Download Energy - Kawameeh Middle School

Do you agree or disagree?
1. An object sitting on a high shelf has
no energy.
2. There are many forms of energy.
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?
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.
• Some examples of potential energy are:
objects that could fall due to gravity. And
particles that can move because of
electric or magnetic forces.
With your group come up
with 5 more examples of
potential energy
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.
– meaning that if two objects are traveling at
the same speed, the one with more mass
will have more kinetic energy
• The energy in an electric current is
electric energy.
Kinetic Energy (cont.)
Talk to your partners:
How do potential energy and
kinetic energy differ?
Kinetic Energy (cont.)
How do potential energy and
kinetic energy differ?
Answer: Potential energy is
stored, and kinetic energy is
energy due to motion.
What kind of energy is shown here?
• Is kinetic energy shown
here?
• Is potential energy shown
here?
• Explain both.
Combined Kinetic Energy and
Potential Energy
The sum of the potential energy and the
kinetic energy in a system is mechanical
energy.
The hockey player on the last slide showed both
potential and kinetic energy. Therefore the puck
had mechanical energy.
Come up with an example of something that has
mechanical energy with your partners.
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.)
What is the same and what is
different about mechanical
energy and thermal energy?
Combined Kinetic Energy and
Potential Energy (cont.)
What is the same and what is
different about mechanical
energy and thermal energy?
Answer: Both are sums of potential and
kinetic energy. Thermal is the sum of the
particles in an object, and kinetic is the sum
of the parts in a system.
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.
• Light is a form of energy carried by
electromagnetic waves, which are electric and
magnetic waves moving perpendicular to one
another.
• 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.
• 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.
1. 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
2. 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
3. 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.
Click for Review of Concepts
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
What do you think?
Do you agree or disagree?
1. In most systems, no energy is
transferred to the environment.
2. Some forms of energy are replenished
naturally.
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.
In every energy transformation, some
energy transfers to the environment.
The 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.)
• 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.
• Come up with your own example of an
energy transfer with your partners
Law of Conservation of Energy (cont.)
• When one form of energy is converted
to another form of energy, an energy
transformation occurs. (click me)
• 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.
• Come up with your own example of an energy
transformation with your partners.
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.)
Identify an energy transfer and an
energy transformation that occurs
when someone plays a guitar.
Answer: Chemical energy in the cells is
transformed to mechanical energy in the
fingers, then transferred to the guitar strings.
Electric energy from the amp is converted into
sound energy when the chords are struck.
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.
• If a tennis player is holding a tennis ball
before a serve, is she doing work on the
ball?
– Recall that to do work a force must be
working on an object.
• Come up with an example of work being
done in your everyday life, with your
partners.
• Anytime there is an energy transformation
or energy transfer, some energy is
transformed into thermal energy.
• Energy transformations are inefficient
because not all the energy that is
transformed to another form of energy is
usable.
• Lets go back to the flashlight. In a
flashlight the transformation of chemical
energy from the battery to radiant energy
from the light bulb is inefficient. As the
electric energy move through the circuit,
some electric energy transforms to thermal
energy. This makes the transformation
inefficient, and this is why some bulbs are
warm.
• With your partners: Explain the above
transformation and why its inefficient.
Law of Conservation of Energy (cont.)
• An open system is a system that
exchanges matter or energy with the
environment.
• 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.
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. (click me)
• 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 Transformations and
Electric Energy (cont.)
What are renewable and
nonrenewable energy resources?
Renewable: energy resource that is replaced
as fast or fast than it is used
Nonrenewable: energy resource that is
available in limited amounts or is used faster
than can be replaced in nature
• 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.
1. Which term refers to 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
2. A car’s engine is an example of
which of these?
A. closed system
B. energy resource
C. geothermal energy
D. open system
3. 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?
1. In most systems, no energy is
transferred to the environment.
2. Some forms of energy are replenished
naturally.