Unit 3 – Energy!
S8P2. Students will be familiar with the forms and
transformations of energy.
a. Explain energy transformation in terms of the Law of
Conservation of Energy.
b. Explain the relationship between potential and kinetic
energy.
c. Compare and contrast the different forms of energy
(heat, light, electricity, mechanical motion, sound) and
their characteristics.
d. Describe how heat can be transferred through matter
by the collisions of atoms (conduction) or through space
(radiation). In a liquid or gas, currents will facilitate the
transfer of heat (convection)
Essential Question
How are ENERGY, WORK,
and POWER related?
What is Energy? P.442
• Discover Activity:
1. Hold a meter stick vertically with the zero end on the
ground.
2. Drop a tennis ball from the 50-cm mark and record the
height to which it bounces.
3. Drop the tennis ball from the 100-cm mark and record the
height to which it bounces.
4. Predict how high the ball will bounce if dropped from the
75-cm mark. How did you make this prediction?
5. Test your prediction.
6. Conclude – How does the height from which you drop the
ball relate to the height to which the ball bounces?
What is Energy? P.442
• Work is done when a force moves an object
through a distance
• The ability to do work or cause change is
called energy.
• Work is the transfer of energy; work and
energy are measured in joules.
• If the transfer of energy is work, then power is
the rate at which energy is transferred, or the
amount of energy transferred in a unit of
time.
Power = Energy transferred
time
• Power is involved whenever energy is
being transferred.
Kinetic Energy
• Moving objects do work, so they have energy.
• The energy an object has due to its motion is called
kinetic energy.
• Kinetic energy of an object depends on its mass and
its velocity – KE increases as mass increases. KE
also increases as velocity increases.
• Recall the meanings of mass and velocity:
Mass = A measure of how
much matter is in an
object.
Velocity – Speed in
a given direction.
Calculating Kinetic Energy
Kinetic energy = ½ x Mass x Velocity2
• Changing the velocity of an object will
have a greater effect on its kinetic
energy than changing its mass by the
same factor because velocity is
squared.
Potential Energy
• Stored energy that results from the position or
shape of an object is called potential energy.
• This type of energy has the potential to do work.
Let’s see an example of
Kinetic and Potential
Energy at work!
Gravitational Potential Energy
• is related to an object’s
height, and is equal to
the work done to lift it.
• The more an object
weighs, or the greater
the object’s height, the
greater its GPE
GPE = Weight x Height
Elastic Potential Energy
• Is the potential
energy associated
with objects that
can be stretched,
or compressed.
Roadrunner Energy Video Link
Energy Skate Park
• Yes, even Bill loves to
demonstrate Kinetic
and Potential energy!
Can You ANSWER the
Essential Question?
How are ENERGY, WORK,
and POWER related?
Essential Question:
• Differentiate between kinetic
and potential energy.
Warm-Up: Venn Diagram
Gravitational
Potential Energy
Elastic Potential
Energy
Standard: S8P2c
• Compare and contrast the
different forms of energy
(heat, light, electricity,
mechanical motion, sound)
and their characteristics.
Essential Question:
• How are the different forms of
energy related?
Mechanical Energy
• The form of energy
associated with the
position and
motion of an
object
Mechanical Energy = Potential energy + Kinetic Energy
Thermal Energy
• The total
potential and
kinetic energy
of the
particles
(atoms and
molecules) in
an object.
Also called HEAT Energy!!!
Electrical Energy
• The energy of
electric charges –
can be a form of
kinetic or
potential
depending on
whether the
charges are
moving or stored.
Chemical Energy
• Is potential
energy stored in
the chemical
bonds that hold
chemical
compounds
together (food,
matches, cells).
Nuclear Energy
• Potential energy that is stored in
the nucleus of an atom; released
during a nuclear reaction (fission,
fusion)
Electromagnetic Energy
• Energy that travels in
waves, having some
electrical and some
magnetic properties.
Also called
Sound and
Light/Radiant
Energy!!!
Remember MR. CHEN
• M-MECHANICAL ENERGY
• R – RADIANT
(ELECTROMAGNETIC/LIGHT&SOUND)
• C-CHEMICAL ENERGY
• H-HEAT ENERGY (THERMAL)
• E-ELECTRICAL ENERGY
• N-NUCLEAR ENERGY
Essential Question:
• How are different forms of
energy related?
Standard: S8P2a
• Explain energy transformation in terms
of the Law of Conservation of Energy.
•OPEN YOUR
TEXTBOOK TO
P.454!!!!!!
Energy Transformation
• A change from one form of energy
Multiple Transformations – A series
to another
Single Transformations – One
form of energy needs to be
transformed into another to get
work done. Ex: Toaster
transforms electrical energy to
thermal energy to toast your
bread.
of energy transformations is needed
to do work. Ex: Mechanical energy
used to strike a match is transformed
to thermal energy, releasing stored
chemical energy, which is
transformed to thermal energy and
electromagnetic energy.
Transformations Between Potential
and Kinetic Energy
• Demonstration
Law of Conservation of Energy
• When one form of energy is transformed to
another, no energy is destroyed in the
process. Energy cannot be created or
destroyed.
Friction transforms
mechanical energy to
thermal energy!
Roller Coaster Activity Instructions
• Watch this video first!
• Now read the instructions on the worksheet
that your teacher gives you.
Einstein’s Theory of Relativity
• Einstein theorized that matter can be
transformed to energy because
destroying just a small amount of
matter releases a huge amount of
energy. He MAY be wrong according
to recent research...!!!
• In some situations, energy alone is
not conserved; however, since
matter can be transformed to energy,
scientists say matter and energy
together are always conserved.