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Energy:
Forms and
Changes
Forms of Energy

The main forms of energy
are:
Thermal(Heat)
 Chemical
 Electromagnetic(light)
 Nuclear
 Mechanical(motion)
 Electrical
 Sound

Energy Transformations or
Conversions
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Most forms of energy can be transformed
into other forms.
A change from one form of energy to
another is called an energy
transformation.
Transformations Between
Potential and Kinetic Energy
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One of the most common energy transformations is the
transformation between potential energy and kinetic
energy.
In waterfalls such as Niagara Falls,
potential energy is transformed to kinetic
energy.
The water at the top of the falls has
gravitational potential energy.
As the water plunges, its velocity
increases.
Its potential energy becomes kinetic
energy.
Kinetic-Potential Energy Conversion
Roller coasters work because of the energy that is
built into the system. Initially, the cars are pulled
mechanically up the tallest hill, giving them a great
deal of potential energy. From that point, the
conversion between potential and kinetic
energy powers the cars throughout the
entire ride.
Kinetic vs. Potential Energy
At the point of maximum potential energy, the car has
minimum kinetic energy.
Common Energy Transformations Every day,
energy transformations are all around you. Some
of these transformations happen inside you!
Energy and Friction
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So what happens to the energy of
the
top?
As the top spins, it encounters friction with the floor and
friction from the air.
Whenever a moving object experiences friction,
some of its kinetic energy is transformed into
thermal energy. (Why you cannot have
perpetual motion machines)
So, the mechanical energy of the spinning top is
transformed to thermal energy.
The top slows and eventually falls on its side, but its
energy is not destroyed—it is transformed.
Conservation of Energy
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If you set a spinning top in motion, will
the top remain in motion forever?
No, it will not.
Then what happens to its energy?
Is the energy destroyed?
Again, the answer is no.
The law of conservation of energy
states: Energy is not created nor
destroyed only changed into other
forms. The total amount of energy
remains the same.
What happens when electrical energy is
changed to thermal energy?
a.
An energy transfer takes place.
b. A force change takes place.
c.
An energy conversion takes place.
d. An electrical conversion takes place.

What happens when electrical energy is
changed to thermal energy?
a.
An energy transfer takes place.
b. A force change takes place.
c.
An energy conversion takes place.
d. An electrical conversion takes place.

Any time an energy conversion
takes place, some of the original
energy is converted to which one
of the following?
a. sound energy
b. potential energy
c. light energy
d. thermal energy
Any time an energy conversion
takes place, some of the original
energy is converted to which one
of the following?
a. sound energy
b. potential energy
c. light energy
d. thermal energy
When you eat fruits and
vegetables, which of the
following types of energy are
you taking in?
a.
b.
thermal energy
sound energy
c.
d.
electrical energy
chemical energy
When you eat fruits and
vegetables, which of the
following types of energy are
you taking in?
a.
b.
thermal energy
sound energy
c.
d.
electrical energy
chemical energy
Which of the following is a conversion from
light energy to chemical energy?
a.
turning on a stove to heat dinner
b. turning on a lamp
c.
growing an apple tree
d. making toast in a toaster
Which of the following is a conversion from
light energy to chemical energy?
a.
turning on a stove to heat dinner
b. turning on a lamp
c.
growing an apple tree
d. making toast in a toaster