Download toe student workbook outline

WHAT IS ENERGY AND HOW DO FORCES TRANSFER
ENERGY?
ENERGY, what do you think of when you hear the word energy? Do you
picture a speeding racecar or perhaps a spinning windmill? Maybe you imagine
a street luge participant speeding down a twisting mountain road or you think of
an explosion.
We frequently read about energy in the
newspaper. In the news, ENERGY usually
refers to electrical energy or the energy stored in
oil/gasoline. These are two good examples of
energy that dramatically affect our daily lives.
Are there other examples? How do we make
use of this energy? Why are these two forms so
important to us?
Energy is a topic that makes its way into
all of the sciences. As you move through this
year’s science class you will learn about energy in many different forms and in
many different contexts. Energy is hard to define, so we generally define it by
providing examples of energy. Energy can move from one place to another and
it can also change forms. Keeping track of the energy in an example can help
you understand and explain the science involved.

Why is energy so
important to us?

What types of
energy do you
encounter most
often?

How does energy
get from one
place to another?
1
© 2009 Delaware Science Coalition / Delaware Department of Education
Section I: Reviewing Key Energy Concepts
MAKING SENSE OF ENERGY …
Energy is the most central concept in all of science. Energy is the thread
that ties the physical, life, and earth sciences together. Matter and energy make
up the universe. While matter is tangible and something that we can hold in our
hands, energy is far more abstract.
We commonly say that objects have energy, but we can’t really see this
energy. We recognize energy mainly through the effects it has on objects. We
see the changes that occur when an object or substance has energy and shares
that energy with other objects.
Energy is not easily defined. So scientists study energy by looking at the
effects energy has on other things. A definition
that is often used for energy is “the ability to
bring about some sort of change.” If something
has energy, then that energy can cause a
change in the object or in its surroundings. By designing experiments to
study these changes, scientists learn more about energy.
Energy comes in many forms. You may remember some of these forms
from your 8th grade study of energy or from previous studies in energy. It is
important for us to be able to identify the forms of energy. It is also important to
be able to describe how energy moves from one place to another and changes
forms.
In some cases, the same type of energy is simply passed along from one
object to another; this is called an energy transfer. In other cases, the energy
changes forms (converted from one form of energy to another form of energy);
this process is called energy transformation. It is common for many energy
transfers and transformations to happen together. It is often helpful, in order to
understand a sequence of events, to create a description of how the energy
2
© 2009 Delaware Science Coalition / Delaware Department of Education
moved. This is generally done using words and pictures; the result is called an
energy chain.
A REVIEW OF SOME COMMON FORMS OF ENERGY ….
Mechanical Energy (ME) – the combination of potential and
kinetic energies. Mechanical energy is a broad category of energy that
includes the two main forms of energy, potential and kinetic. In many cases
the combination of the two forms is an important quantity to keep track of, so
the term mechanical energy refers to the sum of these two forms.
Kinetic Energy (KE) – the energy of motion. The energy
associated with moving objects is called kinetic
energy (KE), and is often referred to as the most
fundamental form of energy. The size of the KE is
determined by an object’s speed and its mass. A
moving baseball has kinetic energy. If you have
ever been hit by a pitched ball, you are aware of
the energy a moving object can have.
Gravitational Potential Energy (GPE) – the energy of position.
This is energy that an object possesses due to its
position. The size of the GPE is determined by the
object’s mass and its height above the ground. As
a person climbs a ladder, increasing his/her height
above the ground, he/she increases his/her GPE.
Heat Energy (HE) – the
random kinetic energy
of particles. Heat energy
3
© 2009 Delaware Science Coalition / Delaware Department of Education
is the random, and very disorganized, kinetic energy of the particles in a
substance. Thermal energy is another term often used as a synonym for heat
energy. In most cases the distinction between the exact definitions of heat
energy and thermal energy is not made.
Due to the random nature of this form of energy, it is difficult to make heat
energy a useful form of energy. For this reason it is usually the form of energy
that appears at the end of energy chains. It happens so often that scientists refer
to heat energy as the “graveyard of
energy”. For
example, if you pound a nail into a piece of
wood, the nail
gets hot due to the energy transferred to it
by the hammer
and the force of friction with the wood.
Chemical Potential Energy (CPE) – the energy of bonds. Chemical
potential energy, sometimes just called chemical
energy, is the energy stored in the bonds that hold
the particles in a substance together. When these
bonds are formed, or are broken, energy transfers
and/or transformations take place. In many cases,
the energy stored in the bonds of substances is
transformed into other forms of energy. Food is a
source of chemical energy for our bodies, so we
sometimes use ‘food energy’ in place of chemical energy in energy chains that
involve people. In most cases this chemical potential energy is later transformed
into heat energy
4
© 2009 Delaware Science Coalition / Delaware Department of Education
Electromagnetic Energy – the energy of waves. This form of energy
is often referred to as solar energy or light energy. Electromagnetic energy is
the energy that is carried by electromagnetic waves. The most common form of
electromagnetic energy is “light”. Light energy is
a term that can be used to describe the energy
ranges that our human eyes are sensitive to and
it may include some forms of ‘light’ that we can
not see with our eyes, such as infrared and
ultraviolet. The sun is the most important source
of electromagnetic energy for the Earth,
supplying the vast majority of our planet’s
energy. In some cases, chemical potential
energy can be transformed into electromagnetic
energy. This form of energy is very important in the scientific field of astronomy.
Electrical energy is a subset of electromagnetic energy, characterized by
moving charges. It is used to run appliances and make artificial light. When the
charged particles vibrate, they transfer energy by electromagnetic waves.
5
© 2009 Delaware Science Coalition / Delaware Department of Education
Sound Energy – the energy of vibrating particles. This form of
energy is transferred by mechanical waves. The particles that make up a
substance vibrate in a highly organized manner and transfer energy through the
substance. The particles in the substance vibrate, but do not change their
location. In most cases, sound energy is classified into three categories;
infrasonic is the sound that is below
our human hearing level, sonic is the
sound that our human ears are
sensitive to, and ultrasonic is the
sound that is above our human
hearing level. Have you ever made a
tin can telephone? If so, you have
already experimented with sound
waves and how vibrations are involved
in the energy transfer process.
A good example of the use of sound waves is sonar. Humans have
created devices that enable us to send out a sound wave and listen for the echo
so that we can determine how far away something is to the source. Seismic
waves or “earthquake” waves also fit into this category because they involve the
transfer of energy through vibrating matter in the form of mechanical waves.
Ultrasounds in the medical field are used for a variety of purposes. Perhaps you
have seen an ultrasound image of a baby. In most energy chains, the sound
energy is transformed into heat energy (the disorganized and random KE of
particles
Elastic Potential Energy (EPE) – energy of deformed materials.
6
© 2009 Delaware Science Coalition / Delaware Department of Education
This form of energy comes from the stretching or compressing of elastic
materials. When an elastic material is deformed (by stretching or compressing),
it exerts a force, called the elastic force, to return to its original shape. In many
cases, the elastic material is held temporarily in this deformed position and the
material has a stored amount of energy.
Bow hunters make use of EPE to shoot their arrows. The EPE of the bow
string is converted to the KE of the arrow. Catapults and slingshots also operate
in this manner. Tennis players rely on the elastic properties of their tennis
racquets and the tennis ball. Pole
vaulters depend on the stored
energy in the bent pole to help
them get over the bar. The science
behind the design of the pole relies
on knowledge of how material store
EPE. Surprisingly, certain types of
rock can have elastic properties.
They can be stretched or
compressed under huge forces.
TWO IMPORTANT PROPERTIES OF
ENERGY ARE:

Energy transfer is the passing of energy from one object to another.
7
© 2009 Delaware Science Coalition / Delaware Department of Education

Energy transformation is the changing of energy from one form of
energy to another form of energy.
MAKING SENSE OF ENERGY … the Law of Conservation of Energy
8
© 2009 Delaware Science Coalition / Delaware Department of Education
GOALS





Review the concepts of energy transfer and energy transformation and the
basic forms of energy
Discuss the significance of the Law of Conservation of Energy.
Describe how force and distance combine mathematically to quantify the
energy transfer in a process called work.
Quantify the work done (energy transferred or transformed) in examples.
Create and explain energy chains.
CONNECTIONS
Scientific Content –
Energy can exist in different forms.
 Energy can be categorized into several forms (kinetic, potential,
elastic, heat, electrical, etc.) Since energy can not be seen, it is
defined by the change that is produced when energy is transferred
and/or transformed.
 Mechanical energy is the sum of both the kinetic energy (KE) and
the Gravitational Potential Energy (GPE) of an object. KE is
dependent upon the mass and speed of the object; GPE is
dependent upon the mass and the height of the object.
 Chemical potential energy (or chemical energy) is the potential
energy stored in the bonding of the particles that make up matter.
 Heat energy is the random kinetic energy of the particles that make
up a substance.
 Electromagnetic energy is the energy transferred by
electromagnetic waves
 Elastic potential energy is the energy stored in elastic materials
by compressing or stretching them beyond their normal position.
 Sound energy is the energy carried by the organized vibrations of
particles as a mechanical wave.
Energy can be transferred from one object to another.
 An energy transfer occurs when energy is passed from one object
to another object but stays in the same form.
 When one object pushes or pulls on another object often (but not
always) energy is transferred from one of the objects to the other.
As a result of this transfer, the motion of one or both of the objects
will change.
 When a force transfers energy, the process is called work. The
“work done” by the force involved in the energy transfer can be
9
© 2009 Delaware Science Coalition / Delaware Department of Education

quantified by multiplying the force by the distance over which that
force acted during the energy transfer process.
When kinetic energy is transferred to a large stationary solid this
energy is transferred to the particles that make up the object. The
kinetic energy may take the form of organized vibrations within the
solid (a mechanical wave), but will ultimately become the random
vibrational kinetic energy of the particles. This collective random
kinetic energy of the particles is called heat energy.
Energy can be changed from one form to another. This process is
called the transformation of energy.
 An energy transformation occurs when energy is passed from one
object to another and it changes forms.
 In most cases, the energy of objects eventually becomes the
random kinetic energy of the particles that make up the object. We
call this form of energy heat energy.
By understanding energy transformation and energy transfer, we can
begin to understand that the energy of an object can change forms
and be passed to other objects but cannot be created nor destroyed.



Energy can not be created nor destroyed. Energy can be
transferred from one object to another and can be transformed from
one form to another, but the total amount of energy never changes.
This concept is known as the Law of Conservation of Energy and is
one of the most significant laws in science.
Identifying the energy transformations and transfers that occur
when an event takes place helps us to better understand what
factors influence these changes. This understanding helps us to
appreciate how objects interact and enable us to make predictions
about the outcomes of these changes.
Energy chains help to understand the Law of Conservation of
Energy. Identifying where energy comes from and where it goes
builds an acceptance that energy can change form, or be
transferred from object to object, but cannot disappear. When
energy seems to go away, it really is just changing forms and
spreading out. These concepts are the foundation for the Law of
Conservation of Energy.
Scientific Process  Identifying the different forms of energy, and where it is transferred
and/or transformed during an event are important skills that lead to
a richer understanding of the flow of energy in everyday
phenomena.
10
© 2009 Delaware Science Coalition / Delaware Department of Education

Creating energy chains requires an understanding of the flow of
energy that takes place during the changes in any physical system.
Accurate completion of an energy chain and/or diagram reflects a
student’s understanding of the flow of energy in systems.
Math/Graphing  Calculations of work will be completed. Graphical displays of
energy flow will be created and analyzed.
11
© 2009 Delaware Science Coalition / Delaware Department of Education