Download The Law of Conservation of Energy

Nature of Energy
 Energy is all around you!
 You can hear energy as sound.
 You can see energy as light.
 And you can feel it as wind.
Energy is usually described
as kinetic or potential
Thermal or Heat Energy
 The internal motion of the
atoms is called heat energy,
because moving particles
produce heat.
 Heat energy can be produced
by friction.
 Heat energy causes changes
in temperature and phase of
any form of matter.
Chemical Energy
 Chemical Energy is required to bond
atoms together.
 And when bonds are broken, energy is
released.
 Fuel and food are forms
of stored chemical energy
Electromagnetic Energy
 Light is a form of electromagnetic energy.
 Each color of light (Roy G Biv) represents a
different amount of electromagnetic energy.
 Electromagnetic Energy is also carried by X-rays,
radio waves, and laser light.
Electromagnetic Spectrum
Increasing Energy
Electromagnetic
Energy
 Power lines carry
electromagnetic energy into your
home in the form of electricity.
Nuclear Energy
 The nucleus of an atom is the source of
nuclear energy.
 When the nucleus splits (fission), nuclear
energy is released in the form of heat energy
and light energy.
 Nuclear energy is also released when nuclei
collide at high speeds and join (fuse).
Nuclear Power Plant
Nuclear Energy
The sun’s
energy is
produced from a
nuclear fusion
reaction in which
hydrogen nuclei
fuse to form
helium nuclei.
Mechanical Energy
 Mechanical energy is due to
the position and motion of
the object.
 When work is done to an
object, it acquires energy.
The energy it acquires is
known as mechanical
energy.
Mechanical Energy
 What happens to the mechanical
energy of an apple as it falls from a
tree?
Mechanical Energy
 As the apple falls to the ground, its height
decreases.
 Therefore, its GPE decreases. Potential
energy that is dependent on height is
called gravitational potential energy.
 The potential energy is not lost… it is
converted into kinetic energy as the
velocity of the apple increases.
 What happens to the mechanical
energy?
Mechanical Energy
 The mechanical energy does not change
because the loss in potential energy is
simply transferred into kinetic energy.
 The energy in the system remains
constant!!
Swinging Along
 Think about the changes in energy when
you are on a swing…
 At what point do you have the most
potential energy?
 At what point do you have the most
kinetic energy?
 What happens to the mechanical
energy?
Conservation of Energy
 Energy is transformed… not destroyed!!
The Law of Conservation of Energy
• The law of conservation of energy
states that energy cannot be
created or destroyed.
• Energy can be changed from one
form to another. Changes in the
form of energy are called
energy conversions.
Energy Conversion
Examples
The Law of Conservation of Energy
• Even when energy changes form from
electrical to thermal and other energy forms
as in the hair
dryer shown
energy is never
destroyed.
The Law of Conservation
of Energy
 The Law of Conservation of Energy
states that energy cannot be created or
destroyed.
 The big picture… the total energy in the
universe remains constant.
Changing Forms of Energy
 Energy is most noticeable as it
transforms from one type to another.
 What are some examples of transforming
electrical energy?
 A lightbulb
 A hair dryer
Potential to Kinetic
 The most common energy
conversion is between potential
and kinetic energy.
 All forms of energy can be in either
of two states:
 Kinetic is the energy of motion.
 Potential is stored energy
Changing forms of Energy
 An example of transforming chemical
energy is a car engine.
 Chemical potential energy in gasoline is
transformed into kinetic energy of the car
as it moves!!