7
Chapter 27
Energy: The Foundation of Technology
563
We use the word
energy
in different
ways. For instance, we might say, “I don’t
have the energy to mow the lawn.” We
might worry about our energy dependence
on foreign petroleum, and we might hear
people talking about energy conserva-
tion. Not everyone using the word knows
exactly what it means, however.
The word
energy
comes from the Greek
word
energeia
, which means “work.” As
time passed, the word came to describe the
force that makes things move. Today,
energy
is defined as “the ability to do work.” This
ability includes a broad spectrum of acts.
Energy is used in simple human tasks, such
as walking, running, and exercising. The
ability to do work can be obtained from
petroleum and then used to power a ship
across the ocean. See
Figure 27-1.
Energy
can be used to provide motion in vehicles
and machines and produce heat and light.
The ability to do work is fundamental to
our communication technologies, and it is
used in manufacturing products and con-
structing structures. Energy is everywhere
and is used by all of us.
In this chapter, we look at energy from
a variety of angles. We discuss the types
of energy; the connection among energy,
work, and power; and the forms of energy
and their interrelationships. Also, we
examine the various sources of energy and
whether energy technology is helpful or
harmful.
Types of Energy
Two types of energy exist. Energy can
be associated either with a force doing the
work
or with a force that has the capabil-
ity of doing work.
Kinetic energy
is energy
involved in moving something. This energy
is the energy in motion. A hammer striking
a nail is an example of a technological act
using kinetic energy. A sail capturing the
wind to power a boat uses kinetic energy.
Likewise, a river carrying a boat or turn-
ing a waterwheel is an example of kinetic
energy.
Not all energy is being used at any given
time. Some energy is stored for later use.
Energy in this condition has the capability,
Figure 27-1.
Energy is used in all actions, from walking to powering complex
technological devices.
Human Activities
Technological Systems
Energy Is Used for . . .
New Terms appear in bold italics where they
are defined.
450
Section 6
Applying Technology: Communicating Information and Ideas carrier signal. This type of broadcast radio
is assigned the frequencies between 540
and 1600 kHz.
Later, radio broadcast systems using
frequency modulation (FM)
were devel-
oped. These systems encode
on the carrier wave by changing wave’s
frequency. The 200 separate FM
broadcast frequencies range 88.1
107.9 MHz. Look back to Chapter an
explanation of the operation radio
munication systems. Included dis-
cussion is an explanation the
of radio transmitters and
receivers.operationthatcom-fortoradio-7inthemessagefromoftheof
Television Broadcast
Systems
Television broadcast systems areis
really two systems in one. Each channel
assigned a bandwidth. See
Figure 22-12.
A
Academic Connections: Communication
Advertising
Many commercial telecommunication broadcasts are supported
through advertising. An important part of this advertising is a slogan.
These slogans are designed to keep the product or company in
mind. We probably have all listened to the radio and, hours later,
recalled an advertising jingle. For exampl
e, many of us remember such slogans
as “When you care enough to send the very best” (Hallmark cards) and “We
harder” (Avis rental cars).
The purpose of an advertising slogan (sometimes called a
tag
or
tag
linetryisaretoInn
)
to leave the brand message in the mind of a potential customer. Many slogans
also protected as trademarks. They are registered with the trademark
office. This registration allows the company to use the registered symbol (®).
A good slogan must meet several criteria. First, it have the ability be
recalled. Such a slogan is called a
memorable
sloganmustgovernment
. Second, a good slogan
should present a key benefit of the product or service. For example, Holiday
has used the slogan “Pleasing people the world over.” Third, the slogan should
differentiate the product or service. The Hallmark slogan above suggests that
Hallmark cards are better than any others.
An effective slogan should generate positive feelings about the product
or
service. Such a slogan should cause customers to purchase the item and feel
good about owning it. Can you think of three examples of effective slogans?
Figure 22-11.
Radio waves are changed
to carry the message through AM or FM.
Notice how the amplitudes of the sound
wave and the carrier wave have been
blended in AM. The amplitude of the
combined waveform oscillates in a pattern
similar to the sound wave. Notice, in the
frequency modulated waveform, how
frequency varies in a pattern with
thethe
initial sound wave.
Audible Sound
AM
Carrier Wave FM
501
Chapter 24
Using Technology to Transport
STEM Connections: Science
Newton’s First Law of Motion
Many scientific principles come into play when we
use the various kinds of transportation systems now avail-
able. Among those principles are Newton’s laws of motion.
For example, we can use Newton’s first law of motion
to explain why we need seat belts in our automobiles.
Newton’s first law of motion states that a moving object
continues moving at the same speed, in the same direc-
tion, unless some force acts on it. This tendency of an
object to resist change is also called
inertia.
Thus, when we are traveling in an automobile at, say,
50 miles per hour, we continue moving at this speed, even
when we forcefully apply the brakes of the car. We have
applied force (the brakes) to stop the car. Such force works
only on the car, however, not on us. Therefore, we need
the seat belt because it provides the force needed to stop us from to
move and perhaps hitting the windshield. Newton’s first law of motion also involves
the concept of friction. Using another method of transportation an example, can
you think of a way friction affects this object when it is
moving?ascontinuing
People
Cargo
Inertia keeps this gyroscope
spinning.
þ
iStockphoto.com/JohnnyLye
Figure 24-7.
Vehicles such as these aircraft are designed differently for cargo and people.
Alaska Airlines, United Airlines
STEM Connections provide information on
a topic relevant to the chapter material that
connects the content to math or science.
Academic Connections provide information
on a topic relevant to the chapter material
that connects the content to communication
and history.