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Chapter 13
Energy
13.1 What is Energy
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Energy - The ability to do work or cause
change (such as moving an object some
distance)
 Work is the transfer of energy.
 Energy is measured in Joules
 Power is the rate at which energy is
transferred (converted from one form to
another) or the amount of energy transferred
in a unit of time.
Chapter 13
13.1 What is Energy

Power = Energy transferred / Time
 Review
Power - The rate at which work is done
power = work/time
power = force x
distance/time
power units = J/sec = Watts (W)
Chapter 13
13.1 What is Energy
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Two basic kinds of energy: kinetic energy and
potential energy
 Kinetic energy (KE) - energy of motion
(kinetos)
 KE = 1/2 mass x velocity2
Potential energy (PE) - stored energy due to
position or shape of an object (gravitational or
spring)
 Gravitational Potential Energy = work done to
lift the object
Chapter 13
13.1 What is Energy

Remember: Work = Force X Distance
 Gravitational potential energy =
Weight X Height
 (Weight is a Force = Mass X Acceleration)
 Therefore PEG = mass x acceleration due to
gravity (9.8 m/sec2) x height
 Elastic potential energy – Energy associated
with objects that are stretched or compressed
Chapter 13
13.2 Forms of Energy
Energy – The form of
energy associated with the position and
motion of an object
 Mechanical Energy = Potential energy +
Kinetic energy
 Mechanical
Chapter 13
13.2 Forms of Energy
 Forms
of energy associated with the
particles of objects include thermal
energy, electrical energy, chemical
energy, nuclear energy, and
electromagnetic energy.
Chapter 13
13.2 Forms of Energy
energy – heat – The total
potential and kinetic energy of the
particles in an object
 Electrical energy – electricity – The
energy of electric charges
 Thermal
Chapter 13
13.2 Forms of Energy
 Chemical
energy - chemical
reaction/bonds – The potential energy
stored in the chemical bonds that hold
compounds together
 Nuclear energy – fission & fusion – The
potential energy stored in the nucleus of
an atom
Chapter 13
13.2 Forms of Energy
 Electromagnetic
energy - light, radiation
– Travels in waves which have some
electrical and magnetic properties
Chapter 13
13.3 Energy Transformations
and Conservation

Most forms of energy can be transformed into
other forms.
 energy transformation- the process of
changing one form of energy into another
 One of the most common energy
transformations is the transformation between
potential energy and kinetic energy.
Chapter 13

body - convert chemical energy in food to
mechanical energy to move muscles
match - mechanical  thermal  chemical 
thermal  light
Book examples - waterfall, juggling, pole vault,
pendulum
The law of conservation of energy – According to the
law of conservation of energy, energy cannot be
created or destroyed. The total amount of energy is
the same before and after any transformation.
Chapter 13
friction  converts
mechanical to thermal energy,
reduces efficiency
Chapter 13
Energy and Matter  Einstein’s
theory of relativity
 Matter can be transformed to energy.
 Matter is anything that has mass and
takes up space.
 Therefore, matter and energy together
are always conserved.
Chapter 13
13.4 Energy conversions and
fossil fuels

Formed from the remains of ancient plants
and animals that lived 400 million years ago.
 Coal, petroleum, natural gas - chemical
potential energy
 Fossil fuels - contain energy that came from
the sun.
 Energy conversions pg. 464 – Flowchart
Chapter 13
13.4 Energy conversions and
fossil fuels
 Fossil
fuels can be burned to release
the (potential) chemical energy stored
millions of years ago.
 Combustion – The process of burning
fuels
 Non-Renewable Energy
Chapter 13
Chapter 13 Vocabulary
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Energy
Kinetic energy
Potential energy
Gravitational potential energy
Elastic potential energy
Mechanical energy
Thermal energy
Electrical energy
Chapter 13
Chapter 13 Vocabulary
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Chemical energy
Nuclear Energy
Electromagnetic energy
Energy transformation
Law of conservation of energy
Matter
Fossil fuels
Combustion
Chapter 13