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Energy
Chapter 13
13.1 What is Energy?
 When an object or living thing does work on another object,
some of its energy is transferred to that object
 Energy is measured in joules
 Power is involved whenever energy is being transferred
Power = Energy Transferred
Time
 Kinetic Energy
-depends on both mass & velocity
-changing the velocity of an object will have a greater
effect on its kinetic energy than changing its mass.
Kinetic Energy = ½ x Mass x Velocity²
- What Is Energy?
Kinetic Energy
 Kinetic energy increases as mass and
velocity increases.
 Gravitational Potential Energy
 GPE is equal to the work done to lift the object
 The force you use to lift an object is equal to its
weight
 The distance you move an object is its height
 GPE increases as weight & height increase
 Gravitational Potential Energy = Weight x Height
13.2 Forms of Energy
 Mechanical Energy
 A combination of potential energy & kinetic energy
 Sometimes an object’s mechanical energy is its kinetic
or potential energy only.
Mechanical Energy = Potential Energy + Kinetic Energy
 Thermal Energy
 All objects are made of particles called atoms &
molecules that are constantly in motion
 The faster these particles move the more kinetic
energy they have
- Forms of Energy
Calculating Mechanical
Energy
The kinetic energy of
a 500-N diver during a
dive from a 10-m
platform was
measured. These data
are shown in the
graph.
Calculating Mechanical
Energy
 According to the
graph, how much
kinetic energy does
the diver have at 8 m?
About 1000 J
Calculating Mechanical
Energy
 Using the graph, find
the kinetic energy of
the diver at 6 m. Then
calculate the diver’s
potential energy at
that point.
Kinetic energy = about
2000 J; potential energy
= about 3000 J
- Forms of Energy
Calculating Mechanical
Energy
 The mechanical
energy of the diver is
the same at every
height. What is the
mechanical energy of
the diver?
About 5000 J
 Electrical Energy
 Depending on whether the charges are moving or
stored, electrical energy can be a form of kinetic or
potential energy
 Chemical Energy
 Almost everything is made of chemical compounds
 Bonds between atoms and molecules hold chemical
compounds together
 Nuclear Energy
 Released during a nuclear reaction
 Electromagnetic Energy
 Travels in waves that have some electrical properties
and magnetic properties
13.3 Energy Transformations &
Conservation
 Most forms of energy can be transferred into other
forms of energy
 One of the most common energy transformations is
between potential and kinetic energy
 Conservation of Energy
 If you add up all the new forms of energy after a
transformation, all of the original energy will be
accounted for
 Matter can be transformed to energy
 A small amount of matter releases a huge amount
of energy
- Energy Transformations and Conservation
 Most forms of energy can be transformed
into other forms.
- Energy Transformations
and Conservation
 A pendulum
continuously
transforms
energy from kinetic to potential energy and
back.
13.4 Energy & Fossil Fuels
 A fuel is a material that contains stored potential
energy
 Fossil Fuels contain energy that came from the sun
Graphic Organizer
Energy
exists as
Potential
energy
Kinetic
energy
measured in
is the
ability to
do
Joules
Work
can be
Elastic
Gravitational
which at a
given rate is
Power