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Chapter 13
Energy
13.1 What is Energy
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
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
Energy
Kinetic energy
Potential energy
Gravitational potential energy
Elastic potential energy
Mechanical energy
Thermal energy
Electrical energy
Chapter 13
Chapter 13 Vocabulary
Chemical energy
Nuclear Energy
Electromagnetic energy
Energy transformation
Law of conservation of energy
Matter
Fossil fuels
Combustion
Chapter 13