or energy transfer, some
energy is transformed into thermal
energy.
Law of Conservation of Energy (cont.)
• Because energy transformations are
inefficient, some of the chemical energy
transforms to thermal energy and sound
energy that are released to the
environment.
• An open system is a system that
exchanges matter or energy with the
environment.
Law of Conservation of Energy (cont.)
• A closed system is a system that does
not exchange matter or energy with the
environment.
• In reality, there are no closed systems
because every physical system transfers
some energy to or from its environment.
Law of Conservation of Energy (cont.)
system
from Greek systema, means
“whole made of several parts”
Energy Transformations and
Electric Energy
• A renewable energy resource is an
energy resource that is replaced as fast
as, or faster than, it is used.
• Solar energy from the Sun is one type of
renewable energy resource that can be
converted into electric energy.
Energy Transformations and
Electric Energy (cont.)
• Wind moves the blades of a wind turbine
to generate electric energy.
• In hydroelectric plants, falling water is
channeled through a turbine which
transforms mechanical energy into
electric energy.
Energy Transformations and
Electric Energy (cont.)
• Geothermal plants transfer thermal
energy from the Earth to water, creating
steam that turns turbines in electric
generators.
• Biomass includes wood, plants, manure,
and garbage, all of which are sources of
stored chemical energy that can be
transformed to electric energy in energy
plants.
Energy Transformations and
Electric Energy (cont.)
• Nonrenewable energy resources are
energy resources that are available in
limited amounts or that are used faster
than they can be replaced in nature.
• Fossil fuels include petroleum, natural
gas, propane and coal.
• In nuclear energy plants, uranium atoms
are split apart in a process called nuclear
fission.
Most of the energy used in the United
States comes from nonrenewable energy
resources.
Energy Transformations and
Electric Energy (cont.)
What are renewable and
nonrenewable energy resources?
• Energy can be transferred and
transformed, but it cannot be created
or destroyed.
• Systems are classified as open
systems or closed systems based on
their interactions with their
environment.
• Energy resources are classified as
renewable or nonrenewable based
on their abundance and availability.
Which term refers the transfer of
energy that occurs when a force
makes an object move in the
direction of the force?
A. conservation
B. work
C. closed system
D. open system
A car’s engine is an example of
which of these?
A. closed system
B. energy resource
C. geothermal energy
D. open system
Which is an example of biomass?
A. open system
B. solar energy
C. nonrenewable energy resource
D. renewable energy resource
Do you agree or disagree?
3. In most systems, no energy is
transferred to the environment.
4. Some forms of energy are replenished
naturally.
Particles in Motion
• What is the kinetic molecular theory?
• In what three ways is thermal energy
transferred?
• How are thermal conductors and
insulators different?
Particles in Motion
• temperature
• convection
• heat
• vaporization
• conduction
• thermal conductor
• radiation
• thermal insulator
Kinetic Molecular Theory
• The kinetic molecular theory explains
how particles move and has three major
points:
• All matter is made of particles.
• Particles are in constant, random
motion.
• Particles constantly collide with each
other and with the walls of their
container.
Particles that make up all matter are in
constant motion. On average, solid particles
move slowest, liquid particles move faster,
and gas particles move the fastest.
Kinetic Molecular Theory (cont.)
What are the three points of the
kinetic molecular theory?
Kinetic Molecular Theory (cont.)
• The measure of the average kinetic
energy of the particles in a material is
temperature.
• When the particles that make up a
material move slowly, they occupy less
volume than they do at a higher
temperature.
• Thermal expansion is the increase in
volume of a material due to a
temperature increase.
Kinetic Molecular Theory (cont.)
When water is cooled to near its freezing
point, interactions between water
molecules push the molecules apart.
Kinetic Molecular Theory (cont.)
• As the kinetic energy of the particles
that make up a material increases,
the thermal energy of the particles
increases.
• As the kinetic energy of the particles
that make up a material decreases,
the thermal energy of the particles
decreases.
When you put a warm bottle of water in a
cold refrigerator, thermal energy is
transferred.
Kinetic Molecular Theory (cont.)
• The movement of thermal energy from a
region of higher temperature to a region
of lower temperature is called heat.
• When the temperatures of materials
that are in contact are the same, the
materials are said to be in thermal
equilibrium.
Kinetic Molecular Theory (cont.)
equilibrium
from Latin aequus, means
“equal”; and libra, means
“a balance or scale”
Heat Transfer
• Conduction is the transfer of thermal
energy by collisions between particles in
matter.
• Radiation is the transfer of thermal
energy by electromagnetic waves.
• Convection is the transfer of thermal
energy by the movement of the particles
from one part of a material to another.
Conduction, radiation, and convection
are ways in which thermal energy is
transferred.
Heat Transfer
(cont.)
In what three ways is thermal
energy transferred?
Heat and Changes of State
• Melting is the change of state from a
solid to a liquid.
• Freezing is the change of state from a
liquid to a solid.
Heat and Changes of State
(cont.)
• Vaporization is the change of state from
a liquid to a gas.
• Vaporization that occurs within a liquid is
called boiling.
• Vaporization that occurs at the surface of
a liquid is called evaporation.
Heat and Changes of State
(cont.)
• Sublimation is the change of state that
occurs when a solid changes to a gas
without passing through the liquid state.
• Deposition is the change of state from a
gas directly to a solid without passing
through the liquid state.
• Water vapor undergoes deposition when
it freezes and forms frost.
Heat and Changes of State
(cont.)
sublime
Science Use to change from a solid
state to a gas state without passing
through the liquid state
Common Use inspiring awe; supreme,
outstanding, or lofty in thought or
language
Conductors and Insulators
• A thermal conductor is a material in
which thermal energy moves quickly.
• A thermal insulator is a material in
which thermal energy moves slowly.
Conductors and Insulators (cont.)
How do thermal conductors differ
from thermal insulator?
• The kinetic molecular theory explains
how particles move in matter.
• Thermal energy is transferred in
various ways by particles and waves.
• Materials vary in how well they
conduct thermal energy.
Which term refers to the transfer
of thermal energy between
particles in matter?
A. conduction
B. convection
C. heat
D. radiation
Which describes the transfer of
thermal energy by the movement
of particles from one part of a
material to another?
A. conduction
B. convection
C. radiation
D. vaporization
What is the change of state from
a gas directly to a solid without
passing through the liquid state?
A. deposition
B. melting
C. sublimation
D. vaporization
Do you agree or disagree?
5. Only particles that make up moving
objects are in motion.
6. Thermal energy can be transferred in
several ways.
Key Concept Summary
Interactive Concept Map
Chapter Review
Standardized Test Practice
Energy is involved in all
physical processes; it is
transferred when it
moves from object to
object without changing
form. Energy is
transformed when it is
converted to another
form. Energy is
conserved during
transfers and
transformations.
Lesson 1: Forms of Energy
• Potential energy is stored energy,
and kinetic energy is energy
of motion.
• Both mechanical energy and
thermal energy involve kinetic
energy and potential energy.
Mechanical energy is the sum of the kinetic energy
and the potential energy in a system of objects.
Thermal energy is the sum of the kinetic energy and
the potential energy in a system of particles.
• Sound energy and radiant energy are carried by
waves.
Lesson 2: Energy Transfers and
Transformations
• The law of conservation of energy says that
energy can be transformed from one form to
another, but it cannot be created or destroyed.
• Energy is transformed when it is converted
from one form to another. It is transferred
when it moves from one object to another.
• Renewable energy resources are resources
that are replaced as fast as, or faster than
they are used. Nonrenewable energy resources are
resources that are available in limited quantities or
are used faster than they can be replaced.
Lesson 3: Particles in Motion
• The kinetic molecular theory says
that all objects are made of
particles; all particles are in
constant, random motion; and the
particles collide with each other
and with the walls of their container.
• Thermal energy is transferred by conduction,
radiation, and convection.
• A thermal conductor transfers thermal energy easily
and a thermal insulator does not transfer thermal
energy easily.
Which describes the sum of the
potential energy and the kinetic
energy in a system?
A. mechanical energy
B. nuclear energy
C. sound energy
D. thermal energy
Which refers to energy due to
motion?
A. electric energy
B. kinetic energy
C. potential energy
D. radiant energy
Which term refers to an energy
resource that is replaced as fast
as, or faster than, it is used?
A. fossil fuel
B. natural gas
C. nonrenewable energy resource
D. renewable energy resource
Which term refers to a system
that exchanges matter or energy
with the environment?
A. closed system
B. energy resource
C. open system
D. solar energy
Which refers to the movement of
thermal energy from a region of
higher temperature to a region of
lower temperature?
A. conduction
B. deposition
C. heat
D. vaporization
Which term refers to the ability to
cause change?
A. energy
B. heat
C. wave
D. work
If an object has mass and height
above Earth’s surface, what type
of energy does it have?
A. gravitational potential energy
B. kinetic energy
C. nuclear energy
D. radiant energy
What type of energy is stored in
and released from the nucleus of
an atom?
A. chemical energy
B. nuclear energy
C. radiant energy
D. thermal energy
Which term refers to energy
resources that are available in limited
amounts or that are used faster than
they can be replaced in nature?
A. energy transfer
B. solar energy
C. nonrenewable energy resources
D. renewable energy resources
Which is a material in which
thermal energy moves slowly?
A. radiation
B. kinetic energy
C. thermal conductor
D. thermal insulator