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Unit 3 Lesson 2 Conservation of Energy
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Unit 3 Lesson 2 Conservation of Energy
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What are some forms of energy?
1. Mechanical energy is the sum of an object’s
kinetic energy and potential energy.
• Kinetic – energy of motion
• Potential – energy of position
2. Sound energy results from the vibration of
particles. This is why sound cannot travel through
empty space.
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Unit 3 Lesson 2 Conservation of Energy
What are some forms of energy?
3. Electromagnetic energy is transmitted in the
form of electromagnetic waves (EM waves).
• EM waves are produced by the vibration of
electrically charged particles.
• Electromagnetic waves can travel through
empty space.
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Unit 3 Lesson 2 Conservation of Energy
What are some forms of energy?
4. Chemical energy is the energy stored in chemical
bonds that hold chemical compounds together.
5. Thermal energy is the energy an object has due
to the motion of its molecules.
• The faster the molecules move, the more
thermal energy the object has.
• Heat is the transfer of thermal energy.
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Unit 3 Lesson 2 Conservation of Energy
What are some forms of energy?
6. Nuclear energy comes from the nucleus of an
atom.
• When an atom’s nucleus breaks apart, or when
the nuclei of two atoms join together, energy is
released.
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Unit 3 Lesson 2 Conservation of Energy
Transformers
What is an energy transformation?
• An energy transformation takes place when
energy changes from one form into another form.
• Any form of energy can change into any other
form of energy.
• Often one form of energy can change into two or
more other forms.
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Unit 3 Lesson 2 Conservation of Energy
What is an energy transformation?
• In a flashlight, chemical energy is transformed
into electrical energy.
• The electrical energy is then transformed into light
and thermal energy.
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Unit 3 Lesson 2 Conservation of Energy
How does mechanical energy
transform?
• Although mechanical energy can be transformed
into another form of energy, transformations
between kinetic and potential energy can also
take place.
• However, regardless of the changes in kinetic and
potential energy, the total amount of mechanical
energy remains the same.
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Unit 3 Lesson 2 Conservation of Energy
Energy In = Energy Out
What is conservation of energy?
• The law of conservation of energy states that
energy cannot be created or destroyed; it can
only change forms.
• A group of objects that transfers energy only to
one another is called a closed system.
• In a closed system, all the energy is conserved.
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Unit 3 Lesson 2 Conservation of Energy
How is energy conserved?
• Energy is measured in Joules.
• The law of conservation of energy means that the
total number of joules of energy in a closed
system always remains the same.
• When analyzing how energy is conserved in a
closed system, it is important to always consider
all objects in the system.
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Unit 3 Lesson 2 Conservation of Energy
Efficiency Expert!
How is efficiency measured?
• When energy is transformed from one form to
another form, not all of it is turned into useful
energy.
• Usually, some energy is also transformed into
thermal energy.
• Efficiency is the ratio of useful output energy to
input energy.
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Unit 3 Lesson 2 Conservation of Energy
How is efficiency measured?
• Energy efficiency is highly desirable because it
means as much energy as possible is converted to
useful forms.
• Efficiency is calculated by dividing energy out by
energy in and then multiplying by 100 percent.
• If less energy is wasted, then less energy is
needed to operate a machine.
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