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Applied Technology
Level 5
Worldwide Interactive Network, Inc.
1000 Waterford Place, Kingston, TN 37763 • 888.717.9461
©2008 Worldwide Interactive Network, Inc. All rights reserved.
Copyright © 1998 by Worldwide Interactive Network, Inc. ALL RIGHTS RESERVED.
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2 • Applied Technology
INTRODUCTION
Hi, I’m Edwin.
Hi! Let me introduce myself to you. I am EdWIN,
and I will be your friendly guide through this study.
Now, you may have met me before in a different course
or in an earlier level. If you have, I hope that you have
found that I am not too tough of a taskmaster. Look
for me to pop up every now and then with a tip, hint,
or maybe even a quiz question or two!
You are about to begin Level 5 of Applied Technology.
If you have already completed Level 4, you know that
it wasn’t too tough. Even if you are a “technophobe,”
you probably found that it wasn’t as difficult as you
thought it might be.
We will be studying thermodynamics, fluid
dynamics, electricity, and mechanics in this course. This
level will cover the basics once again for your review.
The main difference will be that the exercises will be
more difficult. The great thing about this type of
learning is that you generally can set your own pace.
Consequently, you will not have to move on until you
feel you have learned the material to your satisfaction.
So, if you are ready, so am I. Turn the page and let’s
begin!
Applied Technology • 3
STRATEGIES
Problem-Solving Strategies
The basic components of effective problem-solving strategies are –
• Identifying the problem (“What is the goal?” and “What limits does the goal
impose?”)
• Analyzing and interpreting data (reading a gauge, interpreting a printout)
This includes identifying and disregarding nonessential data.
• Exploring and evaluating solutions (“What options are available?” and “Which
option is best, taking into account many variables, including cost, time, human
resources, materials, environment, and expertise?”)
One well-known problem-solving model is the IDEAL* model. The IDEAL model
was designed as an aid for teaching and improving problem-solving skills. The
IDEAL process includes the following steps:
I
D
E
A
=
=
=
=
L
=
Identify the problem (determine what needs to be done).
Define and represent the problem (sharpen and clarify the boundaries).
Explore alternative approaches (analyze and evaluate alternatives).
Act on a plan (determine the logical steps to be used and how to progress
through the steps).
Look at the result (determine whether or not the plan worked).
The exercises in this workbook guide learners through the IDEAL problem-solving
process.
* The IDEAL Problem Solver: A Guide for Improving Thinking, Learning, and Creativity , © 1984.
Permission for use granted by W.H. Freeman and Company/Worth Publishers, all rights reserved.
4 • Applied Technology
STRATEGIES
Problem-solving strategies are critical to any instruction aimed at improving all
levels of applied technology skills. To be an effective technological problem solver,
you need to be able to do the following:
•
•
•
•
•
•
Understand cause-effect relationships (What parts of systems affect and are
affected by other parts?)
Make comparisons (What commonalities and differences do systems have?)
Recognize probable outcomes (How will the system react to a specific action?)
Predict what should happen next (Based on what has been observed, what is
known about a specific system, and what is known about related scientific
principles, make a prediction about what will happen next.)
Judge spatial relationships (Visualize how a system operates and mentally rotate
system parts to solve problems within a given system.)
Notice what appears out of place (Observe a malfunctioning system in operation
to determine what is not working correctly.)
Course Strategies
The best way for me to help you be an effective problem solver is to give you
opportunities to develop and refine your problem-solving skills. Therefore, I will
use the following strategies:
• I will minimize instructions so that you are encouraged to invent innovative
ways to accomplish the tasks.
• I will provide you with a variety of materials from which to choose.
• If you have questions about the exercises, reread the beginning instructions.
This strategy encourages you to figure out how to use the materials to reach
your goal.
• You have plenty of time to explore. As long as you are actively engaged, learning
is taking place. If ample time is allowed, you will be able to do more in-depth
investigation. Thinking about a problem is part of learning.
• I encourage you to share ideas with others. This strategy reflects how people
solve problems in the workplace — with input from others. Most problemsolving activities lend themselves to having you work individually, but you are
encouraged to seek others’ input.
Applied Technology • 5
BASIC PRINCIPLES
BASIC SCIENTIFIC PRINCIPLES
Applied Technology focuses on:
• Principles related to power sources – for thermal,
fluid, electrical, and mechanical systems.
• Principles related to flow – for thermal, fluid,
electrical, and mechanical systems.
• Principles related to pressure – for thermal, fluid,
electrical, and mechanical systems.
• Principles related to resistance – for thermal, fluid,
electrical, and mechanical systems.
Some basic scientific principles involved with energy
sources, flow, pressure, and resistance follow:
Bernoulli’s principle: The faster the flow of air or fluid, the lower the pressure.
Boyle’s law: For a certain amount of gas, at a constant temperature, as the pressure (P)
increases, the volume (V) of the gas decreases so that P times V is constant (k). (PV=k).
Charles’ law: For a certain amount of gas, at a constant pressure, as the absolute
temperature of the gas increases, the volume of the gas also increases. Mathematically
this is: Volume (V) divided by temperature (T) equals a constant (k). V/T=k The
temperature must be on an absolute scale that is in reference to absolute zero.
Hooke’s law: The greater the force exerted on an object, the more it will be moved. For
example, the heavier the weight hanging from a spring, the more the spring will be
stretched.
Newton’s laws of motion:
• An object will remain at rest or in uniform motion unless acted upon by an
outside force.
• When a force acts upon an object, it changes the momentum of that object,
and this change is proportional to the applied force and to the time that it acts
upon the object.
• Every action (force) is followed by an equal and opposite reaction (force).
Ohm’s law: Current is directly proportional to the voltage and inversely proportional to
the resistance.
Pascal’s law: Pressure added to a confined fluid at any point instantly appears equally at
all other points, and is always at right angles to the confining surfaces.
6 • Applied Technology
OUTLINE
LESSON 1
Thermodynamics
LESSON 2
Fluid Dynamics
LESSON 3
Electricity
LESSON 4
Mechanics
LESSON 5
Posttest
REFERENCES
Test-Taking Tips
Basic Scientific Principles
Bibliography
Answers to Pop Quiz Questions
Applied Technology • 7
LESSON 1
THERMODYNAMICS
Thermodynamics is a very complicated science.
There is a lot that can be learned about it. We are going
to review the basic concept of the topic and practice
basic problems using our acquired knowledge. The
problems at this level will be more difficult. But, don’t
worry; the principles are the same.
Remember, all matter is made up of particles that
are in constant motion. This motion manifests itself as
the form of energy called heat. The study of heat is
called thermodynamics. Now, that wasn’t so hard, was
it? There are two basic laws of thermodynamics.
Basic Laws of Thermodynamics
1. Energy cannot be created or destroyed.
2. Heat energy always flows spontaneously from
hot to cold.
My mind spontaneously
flows from cold to hot!
8 • Applied Technology
LESSON 1
Some other generalizations that can be made about heat
include:
• Heat travels through conductors such as metal better
than it travels through insulators such as brick or
wood. For example, you know that if you stir boiling
water with a metal spoon, it will soon heat up to
the point where you cannot touch it. If you stir
boiling water with a wooden spoon, you can stir it
indefinitely without it getting too hot to touch.
• Dark-colored surfaces absorb more heat than lightcolored surfaces.
• Rough or dull surfaces absorb more heat than
smooth or shiny surfaces.
• When friction causes heat, the object that is in
constant contact gets hotter than the movable
object.
In this level we will be concentrating on heating
and cooling systems. Several scientific principles are
involved in these problems including airflow, resistance,
equilibrium, and fluid pressure.
Heating and cooling systems involve a variety of
devices including compressors, shutoff valves,
thermostats, filters, ductwork, and diffusers. The
diffusers, which are usually in the ceiling or floor, direct
air into the room.
Applied Technology • 9
LESSON 1
You may think that you are totally unfamiliar with
these systems, but you probably know more than you
think! Many homes have central heat and air units.
These units have the previously mentioned parts. You
probably work with these systems often. For example,
every time you change the setting on your thermostat,
you are manipulating your system. If you open or close
a vent, you are making a change in the diffuser. If your
system quits working, you hope and pray that the
maintenance person you call doesn’t tell you that your
compressor must be replaced! Silver-colored ductwork
that is in your attic or basement directs the flow of air
into each room. What happens when your thermostat
is not functioning properly? Look out when you receive
your next electric bill! See, you do know more about it
than you thought.
Let’s look at the diagram of a cooling system that
uses a radiator instead of a compressor to provide the
cooling function.
As air passes over the radiator, it will be cooled by
the water circulating in and out of the radiator. The
blower motor forces the air through the ductwork. Air
valves, or dampers, are adjustable to regulate the airflow
into each room. In this diagram, there is one thermostat
which is set at 72 degrees. All the rooms should be at
that temperature. The volume, or total amount of air,
determines the actual room temperature.
10 • Applied Technology
LESSON 1
Diagram A
For example, if you have one of the vents wideopen in one room and one half-open in another, the
temperature in those rooms will be different. Also, a
low water level in the radiator would affect all four
rooms. Equilibrium is achieved when the airflow and
resulting temperatures even out in all four rooms to
within one degree.
Think about this process as you complete the
following exercise.
Applied Technology • 11
LESSON 1
EXERCISE – OFFICE COOLING AND HEATING
Instructions: Read the following scenario and refer to Diagram A. Then, answer the questions
pertaining to it.
Scenario
In the springtime, four offices that are controlled by the same
air-conditioning system are at different temperatures (as
indicated on the previous diagram). Some rooms have
windows, and some do not. One thermostat controls all four
rooms. As the diagram shows, each room has ductwork going
to it, which ends in an air diffuser in the ceiling of that room.
There is a circuit breaker to prevent electrical overload on
the system. Your job is to equalize the temperature in the
four rooms.
Identify the problem
1.
What is the problem?
a.
b.
c.
d.
e.
The water going into the radiator is too hot.
The temperature is different in each of the four rooms.
There are not enough windows.
The air ducts are the wrong size.
There are too many cold air ducts.
IDEAL
12 • Applied Technology
LESSON 1
2.
The problem with the system could be that:
a.
b.
c.
d.
e.
the water level is too low in the system.
the circuit breaker has tripped.
the blower system is not working correctly.
the sun coming in the window is creating the malfunction.
the thermostat is not operating.
Define the problem
3.
To identify the malfunction, first check:
a.
b.
c.
d.
e.
the water pressure.
the thermostat setting.
the bearing on the blower motor.
to see whether air is coming out of the diffusers in each room.
the circuit breaker.
Explore alternatives
4.
To isolate the problem, you would first:
a. measure airflow coming from the diffuser in each room.
b. measure the pressure drop across each filter.
c. check the water temperature before it enters and after it exits the
radiator.
d. check the voltage going to the thermostat.
e. measure the temperature outside the building.
Applied Technology • 13
LESSON 1
Act on a plan
5.
Which of the following measurements taken in the system would
indicate an existing problem?
a. The pressure drop across Filter A is 2 psi (pounds per square
inch); the pressure drop across Filter B is 2 psi.
b. Air leaving the radiator is 68°F; the temperature of the return-air
duct is 76°F.
c. The airflow rate to each room is:
Room 1 – 60 cfm (cubic feet per minute)
Room 2 – 100 cfm
Room 3 – 80 cfm
Room 4 – 85 cfm
d. The motor speed is 1,700 rpm.
e. The outside relative humidity is 90%.
Look at the result
6.
To equalize the airflow, you should change the airflow by:
a.
b.
c.
d.
e.
opening D1 and closing D2 slightly.
opening D3 and D4.
closing D3 and D4.
closing D1 and opening D2 slightly.
opening D2, D3, and D4.
14 • Applied Technology
LESSON 1
ANSWERS TO EXERCISE
1.
What is the problem?
Answer:
2.
The problem with the system could be that:
Answer:
3.
c. the blower system is not working correctly.
To identify the malfunction, first check:
Answer:
4.
b. The temperature is different in each of the four rooms.
d. to see whether air is coming out of the diffusers in each
room.
To isolate the problem, you would first:
Answer:
a. measure airflow coming from the diffuser in each room.
IDEAL
Applied Technology • 15
LESSON 1
5.
Which of the following measurements taken in the system would
indicate an existing problem?
Answer:
6.
c. The airflow rate to each room is:
Room 1 – 60 cfm
Room 2 – 100 cfm
Room 3 – 80 cfm
Room 4 – 85 cfm
To equalize the airflow, you should change the airflow by:
Answer:
a. opening D1 and closing D2 slightly.
How did you do on that problem? Did you
understand the answers? If not, go back and study the
diagram and reread the answers to figure out the
process. When you are satisfied that you understand
it, go on to the next exercise.
16 • Applied Technology
LESSON 1
This next exercise will deal with factors that affect
the flow of air, such as heat, resistance, and the effects
of fuses and breakers.
We discussed the purpose of fuses and breakers in
an earlier level of Applied Technology while discussing
electricity. You will remember that fuses and breakers
are safety devices that prevent an overload on an
electrical circuit. Overload can cause “short outs” which
can result in fire. Subsequently, you can see how fuses
and breakers would be an important device in any
system!
Pop Quiz:
Name the steps of the
IDEAL problem-solving
strategy.
Fuses and circuit breakers also can serve other
purposes. In the next example, the purpose of the fuses
and breakers is to stop the electrical current when the
preset temperature is exceeded, therefore turning off
the device and preventing overheating.
You will often encounter breakdowns in equipment
when poor ventilation exists in and around equipment.
Poor ventilation will cause the equipment to overheat,
and therefore cause damage to it.
Have you ever noticed the vents in your VCR,
television, radio, or other common appliance? If you
read the guidelines that came with the device, you
should have noticed a warning specifically stating NOT
to cover the vents and to allow space around the device.
Applied Technology • 17
LESSON 1
This is because the manufacturer wants to prevent
overheating of the equipment. If you have made the
mistake of laying the newspaper or videotapes on top
of the machine, you know what can happen! … Before
long, the machine may overheat, causing a malfunction.
Many times the machine will be ruined completely.
Heat will accumulate, even in ventilated areas, if the
equipment achieves the maximum level of activity.
Therefore, it is important for you to consider these
conditions, particularly in enclosed spaces. You must
be able to place equipment or system components
within the constraints of the workplace environment
and prevent problems with overheating. You may find
yourself in a work environment where this knowledge
will be vital.
Before we proceed to the next exercise, let’s consider
some learning activities that will help you understand
some of these principles and encourage critical thinking
on the properties of airflow.
Thinking Activity
<
Suppose you have two thermometers and a fan. Place one of the
thermometers directly into the flow of air and one below the fan where it
does not catch the breeze. What do you think will happen to the temperature
of each thermometer?
Answer: The temperatures will not change.
Did that answer surprise you? Perhaps you thought
that the breeze would cool the thermometer that was
placed in front of it. Why not?
18 • Applied Technology
LESSON 1
That is because a fan simply moves the existing air.
It does not change the temperature of the air. This is a
bit of an illusion since everyone knows that standing
in front of a fan on a hot day seems to cool you. Actually,
just the movement of the air around your body feels
cool to you because your body temperature is generally
higher than the air that is being moved. Part of this is
due to moisture that is on your body and other physical
factors.
Thinking Activity
<
<
Suppose you hold a smoking match below a fan so the smoke rises into the
path of the breeze. How do you think the smoke will move?
Answer: The smoke will move away from the fan.
Once again, this is because the air is being moved
outwardly by the movement of the blades. The smoke
will naturally go in the direction that the air is flowing.
Thinking Activity
Now suppose you hold the smoking match directly below or behind the
fan. In which direction do you think the smoke will be moved?
Answer: The smoke will be drawn up into the fan.
That is because the air behind and below the fan is
pulled up into the fan and then blown outward. Now,
let’s think about two thermometers.
Applied Technology • 19
LESSON 1
Thinking Activity
<
Suppose you wrap one of the thermometers in a wet cloth. If you hold both
thermometers in front of the fan, what do you think will happen to the
temperature of the thermometers?
Answer: The thermometer that has the wet cloth around it will be cooled.
The other thermometer will not change. Why does
this happen? The airflow created by the fan carries away
water vapor from the wet cloth. The creation of this
water vapor consumes heat, which is pulled through
the cloth from the thermometer. The heat removed
from the thermometer is shown as a reduction in its
temperature. Let’s consider an activity using heat to
illustrate airflow.
Thinking Activity
<
Suppose you have a beaker of water placed over a Bunsen burner (heat
source). What will happen?
Answer: The heat source will cause the heated water to boil causing the vapor
to rise to the top of the container.
The heat source will increase the temperature of
the water. At some temperature, the vapor pressure of
the water will be greater than the atmospheric pressure.
At this point, the water liquid turns into water vapor
bubbles. This is “boiling.” The water vapor bubbles
rise in the water since they are less dense than the
surrounding liquid water.
OK, now that we have done some critical thinking
concerning airflow, let’s solve some problems.
20 • Applied Technology
LESSON 1
EXERCISE – TRANSFORMER BOX FANS
Instructions: Read the following scenario and study the diagram. Answer the questions
pertaining to it.
Scenario
In a factory where you work, the plant temperature is
maintained at 25 degrees Celsius. An electrical box that is
mounted on the wall in the plant contains a bank of breakers
and fuses in its top portion. Two transformers are located in
the bottom area of the box. The breakers and fuses are
temperature sensitive, rated up to 40 degrees Celsius. Each
transformer can reach a temperature of 140 degrees Celsius
without being damaged. The box’s location, which is
permanent, requires the fans to be inside the box. Your job is
to install fans inside the box to maintain a safe operating
temperature for the components.
Applied Technology • 21
LESSON 1
Identify the problem
1.
What is your assignment?
a. to determine the correct position of the fans to keep components
from overheating
b. to determine where the electrical box should be placed in the
plant
c. to determine what 140 degrees Celsius is in Fahrenheit
d. to determine whether the box size is correct for the plant
e. to determine whether the vents are arranged correctly
Define the problem
2.
What is the MOST important factor to consider in order to solve this
problem?
a.
b.
c.
d.
e.
the size of the breakers and fuses
the size of the fans
the optimal airflow from the fans
the size of the vents
whether the metal of the electrical box is expanding or contracting
from the heat
Explore alternatives
3.
What is the BEST alternative for keeping the components from
overheating?
a.
b.
c.
d.
Arrange the angles of the vents.
Open the doors in the plant.
Turn one transformer off.
Arrange the fans to circulate air from the outside of the electrical
box through the box.
e. Increase the fuse size.
22 • Applied Technology
LESSON 1
Act on a plan
4.
How should the fans be arranged for optimum airflow?
a. The fans should be eliminated because they are producing heat.
b. The fans should be facing each other and should be placed at
either end of the electrical box.
c. The fans should be positioned so they point directly out of each
vent on one side of the box.
d. Both fans should draw the warm air upward over the breakers
and fuses to exit the top of the electrical box.
e. Both fans should draw the cool air downward over the breakers
and fuses to push the warmer air out of the bottom of the electrical
box.
Look at the result
5.
Once you install the fans, are the components overheating?
a. yes
b. no
IDEAL
Applied Technology • 23
LESSON 1
ANSWERS TO EXERCISE
1.
What is your assignment?
Answer:
2.
What is the MOST important factor to consider in order to solve this
problem?
Answer:
3.
c. the optimal airflow from the fans
What is the BEST alternative for keeping the components from
overheating?
Answer:
4.
a. to determine the correct position of the fans to keep
components from overheating
d. Arrange the fans to circulate air from the outside of the
electrical box through the box.
How should the fans be arranged for optimum airflow?
Answer:
24 • Applied Technology
c. The fans should be positioned so they point directly out of
each vent on one side of the box.
LESSON 1
5.
Once you install the fans, are the components overheating?
Answer:
b. no
How did you do on that exercise? If you missed
some of the questions, go back and review before you
go on to the next exercise.
Applied Technology • 25
LESSON 1
The next exercise will involve factors that affect
airflow, including heat and resistance. Let me give you
a little background prior to this exercise.
Because the manufacturing process often leaves byproducts that flow into the air, many manufacturing
plants have air filtration systems. If you are employed
in this type of environment, you may need to know
how to identify malfunctions in air filtration systems
and how to fix them.
Beware of malfunctioning air filtration systems.
ION
T
U
CA
26 • Applied Technology
LESSON 1
EXERCISE – SMOG HOG
Instructions: Read the scenario and refer to the following diagram to answer the questions
about this problem.
Scenario
Your plant produces plastics. Exhaust fumes from the
production process are collected by fume hoods and are
treated in a device called a Smog Hog. The Smog Hog must
be kept at a high temperature to operate properly. The heat in
the system is input by a forced-air furnace.
It is your job to oversee the operation of the exhaust treatment
process. You notice that the temperature of the Smog Hog
(Temp. B) has dropped below the required operating
temperature. You must correct the problem.
Applied Technology • 27
LESSON 1
Identify the problem
1.
What have you been asked to do?
a.
b.
c.
d.
e.
recondition the air
lower the temperature in the room
raise the temperature of the Smog Hog
lower the temperature of the Smog Hog
call your supervisor
Define the problem
2.
The problem is that:
a.
b.
c.
d.
e.
3.
the exhaust blower is not functioning.
the operating temperature is too low.
no fumes are being collected.
fume hood 2 is not functioning.
the operating temperature is too high.
To locate the source of the problem, which of the following should
you check FIRST?
a.
b.
c.
d.
e.
the blower motor
the natural gas supply to the furnace
the temperature at Temp. A, 1, 2, 3, and 4
the furnace filter
the exhaust air
28 • Applied Technology
LESSON 1
Explore alternatives
4.
What would be the indication of the source of the problem?
a. The furnace filter is clogged.
b. The blower motor is burned up.
c. The temperatures are as follows: Temp. 1 is 130˚F; Temp. 2 is 135˚F;
Temp. 3 is 81˚F; Temp. 4 is 129˚F.
d. The exhaust blower motor’s speed is 1,750 rpm.
e. The inlet air is hot.
Act on a plan
5.
What would you do?
a.
b.
c.
d.
e.
Open D1 slightly.
Remove the furnace filter.
Turn up the furnace temperature.
Close D3 slightly.
Open D2 slightly.
Look at the result
6.
After taking action, what would you expect to happen?
a.
b.
c.
d.
e.
Temp. A and Temp. 2 will increase.
Temp. B and Temp. 3 will increase.
The blower motor’s load will go down.
The airflow out of the exhaust will increase.
The furnace will turn off.
Applied Technology • 29
LESSON 1
ANSWERS TO EXERCISE
1.
What have you been asked to do?
Answer:
2.
The problem is that:
Answer:
3.
c. raise the temperature of the Smog Hog
b. the operating temperature is too low.
To locate the source of the problem, which of the following should
you check FIRST?
Answer:
30 • Applied Technology
c. the temperature at Temp. A, 1, 2, 3, and 4
LESSON 1
4.
What would be the indication of the source of the problem?
Answer:
5.
What would you do?
Answer:
6.
c. The temperatures are as follows: Temp. 1 is 130˚F; Temp. 2
is 135˚F; Temp. 3 is 81˚F; Temp. 4 is 129˚F.
d. Close D3 slightly.
After taking action, what would you expect to happen?
Answer:
b. Temp. B and Temp. 3 will increase. Excessive outside air is
being drawn through P3 – This has a cooling effect on
both Temp. 3 and ultimately on Temp. B.
Applied Technology • 31
LESSON 2
FLUID DYNAMICS
Ready to study fluid
dynamics?
Before we begin this lesson, let’s review some of the
basics that we discussed in earlier levels. This should
reinforce principles if you have been working with me
in previous levels of Applied Technology. If you are
starting at this level, this will help you to remember
the basics.
Some generalizations that can be made about fluids
are provided:
Concerning pressure
• The amount of pressure exerted by a fluid
depends upon the height and the density of
that fluid and is independent of the shape of
the container that is holding the fluid.
• The deeper the fluid, the greater the pressure
it exerts.
• The denser the fluid, the greater the pressure
it exerts (e.g., salt water is denser than fresh
water).
• Fluids seek equilibrium – they seek their own
level; a fluid will flow from a place of high
pressure to a place of low pressure.
• A fluid can never rise higher than its source
without an external force (e.g., a pump).
#
32 • Applied Technology
LESSON 2
Concerning evaporation
Q
• The higher a liquid’s temperature, the faster
it will evaporate.
• The lower a liquid’s pressure, the faster the
liquid will evaporate.
• The more area of a liquid that is exposed to
air, the faster the liquid will evaporate.
• The more circulation of air above a liquid,
the faster the liquid will evaporate.
Concerning boiling point
_
• Increased pressure on a liquid raises the
liquid’s boiling point.
• Decreased pressure on a liquid lowers the
liquid’s boiling point.
Principles of fluid dynamics include flow, pneumatic
(air) pressure, and hydraulic (water or oil) pressure.
Pressure can be applied in many different ways to do
work. For example, a water wheel can turn a grinder to
grind corn into meal. This principle was applied
thousands of years ago to help people accomplish work
much easier and faster. Before the invention of the water
wheel, people had to grind corn by hand to make meal.
Hand grinding also applied to wheat in order to make
flour. Just think what a work-saving device the water
wheel became to our ancestors! It allowed them to do
more in less time and with much less effort.
Applied Technology • 33
LESSON 2
Most of us have seen an old fashioned water wheel.
At a glance, you may not think that there is any pressure
involved in the operation. The water usually flows
through a flume until it reaches the wheel, where it
drops onto it, causing it to turn. The wheel then is
attached to large gears which also turn to provide the
grinding effect. You can reach down and put your hand
into the water just as it is falling onto the wheel and
feel the pressure of the water forcing your hand down.
Simple gravity is the basis of this machine.
This basic principle can also be applied using
compressed air, oil, or water to provide extreme
pressure. This type of pressure could be dangerous if
you were to be in a direct “line of fire” so to speak.
A good example of this type of compressed pressure
is a nail gun. You may have seen the force with which
the nail is driven into a board. The power is provided
by compressed air or fluid. I don’t have to explain the
danger of being exposed to a machine using this kind
of pressure. You certainly would not want to put your
hand in front of the gun! Both of the examples I have
given use the scientific principle of fluid dynamics to
make them work.
Another type of machine that is powered by
compressed air is an air driver. It is a little more
complicated than the nail gun, as it needs lubrication
in order to operate properly and be durable. To assure
that this happens, each drop of lubrication in the air
driver is fed by a lubricator that is filled with a standard
grade pneumatic oil. There may be more than one
driver in an air gun. Only one lubricator is needed for
all the drivers if the drivers do not run at the same
time. Each lubricator is fully adjustable so that drivers
are provided with proper lubrication.
34 • Applied Technology
LESSON 2
Let’s consider a couple of learning activities that
should help you understand the principle of fluid
dynamics.
Thinking Activity
<
Most every child has made a pinwheel at some time in his or her life. This
is an easy example of air pressure. All it takes is a straw, a straight pin, and
a piece of paper cut and folded into a pinwheel. If you release the air from
a balloon onto the pinwheel, the pinwheel turns.
The reason for using a balloon to provide the air
pressure is to demonstrate that air (energy) can be stored
to do work at a later time.
Thinking Activity
<
Suppose that you have several pieces of plastic PVC pipe cut into different
lengths. By constructing a simple flow pattern with the pipes, you can
direct air or water through them in many ways. By using Ts and shutoff
valves, you can direct the air or water into whichever pipe you want. Imagine
that you have a piece of tissue paper attached to one of the ends of the pipe.
By blowing through the opening or using a standard bicycle pump, you
can make the tissue flutter at the end. If you want to direct the flow of air,
you can shut off one or more of the pipes, and the air will flow along the
pipes that have remained open.
Your water pipes at home are constructed this way.
Whenever you turn on a faucet, you have opened a
valve which allows the water to flow. The water is under
pressure so that it can flow uphill.
Applied Technology • 35
LESSON 2
Thinking Activity
<
Here’s another easy demonstration of air pressure. Suppose you have an
empty dishwashing detergent bottle. Place a small amount of clay over the
nozzle end molding it tightly over the opening. Holding the bottle next to
your ear, squeeze gently to check for any air leaks around the top. Then,
laying the bottle on the floor, being careful to point it away from anyone,
jump on the bottle with all your weight. The piece of clay will be shot out
at a great speed and pressure. See why I told you to point it away from
anyone? The clay plug was driven by compressed air.
The same principle can be demonstrated using water
or oil, but it would be much messier! When air, gas, or
fluid is compressed, it exerts greater force.
Look at the following examples of compressed air,
water, and oil. You will recognize most or all of them
as common items used by people all of the time.
Pop Quiz:
As fluid depth increases, does the pressure
increase or decrease?
36 • Applied Technology
LESSON 2
Examples that show energy movement:
Air
•
•
•
•
•
•
•
Aqua-Lung (compressed air and gas)
Vacuum cleaner (reversed airflow)
Windmill (wind-driven water pump)
Forced-air furnace heating system
Pinwheel
Helicopter blades
Air line at gas station (compressed air)
Water
• Toilet tank
• Fire hose (pressurized water)
• Mill wheel (flow of water moving a grinding wheel)
• Water pipe in a home (pressurized to allow water to run uphill)
• Water tower (holds a large quantity of water as stored energy; allows
water to flow as needed)
Oil
•
•
•
•
•
•
Hydraulic jack
Car shock absorbers
Hatchback closing on a car
Dump truck
Garbage truck
Log splitter
Now that we have gone over some of the principles
concerning pneumatic and fluid pressure, let’s try a
problem using what we have learned.
Applied Technology • 37
LESSON 2
EXERCISE – MINI-OILER AIR LINE LUBRICATOR
Instructions: Read the following background information and scenario regarding an
automated teller machine (ATM) production line. Then, refer to the following
diagram to answer the questions about this problem.
38 • Applied Technology
LESSON 2
Mini-Oiler Layout
The diagram shows a filter/regulator/lubricator at every tool station of an
ATM production line. The line is powered by compressed air. Various tools
needed in the manufacturing process are attached to the coupler nipples of
the tool stations.
In order for air-driven tools to last longer and operate accurately, they must
be lubricated properly. To assure that this happens, the air driver at each
tool station is fed by a lubricator that is filled with oil. Only one lubricator
is needed for three air-driven tools, if the tools are not used at the same
time. Each lubricator is fully adjustable so that drivers are provided with
proper lubrication.
Mini-Oiler Filling Instructions
The following steps must be followed to fill the oilers and to keep adequate
oil supplied to the air drivers. NOTE: Operators should never let MiniOilers get below the empty mark.
• The air lines going into the oiler must be disconnected to perform
this activity.
• Inspect the oil base for water, foam, bubbles, etc. If any of these
substances are present, contact the maintenance department for
repair.
• Unscrew the filler screw on the top of the Mini-Oiler, under the
red cap. Add oil to the full mark. Place the filler screw back on
and tighten it.
Applied Technology • 39
LESSON 2
Scenario
You are a trained associate at a plant that produces automated
teller machines. You have been certified in the use of air
drivers, which provide power to the manufacturing line’s airdriven tools. You are responsible for using the appropriate
torque analyzer to check the torque of your air driver on a
scheduled basis or when torque valves are suspect. You must
take the average of five readings. You are responsible for
recording the results of your inspection. The torque
specification should be from 14 to 18 in lb (inch pounds).
This month’s readings on your air driver are as follows: 13.45
in lb, 12.30 in lb, 13.60 in lb, 14.25 in lb, and 12.65 in lb. In
addition you have noticed excessive heat buildup on the air
driver during the past month. It is your responsibility to
determine what the problem is and to fix it.
Identify the problem
1.
Your assignment is to:
a. replace your air driver.
b. determine the reason for the heat and low torque readings on the
air driver.
c. adjust the torque on your air driver.
d. move to another station.
e. quit for the day.
40 • Applied Technology
LESSON 2
Define the problem
2.
What do you need to consider when troubleshooting this problem?
a.
b.
c.
d.
e.
how many workstations are on the same air-supply line
whether the torque readings are in the appropriate range
the temperature outside
the grade of oil that is being used
the humidity outside
Explore alternatives
3.
To determine possible explanations for the malfunction, you should:
a.
b.
c.
d.
e.
4.
check for pipe leaks.
check the compressor.
check the oil lubricator.
ignore it and assume that the torque analyzer is bad.
obtain a fan to cool the workstation.
Of the following, which would be the most likely cause of the
problem?
a.
b.
c.
d.
e.
The relative humidity for the day is extremely high.
The lubricator lacks oil.
The are too many workstations off of the main air supply.
There is a blockage in the system piping.
You are applying too much pressure to the air driver.
Applied Technology • 41
LESSON 2
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42 • Applied Technology
LESSON 2
Act on a plan
5.
What action will you take now?
a.
b.
c.
d.
e.
Add a fan to cool the air driver.
Shut down your station and take the driver to another workstation.
Add oil to the lubricator.
Adjust the psi on the compressor.
Use a hand driver to allow your driver to cool down.
Look at the result
6.
After half an hour of using the tool, you:
a. do nothing more and assume that the torque rating is close
enough.
b. do nothing since the tool feels cooler.
c. recheck using the torque analyzer to assure that the reading falls
between 14 and 18 in lb.
d. visually inspect the hardware to make sure that it is working
properly.
e. decide that you need another fan at your workstation.
IDEAL
Applied Technology • 43
LESSON 2
ANSWERS TO EXERCISE
1.
Your assignment is to:
Answer:
2.
What do you need to consider when troubleshooting this problem?
Answer:
3.
b. The lubricator lacks oil.
What action will you take now?
Answer:
6.
c. check the oil lubricator.
Of the following, which would be the most likely cause of the
problem?
Answer:
5.
b. whether the torque readings are in the appropriate range
To determine possible explanations for the malfunction, you should:
Answer:
4.
b. determine the reason for the heat and low torque readings
on the air driver.
c. Add oil to the lubricator.
After half an hour of using the tool, you:
Answer:
44 • Applied Technology
c. recheck using the torque analyzer to assure that the
reading falls between 14 and in 18 in lb.
LESSON 2
EXPLANATION OF ANSWERS
For this exercise, I will provide some explanation about why some choices for the answers are
incorrect. I hope this is helpful to you.
1.
Correct answer: b
Why not?
a. You have been certified in the use and maintenance of the air
driver.
c. You have not been certified in adjusting torque.
d. This would cause disruption on the line and interfere with
another’s work.
e. This is an inappropriate response.
2.
Correct answer: b
Why not?
a. You are not qualified to determine this.
c. Outside temperature will not affect your driver.
d. All the torque drivers use the same grade oil.
e. Outside humidity will not affect your driver.
3.
Correct answer: c
Why not?
a. If there was a leak in the hose, other drivers would also be affected.
b. You are not empowered to do anything with the compressor.
d. You cannot ignore the problem.
e. Cooling the workstation will not affect the driver.
Applied Technology • 45
LESSON 2
4.
Correct answer: b
Why not?
a. The relative humidity will not affect the torque on your air driver.
c. The number of workstations off the main supply is within
specifications.
d. The hoses are made of fixed piping.
e. A manual tool, like a screwdriver, would not give you appropriate
torque in a consistent manner and would slow down production.
5.
Correct answer: c
Why not?
a. Adding a fan will not affect the driver.
b. This would disrupt others and close another tool station down.
d. You are not empowered to adjust the psi.
e. You will be unable to achieve the correct torque with a hand driver.
6.
Correct answer: c
Why not?
a. This would be an inappropriate action.
b. This would be an inappropriate action.
d. A visual inspection will not allow you to determine if the problem
has been corrected.
e. Another fan will not solve the problem.
46 • Applied Technology
LESSON 3
ELECTRICITY
I will present an overview of electricity so that you
can briefly review basics discussed in previous levels.
Electricity is the continuous flow of electrons, or
current, from one atom to another. No electron flow
will occur unless there is a pathway over which the
electrons can move. This flow is similar to a water
system, where pipes or hoses move water from
storage tanks to where it is needed. In electrical
wiring, the pathway through which electrical
current flows is called a circuit. A simple circuit
consists of a power source, conductors, load,
and a device for controlling current. Each is
described below.
In buildings, the power source could be the
electrical generating stations that pump electricity into
residential and commercial buildings. However, other
common sources of electrical power include small
generators and batteries.
Conductors, or wiring, provide a path for the
current so that it can travel from one point to another.
A load is a device through which electricity produces
work. For example, a lamp is a load that, when plugged
in and turned on, produces light. Other examples of
loads include heaters, electric motors, and televisions.
Applied Technology • 47
LESSON 3
Switches (on-off switches) control when electrical
current flows through circuits. Fuses and circuit
breakers are protective devices that control current by
preventing too much current from flowing in the
circuit, which would damage equipment. When an
excessive amount of electricity passes through them,
fuses and circuit breakers “blow” or “trip” to stop the
flow of electricity through the circuit.
In a circuit, resistance lowers the amount of
electrical energy available to do work. Both wires and
load affect resistance. It might be helpful to think of a
similar situation with a hose that is connected to two
sprinklers. As water passes through a hose, turns or
kinks in the pathway cause friction (which is resistance)
that results in a slower flow. In addition, when some of
the water is diverted to the first sprinkler (which is a
load), less water is available for use in the second
sprinkler.
There are two ways or methods of having current
flow. Direct current flows in one direction. In most
cases, direct current is provided to equipment by
batteries (flashlights and portable radios). Alternating
current flows in one direction, then reverses to the other
direction. Alternating current is provided to equipment
through electrical substations in buildings. In the
United States, common household current reverses
itself 60 times per second. This results in 120v 60 cycle
AC. The international reference for cycles is defined in
hertz (one hertz = 1 cycle per second).
48 • Applied Technology
LESSON 3
Measurement of electric current
The rate at which electricity flows is called
amperage. It is measured in amperes. A 100-watt bulb
requires a current of approximately 1 ampere to make
it light up completely. Current flow is measured with
an ammeter. Most electrically powered equipment
indicate the amount of current needed to operate it
properly.
Measurement of electrical pressure
Pressure is applied to electrons to force them to move
through a conductor and around a circuit. This pressure
is measured in volts. The pressure, or voltage, is
available in wiring circuits all of the time … whether
or not electrical equipment is being used. Voltage is
measured with a voltmeter.
Calculation of power
Tip: Make note of these
measurements.
The amount of power derived from an electrical
device or system is its wattage. In other words, it is the
product obtained from electrical energy; it is the power
that we put into use. For example, the electric company
sells electrical energy. Electrical energy or power is
measured in watts and can be calculated as follows:
For direct-current circuits:
volts × amperes = watts
For alternating-current circuits:
volts × amperes × power factor = watts
___________________________________________________________________
NOTE: Power factors range from 0-1. Large equipment (an electric heater) may have a
power factor as high as 1; small equipment (a small motor) may have a power factor as
low as .25.
Applied Technology • 49
LESSON 3
Ohm’s law
Ohm’s law is a simple formula used to describe the
relationship between current (flow), voltage (pressure),
and resistance of an electrical circuit. Each component
interacts to affect the operation of a circuit. In other
words, because voltage pushes current through a
resistance, a change in any of the components will result
in a change in the others. The following three equations
are Ohm’s law rearranged to solve for each of the
quantities:
Current = Voltage ÷ Resistance
amps = volts ÷ ohms
I = E/R
An increase in voltage causes an increase in
electrical current flow. An increase in circuit
resistance causes a decrease in electrical
current flow.
Voltage = Current × Resistance
volts = amps × ohms
E=I×R
An increase in current causes an increase in
voltage. An increase in resistance causes an
increase in voltage.
Resistance = Voltage ÷ Current
ohms = volts ÷ amps
R = E/I
50 • Applied Technology
LESSON 3
Generalizations that can be made about electricity:
• The longer the wire, the greater the resistance; the thinner the wire, the greater
the resistance.
• An increase in temperature of a wire causes an increase in resistance.
• An ordinary electrical cord has two wires; one for the flow of current from the
power source and the other for the return or ground.
• The voltage (pressure) and current (flow of electricity) directly affect how much
power is available to do work. Less energy source or lower flow will result in less
electrical power being produced.
• A series circuit has only one path for the flow of current. In a series circuit,
objects are placed one after another and the current flows through each of them
in succession. The current is the same throughout, however, and the voltage is
divided among the objects in the circuit.
• In a parallel circuit, there are 2 or more paths, or branches, for the flow of
current. The current will divide and flow through each of the paths
simultaneously. Every branch has the same voltage and - if the appliances are all
the same - will have the same amount of current. The total circuit resistance is
less than any one branch.
• When batteries are connected in a series, the current is the same; the total
voltage is the sum of the voltage of each battery. The terminals are connected
+, -, +, -, and so on.
• When batteries are connected in parallel, the total current is the sum of the
currents in each battery; the total voltage is the same as that of one cell. The
terminals are connected +, +, +, and -, -, -.
Applied Technology • 51
LESSON 3
Diagnostic equipment
There are many different types of test equipment
which can be used to troubleshoot electrical circuits.
The most common testers include light probes,
voltmeters, ohmmeters, ammeters, and oscilloscopes.
A handy basic tester is called a multimeter. This is a
relatively inexpensive meter that can be used to measure
resistance (ohms), voltage (AC or DC), or current
(amps). They are available with an analog or digital
readout.
To familiarize you with the use of the multimeter,
we will discuss the analog readout version. The digital
meter uses the same principles.
For the discussion, refer to Diagram B which
represents the face of a meter.
Let’s look a little closer at the meter’s operation. All
readings are taken using the test probes. The probes
are color-coded. The black probe is for the common
ground/negative connection. The red probe is for the
voltage/positive connection. The probes are inserted
in the meter.
It is imperative that the leads be in the right
receptacles. Many test readings require the correct
polarity to obtain an accurate reading. The correct
polarity is for the black probe to be placed at the more
negative point of the circuit or component being tested
and the red probe placed at the more positive point.
Testing a circuit with power on and with the test probe
polarity reversed will result in erroneous readings and
will likely damage the meter.
52 • Applied Technology
LESSON 3
It is extremely important when making the tests on
active circuits (voltage present), that the probes are held
only by the plastic insulators and that you do not
contact the metal tips. Serious electrical shock or death
could result.
The face of the meter displays several scales. The
scales include ohms, DC volts, and AC volts. The scale
used is determined by the selector switch setting.
It is important to note that while the multimeter
tester will measure current, the meter’s capacity for
reading amperage is very low. The amperage capacity
is normally in milliamps and only useful in
troubleshooting integrated and transistorized circuitry.
Power circuits, household circuits, and the large current
applications require an ammeter that has a larger
capacity. Attempting to read a high current on a
standard multimeter will damage the meter.
Diagram B
Applied Technology • 53
LESSON 3
Ohms/Resistance
Resistance, measured in ohms, is taken with the
power supply to the circuit or components turned OFF.
The first step is to place the function selector switch
in the desired position. Refer to Diagram C.
Ohms/Resistance
R×1
R×10 R×1K
Look at the scale labeled ohms and compare it to
the function selection. The needle reading at the level
of 5 on the scale with the selector on R×1 equals 5×1
or 5 ohms. The needle reading at the level of 5 with
the selector on R×10 equals 5×10 or 50 ohms. The
same reading with the selector on R×1K equals 5×1000
or 5K ohms.
Prior to making a resistance measurement, the meter
must be “zeroed.” This is accomplished by selecting the
desired meter range (R×1, etc.). The metal tips of the
probes are pressed together which creates a direct short.
This means no resistance or “zero ohms.” While holding
the tips together, the ohms adjustment is turned until
the needle reads exactly zero ohms. Now, you are ready
to make your resistance reading.
Just a couple of more tips … for the most accurate
readings, you should select the lowest possible meter
range (R1) that does not result in the meter fully
deflecting to the highest end of the scale. If the meter
reads full deflection, move to the next higher scale and
try again. Also, you should make the “zero ohms”
adjustment each time you change scales.
54 • Applied Technology
LESSON 3
Resistance measurements are taken by placing the
meter in parallel with the measured circuit or
component.
Diagram C
Applied Technology • 55
LESSON 3
Voltage
The measurement of DC (direct current) and AC
(alternating current) voltages are very similar. Proper
negative and positive polarity are critical for DC
measurements. In some AC applications, polarity is not
important; however, it is good to follow proper polarity
rules where possible.
Step one is to select the type of voltage to be read
(AC or DC) and the proper range on the function
selector. For unknown voltages, the highest range
should be selected. Locate the proper readout scale on
the meter and calculate the reading based on the range
selected. If the resulting reading fits in a lower scale,
move to that scale for a more accurate reading.
For voltage readings, the meter does not need to be
“zeroed.”
For voltage readings, the meter is placed in parallel
with the measured circuit or component. Refer to
Diagram C.
56 • Applied Technology
LESSON 3
Current/Amps
Some multimeters will measure current, however
the amperage must be very low. Following the same
steps as outlined in resistance and voltage
measurements, ensure the probes are in the proper
meter receptacles. Proper polarity is critical. Select the
current function and desired range. Always select the
highest range first and move to lower ranges as
appropriate.
Unlike the resistance and voltage measurements,
the meter must be placed in series with the test circuit.
This means the circuit must be broken and the meter
attached so the current will flow directly through the
meter.
Series
Applied Technology • 57
LESSON 3
SAFETY TIP
When working with live circuits, clip the probes to
the desired test points before applying power and
remove the power before removing the probes. If this
is not possible, clip one probe to a desired test point;
hold the insulated portion of the remaining probe with
one hand and place the metal tip at the second test
point while keeping your other hand in your pocket.
This reduces the potential of your hands touching items
that could complete an electrical path through your
body, thereby reducing the potential for accidental
electrical shock.
,
Standing on a rubber mat also reduces the possibility
of completing the circuit through your feet.
Now that we have reviewed the basics of electricity,
it’s time to try a couple of problems relating to it.
58 • Applied Technology
LESSON 3
EXERCISE – USING A VOLTMETER
Instructions: In the following exercises, assume the batteries are 1.5 volts. Turn on your
voltmeter and set it to the 5-volt DC scale.
1.
Using a battery, touch the black meter lead to the negative terminal
and the red meter lead to the positive terminal. What does the meter
read?
____________________________________________________________
2.
Reverse the meter leads. What does the meter indicate?
____________________________________________________________
3.
In this circuit, a jumper lead connects two batteries in series. What
does the meter read?
____________________________________________________________
Applied Technology • 59
LESSON 3
4.
Reverse the polarity of one of the batteries in question 3. What does
the meter read?
____________________________________________________________
5.
With one battery and one light bulb in a circuit, what is the voltage
across the light bulb? ____________________________
60 • Applied Technology
LESSON 3
6.
With two light bulbs in series with the battery, what is the voltage
across each individual light bulb?___________________________
Applied Technology • 61
LESSON 3
ANSWERS TO EXERCISE
1.
Using a battery, touch the black meter lead to the negative terminal
and the red meter lead to the positive terminal. What does the meter
read?
Answer:
2.
Reverse the meter leads. What does the meter indicate?
Answer:
3.
The meter attempts to read negative and pegs the needle to
the negative side as you now have improper polarity. Large
voltage readings with improper polarity will damage the meter.
In this circuit, a jumper lead connects two batteries in series. What
does the meter read?
Answer:
4.
You would read 1.5 volts directly across the terminals.
With batteries attached in series with proper polarity, you will
read the sum of the batteries’ voltage.
(2)1.5 volt batteries = 3.0 volts
Reverse the polarity of one of the batteries in question 3. What does
the meter read?
Answer:
62 • Applied Technology
The meter reads “0.” The batteries are connected with
improper polarity. In order for voltage to be present, you must
have a positive and negative terminal. In this case, the leads
are attached to two positive terminals.
LESSON 3
5.
With one battery and one light bulb in a circuit, what is the voltage
across the light bulb?
Answer:
6.
1.5 volts — Since you have only one component in the circuit,
the entire voltage of the battery is applied to that component.
With two light bulbs in series with the battery, what is the voltage
across each individual light bulb?
Answer:
.75 volts — In a series circuit, the applied voltage is divided
among all the components in the circuit, depending on their
resistance. With bulbs of equal resistance, each would have
.75 volts dropped for a total of 1.5 volts.
Applied Technology • 63
LESSON 3
Pop Quiz:
A circuit that has more than one path is called
a _________ circuit.
64 • Applied Technology
LESSON 3
EXERCISE – CALCULATING VOLTAGE
Instructions: Refer to the circuit shown below and use Ohm’s law to answer the questions.
1.
What is the total resistance in this circuit?
____________________________________________________________
2.
What is the current in this circuit?
____________________________________________________________
3.
What is the current through the 10Ω resistor and the 15Ω resistor?
____________________________________________________________
4.
What is the voltage drop across the 10Ω resistor?
____________________________________________________________
5.
What is the voltage drop across the 15Ω resistor?
____________________________________________________________
Applied Technology • 65
LESSON 3
ANSWERS TO EXERCISE
1.
What is the total resistance in this circuit?
Answer:
2.
What is the current in this circuit?
Answer:
3.
.24 amps each
In a series circuit, the total amps travel through each
component.
What is the voltage drop across the 10Ω resistor?
Answer:
5.
.24 amps
.24 amps = 6 volts divided by 25Ω (I = E/R)
What is the current through the 10Ω resistor and the 15Ω resistor?
Answer:
4.
25Ω
In a series circuit, total resistance equals the sum of the
resistance of all components.
2.4 volts
2.4 volts = .24 amps × 10Ω (E = I × R)
What is the voltage drop across the 15Ω resistor?
Answer:
3.6 volts
3.6 volts = .24 amps × 15Ω (E = I × R)
How did you do on that one? If you had problems,
go back, review, and try again. Remember, you are
working at your own pace, so take extra time to study
and review if you need.
66 • Applied Technology
LESSON 3
EXERCISE – CIRCUIT PREDICTIONS
Instructions: Study the following diagram and answer the related questions.
1.
Predict what will happen when one bulb is removed from the socket.
Prediction: ______________________________________________
2.
Predict what will happen when one bulb is removed from the circuit
and the circuit is reconnected.
Prediction: ______________________________________________
3.
Predict what will happen when the fuse is removed and the circuit
is reconnected.
Prediction: ______________________________________________
Applied Technology • 67
LESSON 3
4.
Predict what will happen when the fuse is replaced with a burnedout fuse.
Prediction: ______________________________________________
5.
Predict what will happen when the resistor is removed and the circuit
is reconnected.
Prediction: ______________________________________________
6.
Predict what will happen if the operational resistor is replaced with
a burned-out resistor.
Prediction: ______________________________________________
In Diagram D, a circuit has been built similar to the diagram used earlier in this exercise.
The circuit is the same, but a parallel branch with one bulb has been added.
Diagram D
68 • Applied Technology
LESSON 3
7.
Predict what will happen if Bulb 4 is removed from the socket.
Prediction: ______________________________________________
8.
Predict what will happen if Bulb 1 is removed from the socket.
Prediction: ______________________________________________
9.
In the space provided, summarize what you learned about electrical
systems from the activities included in the exercise. If you are unsure
about the accuracy of your answers for questions 1–8, review the
answers to the exercise before completing your summary.
____________________________________________________________
____________________________________________________________
____________________________________________________________
____________________________________________________________
____________________________________________________________
____________________________________________________________
Applied Technology • 69
LESSON 3
ANSWERS TO EXERCISE
1.
Predict what will happen when one bulb is removed from the socket.
Answer:
2.
Predict what will happen when one bulb is removed from the circuit
and the circuit is reconnected.
Answer:
3.
There is no change. The lights burn. The fuse has no electrical
function beyond being a circuit safety function.
Predict what will happen when the fuse is replaced with a burnedout fuse.
Answer:
5.
The two bulbs burn brighter. The circuit voltage divides across
all resistance in a series. The removal of one bulb creates a
higher voltage applied to the remaining components.
Predict what will happen when the fuse is removed and the circuit
is reconnected.
Answer:
4.
All of the bulbs go out. There is only one path for current and
that path has been broken.
No current flows and nothing lights. The circuit is open.
Predict what will happen when the resistor is removed and the circuit
is reconnected.
Answer:
70 • Applied Technology
Lights will burn brighter depending on the size of the resistor.
LESSON 3
6.
Predict what will happen if the operational resistor is replaced with
a burned-out resistor.
Answer:
7.
Predict what will happen if Bulb 4 is removed from the socket.
Answer:
8.
Bulbs 1, 2, and 3 burn.
What happens when Bulb 1 is removed from the socket?
Answer:
9.
No current flows and nothing lights. The circuit is open.
Bulbs 2 and 3 go out. Bulb 4 burns.
In the space provided, summarize what you learned about electrical
systems from the activities included in the exercise. If you are unsure
about the accuracy of your answers for questions 1–8, review the
answers to exercise before completing your summary.
Answers will vary.
How well did you predict?
Applied Technology • 71
LESSON 3
EXERCISE – MACHINE INDICATOR LIGHTS
Instructions: Read the scenario and refer to the following diagram to answer the questions
about this problem.
Scenario
You are the maintenance person at a plant. Part of your
responsibility is to check the indicator lights on all machinery.
For safety reasons, indicator lights must be lit while the
machines are running. As you walk through the plant, you
notice that a machine is running, but its indicator light is out.
You take voltage measurements across the various
components V1, V2, V3, and V4, as indicated on the following
schematic. It is your responsibility to determine the problem
and correct it.
72 • Applied Technology
LESSON 3
Identify the problem
1.
What is your assignment?
a.
b.
c.
d.
to determine if the power supply is good
to determine the size of the lamp
to determine the size of the motor
to determine the reason why the indicator light is out although
the machine is on
e. to determine the length of the wire from the motor to the lamp
Define the problem
2.
What do you need to consider to solve this problem?
a.
b.
c.
d.
e.
the wattage of the lamp
which circuit is involved with the lamp being out
the size of the power supply
the size of the fuse
the gauge of the wire
Explore alternatives
3.
Does your voltage reading correspond with what should be
happening if there is current flowing through each device?
a.
b.
c.
d.
e.
Zero voltage across the fuse indicates the fuse is the problem.
Twelve volts across the resistor indicates the resistor is open.
Zero volts across the lamp indicates the light is bad.
The fuse is bad because there is no current.
The DC supply in not functioning.
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LESSON 3
Remember to use …
IDEAL
… for solving problems.
74 • Applied Technology
LESSON 3
Act on a plan
4.
What is the appropriate action to correct the problem?
a.
b.
c.
d.
e.
Replace the resistor.
Replace the lamp.
Replace the fuse.
Buy a new motor.
Buy a new power supply.
Look at the result
5.
Does the indicator light work?
a. yes
b. no
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LESSON 3
ANSWERS TO EXERCISE
1.
What is your assignment?
Answer:
2.
What do you need to consider to solve this problem?
Answer:
3.
b. Twelve volts across the resistor indicates the resistor is
open.
What is the appropriate action to correct the problem?
Answer:
5.
b. which circuit is involved with the lamp being out
Does your voltage reading correspond with what should be
happening if there is current flowing through each device?
Answer:
4.
d. to determine the reason why the indicator light is out
although the machine is on
a. Replace the resistor.
Does the indicator light work?
Answer:
76 • Applied Technology
a. yes
LESSON 4
MECHANICS
This is our last lesson in this level of Applied
Technology. How have you been doing so far? Do you
understand the basic idea of the lessons? I sure hope
so. If not, when you finish, go back and review all that
you need to. I don’t mind waiting!
First, let’s review basic mechanics just as we have
done in all the other lessons. This will include some
generalizations that can be made about mechanics as
well as a description of the simple machines that we
have discussed earlier.
This is mainly for the benefit of students who are
just starting this course at this level, but for all of you
who have been with me from the beginning, it will be
a good review.
A machine is something that does work.
What basic machine principle am I using? You will
find the answer as you review the basics.
Applied Technology • 77
LESSON 4
Work is done when a force causes an object to move.
Simple machines (gears, pulleys, inclined planes,
levers, wheel and axle), when used together, make up
compound (or complex) machines.
Examples of compound machines include a bicycle,
a rod and reel, a typewriter, a can opener, scissors, a
hand drill, a car, a weight machine, and a treadmill.
Gears
• The force that is applied to a driver gear is
transferred to a driven gear.
• When two gears of different sizes are meshed
together, the smaller gear turns faster (more
rotations per minute) than the larger gear.
• Gears that are meshed together move in opposite
directions.
• The direction and speed of the driver gear
determines the speed and direction of gears that
are meshed with it.
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LESSON 4
Pulleys
• A pulley is a wheel with a rope, belt, or chain around
it.
• Pulleys change the direction of movement and make
work easier.
• Fixed pulleys change the direction that something
is moved; they do not make work easier.
• Movable pulleys change the direction that
something is moved and make work easier.
• The more pulleys in the system, the easier it is to
do work (pull or lift an object).
• The more pulleys involved in a system, the greater
distance must be pulled, but the easier it is to do
work.
• The thinner the windlass (winch), the easier it is to
turn.
• In two different sets of pulleys, if the wheels are
connected by a shaft and the two wheels on one
pulley are the same size as the two wheels on the
other pulley, they will both turn at the same speed.
• Common pulley applications include crankshafts,
sailboats, boat lifts, and window blinds.
Inclined Planes
• An inclined plane is a slanted surface that is used to
raise or lower heavy objects from one position to
another.
• Inclined planes help reduce the amount of force
needed to do a given amount of work, but require
greater distance.
• The steeper the plane, the more difficult the work.
• *Wedges are two back-to-back inclined planes.
• Common inclined plane applications include
*screws, bolts, drill bits, clamps, car jacks, loading
ramps, and screw-on bottle tops.
*Some textbooks refer to the wedge and screw as basic simple machines.
Applied Technology • 79
LESSON 4
Levers
• A lever is a bar or rod that is free to move or turn
on a fulcrum.
• A lever multiplies force, but some distance must be
given up.
• The shorter the effort arm, the less force is attained
and the greater distance is attained.
• The longer the effort arm, the more force is attained
and the less distance is attained.
• Examples of levers include scissors, a broom, a claw
hammer, a nutcracker, a mop, tongs, a crowbar, a
can opener, tweezers, a baseball bat, boat oars, and
a car jack handle.
Wheel and Axle
• A wheel and axle is like a spinning lever (an ice
cream machine crank).
• The center of the axle is the fulcrum.
• The wheel is larger than the axle; for one rotation,
a point on the edge of the wheel travels a greater
distance than a point on the axle. While the work
done by the axle and the wheel are the same, the
greater distance traveled of the point on the edge of
the wheel yields a smaller force at the edge of the
wheel versus the edge of the axle.
• Common wheel and axle applications include a
screwdriver, roller skates, a water-faucet handle, a
bicycle pedal, a can opener, and a car steering wheel.
80 • Applied Technology
LESSON 4
Internal Combustion Engines
Internal combustion engines are examples of
compound/complex machines. Many different
applications of simple machines occur in the engine.
Internal combustion engines take input energies and
convert them to an energy output to do work. Examples
of common uses of the engine include the automobile,
lawn mower, gasoline-powered trimmers, gasolinepowered blowers, and gasoline-powered generators.
For our discussion, we will be featuring the fourcycle engine found on most lawn mowers. This is a
fairly simple engine; however, the same principles apply
to more complex applications such as the automobile.
We will omit several components from our
illustrations to focus on the base operations. However,
you should be aware that they exist and will be located
on the engine. Most owner manuals will provide
illustrations to help locate these components. They
include the gas tank, fuel filter, air filter, oil filter, oil
fill and crankcase, muffler, etc.
OK, let’s take a look at the logic behind the internal
combustion engine. We are going to cause a small
explosion inside an airtight cylinder. The explosion is
created by firing a spark plug in a mixture of gas and
air. This explosion and the expanding gases will push a
piston down in the cylinder. The piston is attached to
a crankshaft which is turned as a result of the piston
movement. The turning crankshaft provides the power
output to operate transmissions, pulleys, or other
devices.
Let’s look closer at the four cycles or four strokes of
a four-cycle engine.
Applied Technology • 81
LESSON 4
1. Intake stroke – the intake valve is opened and
the downward movement of the piston draws
in an air-fuel mixture from the carburetor.
2. Compression stroke – as the camshaft rotates,
the intake valve is closed. The piston is pushed
back up the cylinder and compresses the air-fuel
mixture.
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LESSON 4
3. Power stroke – the spark plug ignites the fuel
mixture, forcing the piston down. The piston
movement turns the crankshaft.
4. Exhaust stroke – Momentum drives the piston
in an upward direction in the cylinder. The
exhaust valve is opened and the burned gases
are forced out.
Applied Technology • 83
LESSON 4
In order to provide output power to the crankshaft,
this four-cycle process must be repeated very rapidly.
Also, different functions within the process must occur
in the right cycle and at exactly the right time.
The important timing considerations are the firing
of the spark plug and the opening and closing of the
intake and exhaust valves. For example, firing of the
spark plug during the exhaust cycle would result in a
misfire. Sufficient fuel would not be present for
detonation … any force developed would escape
through the exhaust valve and force could not be exerted
on the piston as it is its lower position.
Proper timing is achieved through the use of gears
and cams on a camshaft. A cam is an irregular lobe
machined on a camshaft. The projection and other
portions of the cam are used to control the time and
duration of repetitive operations in a machine.
Let’s look at the opening and closing of the intake
or exhaust valve under control of a cam.
84 • Applied Technology
LESSON 4
In Figure 1, the valve is closed as the lobe approaches
the valve operating link.
Figure 1
In Figure 2, the lobe has pushed the valve open.
Figure 2
In Figure 3, the lobe has moved past the valve and the
spring on the operating link has closed the valve.
Figure 3
Applied Technology • 85
LESSON 4
Several cams with different shapes can be located
on a single camshaft to control different functions at
different times of the cycle.
The cams controlling the intake and exhaust valves
would be on the same shaft and be similar in shape.
However, the lobes would be spaced differently to
activate the valves independently at the proper time.
The camshaft is driven by the crankshaft. The
crankshaft will make two revolutions as the engine goes
through its four cycles while the camshaft will go
through one revolution. This is accomplished by
gearing from the crankshaft.
The firing of the spark plug is also controlled by
cams. A high voltage charge is developed through the
ignition coil. This voltage is applied to the spark plug
by the opening and closing of ignition points that act
as a switch. A cam operates the points to open and
close them at the correct time.
86 • Applied Technology
LESSON 4
OK, let’s review the sequence of operation.
1. On the intake stroke, the intake valve is opened by the cam on the camshaft
and the downward movement of the piston draws in the air-fuel mixture from
the carburetor. The cam operating the exhaust valve is on the low side of the
cam, so the exhaust valve is closed.
2. On the compression stroke, the cam operating the intake valve has moved to
the low side of the cam and the intake valve is closed. The cam controlling the
exhaust valve is still on the low side and the exhaust valve remains closed. The
piston moves back up the cylinder and compresses the air-fuel mixture.
3. On the power stroke, both intake and exhaust valve control cams are at the
low point and both valves remain closed. The ignition points close, driven by
the ignition cam. A high voltage is developed through the ignition coil and is
applied to the spark plug. A spark jumps across the gap of the spark plug,
igniting the fuel mixture. The piston is forced down rapidly by the explosion
and expanding gases. The connecting rod between the piston and crankshaft
causes the crankshaft to turn.
4. On the exhaust stroke, the exhaust valve is opened by the cam. The intake
valve remains closed. Momentum drives the piston upward in the cylinder
and the burned gases are forced out the exhaust valve.
5. Work output occurs through the turning of the crankshaft.
Applied Technology • 87
LESSON 4
As I indicated earlier, the principles of operation
for an automobile engine are the same as what you
have just learned. An automobile engine may have four,
six, eight, or twelve cylinders functioning the same as
the single cylinder we have been studying. All the
cylinders will be connected to and driving the same
crankshaft. The linkage and timing of the cylinder
operation is designed to drive the crankshaft with
maximum efficiency and power.
The automobile engine will obviously have more
sophisticated controls and timing devices than a single
cylinder engine. These include computer chips and
electronic devices to control fuel mixtures, pollution
control components, ignition, accessories, and many
other marvels of today’s automobile.
Another major difference in engines is the cooling
systems. Smaller engines are air cooled with heat being
dissipated through fins on the engine. The multiple
cylinders of larger engines create more heat and require
additional cooling. Most larger engines like those used
in automobiles are water cooled.
Water-cooled engines circulate a mixture of water
and antifreeze/coolant through the engine block under
control of a thermostat. The coolant mixture passes
through the radiator where it is cooled by the radiator
fan and outside air. The thermostat senses the engine
temperature and allows enough coolant to pass to
maintain the optimum operating temperature.
88 • Applied Technology
LESSON 4
In the summer, after the engine has warmed up,
the thermostat will normally be wide-open and provide
maximum cooling. During the winter, the thermostat
may be only partially open to allow the engine to
maintain the best operating temperature.
+
Our first problem will be focusing on identifying
logical cause for the mechanical failure of an engine
when given a specific set of circumstances. This will
help you identify the best course of action to fix a
mechanical problem and to examine the effectiveness
of your work.
Many times it is difficult to see the relationship of
one component to an entire mechanical system … in
other words to see “the big picture.” Our first problem
will help you understand the effect that valves have on
an engine system. You will be asked questions that
require you to use logic.
Applied Technology • 89
LESSON 4
EXERCISE – LAWN MOWER START-UP
Instructions: Read the scenario and study the following diagram to answer the questions
about this problem.
Scenario
You work at a local lawn mower repair shop. One day, a
customer brings in her lawn mower and explains that it will
not start. She has already checked the fluid levels and
determined that the spark plug is in working order. When she
pulls the start cord, however, it seems to pull too easily, as
though there is very little resistance. What can be done to
restore the lawn mower to working order? Use the diagram
as needed.
90 • Applied Technology
LESSON 4
Identify the problem
1.
What is the problem?
a. It is too difficult for the customer to pull the cord properly.
b. The lawn mower will not start.
c. The customer wants to be able to start her lawn mower by using
a key instead of a start cord.
d. The lawn mower brand is not the brand the customer is used to
operating.
e. The length of the start cord must be at least 15 feet.
2.
Why doesn’t the lawn mower start?
a.
b.
c.
d.
e.
It has no fuel to power the engine.
It has no oil to lubricate the engine.
There is little resistance on the start cord.
The spark plug needs to be replaced.
The customer lacks the strength to make the engine turn over
fast enough when she pulls the start cord.
Define the problem
3.
Why doesn’t the start cord have enough resistance?
a.
b.
c.
d.
e.
The start cord is broken in two.
The engine has too much oil.
The start cord has become frayed from wear and tear.
There is no engine compression.
There is no engine lubricant.
Applied Technology • 91
LESSON 4
Explore alternatives
4.
If the engine’s valves were stuck open, the effect would be as follows:
a. The engine would run but not as efficiently.
b. The piston would not move up and down.
c. The start cord would pull with little resistance; the crankshaft
would move the piston up and down, but there would be no
compression; and the engine would not start.
d. The start cord would pull with great resistance; the crankshaft
would move the piston up and down, and the engine would have
compression and start.
e. The open valves would result in higher engine performance.
Act on a plan
5.
Assuming there is nothing wrong with the starting-cord mechanism,
what would be your first step in determining why the start cord has
little resistance?
a.
b.
c.
d.
e.
Check the tightness of all engine bolts.
Dismantle the lawn mower engine to explore possible problems.
Do an engine compression test.
Make sure the lawn mower has the blade attached.
Check to be sure the throttle is in the “run” position.
92 • Applied Technology
LESSON 4
6.
Which of the following causes would be the MOST accurate reason
the engine has no compression?
a. The intake and exhaust valves are closed while the piston is
traveling upward during the compression stroke.
b. The intake valve is open and the exhaust valve is closed while
the piston is traveling upward during the compression stroke.
c. There is corrosion on the outside of the engine.
d. The intake valve is open and the exhaust valve is closed while
the piston is traveling downward during the intake stroke.
e. The engine appears old and outdated.
Look at the result
7.
After repairing stuck valves and reassembling the engine, what
should you do next?
a. Immediately call the customer and tell her the lawn mower is fixed.
b. Ask your boss for a pay raise for a job well done.
c. Using a tension indicator, test the start cord to make sure it has
proper resistance.
d. Test mow a patch of lawn at least 150´ by 150´.
e. Test the engine compression, then start the mower to make sure
it works.
Applied Technology • 93
LESSON 4
ANSWERS TO EXERCISE
1.
What is the problem?
Answer:
2.
Why doesn’t the lawn mower start?
Answer:
3.
d. There is no engine compression.
If the engine’s valves were stuck open, the effect would be as follows:
Answer:
5.
c. There is little resistance on the start cord.
Why doesn’t the start cord have enough resistance?
Answer:
4.
b. The lawn mower will not start.
c. The start cord would pull with little resistance; the
crankshaft would move the piston up and down, but there
would be no compression; and the engine would not start.
Assuming there is nothing wrong with the starting-cord mechanism,
what would be your first step in determining why the start cord has
little resistance?
Answer:
94 • Applied Technology
c. Do an engine compression test.
LESSON 4
6.
Which of the following causes would be the MOST accurate reason
the engine has no compression?
Answer:
7.
b. The intake valve is open and the exhaust valve is closed
while the piston is traveling upward during the compression
stroke.
After repairing stuck valves and reassembling the engine, what
should you do next?
Answer:
e. Test the engine compression, then start the mower to make
sure it works.
IDEAL
Applied Technology • 95
LESSON 4
Spatial visualization involves the ability to
manipulate and mentally rotate two-dimensional and
three-dimensional objects. Spatial orientation involves
the ability to perceive the elements in a pattern, to
compare patterns, and to grasp changing orientation
in space. Whew, that sounds like a lot, doesn’t it? But
really it’s not that difficult when you break it down to
something with which you are familiar.
}
Take a child’s square building block, for example.
When you hold it in your hand, you can rotate it in
any direction, and you can see the three-dimensionality
of it. The only difference is that you must “see” this in
your mind when you are looking at a square block on
a piece of paper (probably in two-dimensions).
Patterns and elements in a pattern are easily
demonstrated by a multicolored Rubic’s cube.
Remember those? They were a huge fad a few years
ago. I think every household in America owned at least
one. I know I did!
See, you already know what I mean, don’t you?
That’s because you have experience with them. These
types of spatial skills are highly correlated with the
success you can achieve in a number of technical and
professional employment situations. Spatial orientation
is necessary to have a good sense of direction for tasks
such as reading schematics, diagrams, or even maps.
96 • Applied Technology
LESSON 4
Let’s complete a learning activity. See if you have
ever had to do something like this. I’ll bet you have!
Thinking Activity
<
Suppose you are moving and you have to load a refrigerator, an empty
dresser, and various boxes of miscellaneous items into a truck. Which would
you load first? Why?
Here’s what I would do. Compare your answer with
mine.
I would load the refrigerator first, placing it against
the wall near the cab of the truck. This places the weight
forward of the rear axle. By placing the refrigerator in
the center of the wall, rather than against a left or right
wall, you will distribute the weight. This will prevent
the vehicle from being difficult to handle.
Then, I would load the next biggest item, the empty
dresser, in one of the back corners. I would fit the boxes
and other miscellaneous items around the larger ones
for the best stability and least movement. Heavier boxes
should go on the opposite side of the dresser as much
as possible in order to balance the weight of the dresser.
Let’s try an exercise.
Applied Technology • 97
LESSON 4
EXERCISE – TRUCK LOADING
Instructions: Read the following scenario and answer the questions considering spatial
orientation.
Scenario
You are an employee working in the shipping department on
the shipping dock. You are instructed to package a 3˝ x 6˝ x 2´
part into a carton. It can go into the carton in any way. You are
asked to find the carton that will result in the least wasted
space and to assemble it to pack the part. Cartons are stacked
flat for storage. You are to add this box to the balance of the
day’s production. You are then to load the truck. You have 10
skids to load. They are all the same size, but they are different
weights. The skids will fill a truck when stacked 2 skids wide
and 5 skids deep. A truck backs into the dock, ready to load.
You must determine which size of box to use and the best
method for loading the truck.
Identify the problem
1.
What is your assignment?
a.
b.
c.
d.
You must order cartons from the supplier.
You are to direct customers to the back room.
You are to package a part.
You must find and assemble a carton, pack a part, and load a
truck.
e. You must operate a forklift and train a helper in its use.
98 • Applied Technology
LESSON 4
Define the problem
2.
What do you need to consider when completing your assignment?
a. You must assemble a carton to accommodate a 3˝ x 6˝ x 2´ part
and send it abroad.
b. You need to determine the exact size of the carton, load a skid,
and complete the shipping label.
c. You must locate and assemble a carton of the proper size, pack
the part, and load a balanced truck.
d. You must load a truck for shipping.
e. You must contact the shipping department before loading the
truck.
Explore alternatives
3.
Which sequence of events will help you achieve your goal?
a. Change the 2´ to 24˝; locate the approximately sized box; assemble
the carton; pack the item in the carton; and add the box to the
last skid.
b. Select a carton; package the part; arrange the skids so that the
weights are balanced on each side of the truck; and load the truck.
c. Change the 2´ to 24˝; give the part to a helper to pack; and load
the truck.
d. Put all the dimensions in the same denomination; select a flat
carton that, when assembled, will accommodate the part;
assemble the carton and pack the part; add the carton to the
day’s production; and load the skids so that the weights are
balanced on each side of the truck.
e. Wrap the part in brown paper; and load the truck with the skids in
numerical order.
Applied Technology • 99
LESSON 4
Act on a plan
4.
From the choices below, select the MOST appropriately sized box
and assemble it by folding the creased lines.
a.
b.
c.
d.
e.
Box A is the best box to use.
Box B is the best box to use.
Box C is the best box to use.
Box D is the best box to use.
None of the boxes is the right size.
100 • Applied Technology
LESSON 4
5.
From the following select the MOST appropriately arranged
configuration to load into the truck.
a.
b.
c.
d.
e.
Truckload A is best.
Truckload B is best.
Truckload C is best.
Truckload D is best.
None of the configurations will work.
Look at the result
6.
Does the item fit into the box?
a. Yes, the part fits into the box.
b. No, the part is too big for the box.
Applied Technology • 101
LESSON 4
7.
How can you determine whether the truck is loaded in a balanced
manner?
a. Load only the center of the truck, and leave the sides empty to
ensure balance.
b. Visually inspect the truck to see whether it leans to one side.
c. No check is necessary.
d. Drive the truck to a weigh station on the highway and weigh the
truck.
e. Add up the total weights on each side of the truck.
IDEAL
102 • Applied Technology
LESSON 4
ANSWERS TO EXERCISE
1.
What is your assignment?
Answer:
2.
What do you need to consider when completing your assignment?
Answer:
3.
d. Put all the dimensions in the same denomination; select a
flat carton that, when assembled, will accommodate the
part; assemble the carton and pack the part; add the carton
to the day’s production; and load the skids so that the
weights are balanced on each side of the truck.
From the choices below, select the MOST appropriately sized box
and assemble it by folding the creased lines.
Answer:
5.
c. You must locate and assemble a carton of the proper size,
pack the part, and load a balanced truck.
Which sequence of events will help you achieve your goal?
Answer:
4.
d. You must find and assemble a carton, pack a part, and
load a truck.
c. Box C is the best box to use.
From the following select the MOST appropriately arranged
configuration to load into the truck.
Answer:
a. Truckload A is best.
Applied Technology • 103
LESSON 4
6.
Does the item fit into the box?
Answer:
7.
a. Yes, the part fits into the box.
How can you determine whether the truck is loaded in a balanced
manner?
Answer:
e. Add up the total weights on each side of the truck.
How did you do? If you had trouble, go back and
review to help reinforce the concept. Then, let’s move
on to our next problem.
The focus of this exercise is to help you to identify
the logical cause for mechanical failure of a conveyor
system. It will also help you identify the course of action
to fix a mechanical problem and to examine the
effectiveness of your work.
As I mentioned before, sometimes it is difficult to
see the “big picture” of a system, or how one component
relates to an entire mechanical system. Our next
problem should help you gain an understanding of the
effect of temperature changes on the functioning of a
mechanical system.
104 • Applied Technology
LESSON 4
EXERCISE – PELLET-TRANSFER SYSTEM
Instructions: Read the following scenario and answer the related questions. There is no
diagram provided with this problem. This will give you an opportunity to
draw a diagram that fits the description provided in this problem.
Scenario
A long pan is used to convey pellets a horizontal distance …
from the silo to the hoppers. The pan vibrates to move the
contents. The vibration is set up by an attached vibrating
shaker drive. This drive rotates weights in opposite directions
by gearing. Alignment of the gearing is held by keys in
keyways in the driveshaft. This driveshaft is driven by an
electric motor. The side of the conveyor has a “V” symbol
mounted on it, which indicates the degree of horizontal
vibration. The technician determines the degree of horizontal
vibration by observing the visual overlap of the sides of the
“V” while the conveyor is moving.
You are the technician responsible for making sure that the
pellet-transfer system operates properly. You observe that the
conveyor is vibrating, but it is not moving pellets. You need
to determine why the contents are not being moved.
Applied Technology • 105
LESSON 4
Identify the problem
1.
What is your assignment?
a.
b.
c.
d.
e.
to clean the conveying pan
to check the drive motor load
to find out why the material does not convey
to replace the vibrating conveyor with a belt
to replace the conveying pan
Define the problem
2.
How can the problem be described?
a.
b.
c.
d.
e.
The motor does not run.
The conveyor does not vibrate.
The motor runs too fast.
The conveyor vibrates, but the material does not move.
The motor runs too slowly.
Explore alternatives
3.
What are the possible causes?
a.
b.
c.
d.
e.
The conveyor is vibrating improperly.
The drive motor is burned up.
The conveyor is too long.
The conveyor is too short.
The drive motor stopped.
106 • Applied Technology
LESSON 4
Act on a plan
4.
What would you do to check to see if the vibration has been
disrupted?
a.
b.
c.
d.
Check the motor load.
Check the moisture of the contents.
Measure the length of the conveyor.
Check the shaker drive’s mounting; verify that both weights are
rotating in opposite directions.
e. Check the motor rpm.
Look at the result
5.
You found one weight rotating; the other weight sheared its key and
is not moving. What would you do?
a.
b.
c.
d.
e.
Replace the motor.
Lubricate the bearings; spin the driveshaft.
Dry the pan contents; replace the pan.
Replace the sheared key; check vibration and material movement.
Check the vibration of the pan.
IDEAL
Applied Technology • 107
LESSON 4
ANSWERS TO EXERCISE
1.
What is your assignment?
Answer:
2.
How can the problem be described?
Answer:
3.
a. The conveyor is vibrating improperly.
What would you do to check to see if the vibration has been
disrupted?
Answer:
5.
d. The conveyor vibrates, but the material does not move.
What are the possible causes?
Answer:
4.
c. to find out why the material does not convey
d. Check the shaker drive’s mounting; verify that both weights
are rotating in opposite directions.
You found one weight rotating; the other weight sheared its key and
is not moving. What would you do?
Answer:
d. Replace the sheared key; check vibration and material
movement.
108 • Applied Technology
LESSON 5
Well, that’s it for Level 5 except for the Posttest, of
course! When you are ready and you have reviewed the
material, go ahead and try the test. I know you’ll do
well!
Don’t peek at the answers!
Applied Technology • 109
POSTTEST
EXERCISE – POSTTEST
Instructions: Using the knowledge you gained in this level of Applied Technology, answer
the following questions.
1.
Bernoulli’s principle states that the faster the flow of air or fluid, the
(lower, higher) the pressure. (Circle the correct word.)
2.
All matter is made up of particles that are in _____________________.
3.
Newton’s third law of motion states that for every action there is
____________________________________________________________.
4.
The study of heat is called:
a. hydraulics
b. thermodynamics
c. pneumatics
5.
Name two devices that are components of a heating and cooling
system.
____________________________________________________________
____________________________________________________________
6.
What is a diffuser in relation to heating and cooling systems?
____________________________________________________________
110 • Applied Technology
POSTTEST
7.
The total amount of air that determines the room temperature is
called _________________________.
8.
What is the purpose of the blower motor?
____________________________________________________________
____________________________________________________________
9.
What is the purpose of the thermostat?
____________________________________________________________
____________________________________________________________
10. _____________________ is achieved when the temperature in all
rooms are equal within one degree.
11. Besides protecting from electrical overload, what is another purpose
of fuses and circuit breakers?
____________________________________________________________
____________________________________________________________
12. What is the purpose of vents in a piece of equipment?
____________________________________________________________
____________________________________________________________
Applied Technology • 111
POSTTEST
13. What does the fan in a computer do?
____________________________________________________________
____________________________________________________________
14. A fan moves the air around the room, but it does not actually cool
the air. True or False?
15. Heat always stays near the floor while cooler air rises to the ceiling.
True or False?
16. Another word for pneumatic pressure is _______________.
17. Water or oil pressure is called _________________.
18. What benefit does compressed air provide?
____________________________________________________________
____________________________________________________________
19. A water flow system has ________________________ to control and
direct the flow of water.
112 • Applied Technology
POSTTEST
20. In a home water system, when you open all the faucets, what will
happen?
____________________________________________________________
____________________________________________________________
____________________________________________________________
21. Current that flows in only one direction is called:
a. alternating current
b. direct current
22. The rate at which current flows is called:
a. voltage
b. amperage
c. wattage
23. The amount of power derived from an electrical device is:
a. voltage
b. amperage
c. wattage
24. Pressure is applied to electrons to force them through a conductive
material. This pressure is measured in:
a. volts
b. amps
c. watts
Applied Technology • 113
POSTTEST
25. Name at least three simple machines.
____________________________________________________________
____________________________________________________________
____________________________________________________________
26. A ________________ machine is one that is made up of more than
one simple machine.
27. Give two examples of a compound or complex machine.
____________________________________________________________
____________________________________________________________
28. A ______________________ is something that does work.
29. A machine that consists of two inclined planes placed back to back
is called a ____________________.
30. The center of an axle is called the:
a. lever
b. hub
c. fulcrum
114 • Applied Technology
POSTTEST
31. How would you load a truck with the following items: piano, dresser,
four chairs, assorted boxes?
____________________________________________________________
____________________________________________________________
____________________________________________________________
32. Why would positioning be important in the previous question?
____________________________________________________________
____________________________________________________________
____________________________________________________________
33. ________________ ________________ involves the ability to
manipulate and mentally rotate two- and three-dimensional
objects.
34. A window blind is an example of:
a. gear
b. inclined plane
c. pulley
35. A wood screw is an example of:
a.
b.
c.
d.
gear
lever
inclined plane
wedge
Applied Technology • 115
POSTTEST
ANSWERS TO EXERCISE
1.
Bernoulli’s principle states that the faster the flow of air or fluid, the
(lower, higher) the pressure.
Answer:
2.
All matter is made up of particles that are in ________________.
Answer:
3.
an equal and opposite reaction
The study of heat is called:
Answer:
5.
constant motion
Newton’s third law of motion states that for every action there is
______________________________.
Answer:
4.
lower
b. thermodynamics
Name two devices that are components of a heating and cooling
system.
Answer:
Any two of the following:
compressor
shutoff valve
diffusers
filters
ductwork
blower
condenser
evaporator
thermostat
116 • Applied Technology
POSTTEST
6.
What is a diffuser in relation to heating and cooling systems?
Answer:
7.
The total amount of air that determines the room temperature is
called _________________________.
Answer:
8.
volume
What is the purpose of the blower motor?
Answer:
9.
A vent usually placed in the ceiling or flooring that allows
airflow adjustment.
The blower motor forces the air into the ductwork.
What is the purpose of the thermostat?
Answer:
The thermostat senses and controls the temperature in the
rooms.
10. _____________________ is achieved when the temperature in all
rooms are equal within one degree.
Answer:
Equilibrium
11. Besides protecting from electrical overload, what is another purpose
of fuses and circuit breakers?
Answer:
They stop the electrical current when the maximum
temperature on a device is exceeded, preventing overheating
of the device. This protects the individual components in the
system.
Applied Technology • 117
POSTTEST
12. What is the purpose of vents in a piece of equipment?
Answer:
ventilation, allowing air to move so that heat will not
accumulate
13. What does the fan in a computer do?
Answer:
cools the components
14. A fan moves the air around the room, but it does not actually cool
the air. True or False?
Answer:
true
15. Heat always stays near the floor while cooler air rises to the ceiling.
True or False?
Answer:
false
16. Another word for pneumatic pressure is _______________.
Answer:
air pressure
17. Water or oil pressure is called _________________.
Answer:
hydraulic pressure
18. What benefit does compressed air provide?
Answer:
Compressed air allows a device to apply much more power
to do work.
118 • Applied Technology
POSTTEST
19. A water flow system has ________________________ to control and
direct the flow of water.
Answer:
valves
20. In a home water system, when you open all the faucets, what will
happen?
Answer:
Water pressure will be reduced at all the faucets.
21. Current that flows in only one direction is called:
Answer:
b. direct current
22. The rate at which current flows is called:
Answer:
b. amperage
23. The amount of power derived from an electrical device is:
Answer:
c. wattage
24. Pressure is applied to electrons to force them through a conductive
material. This pressure is measured in:
Answer:
a. volts
Applied Technology • 119
POSTTEST
25. Name at least three simple machines.
Answer:
Any three of the following:
wheel and axle
pulley
gear
inclined plane
lever
26. A ________________ machine is one that is made up of more than
one simple machine.
Answer:
compound or complex
27. Give two examples of a compound or complex machine.
Answers:
Any two of the following:
bicycle
car
typewriter
weight machine
scissors
can opener
treadmill
hand drill
rod and reel
(numerous others)
28. A ______________________ is something that does work.
Answer:
machine
29. A machine that consists of two inclined planes placed back to back
is called a ____________________.
Answer:
wedge
120 • Applied Technology
POSTTEST
30. The center of an axle is called the:
Answer:
c. fulcrum
31. How would you load a truck with the following items: piano, dresser,
four chairs, assorted boxes?
Answer:
Put the piano in the center of the wall nearest the truck cab.
Put the dresser in one of the back corners. Make sure that
the heavier boxes are on the opposite side as the dresser.
Put chairs against the side walls and assorted boxes around
the other furniture.
32. Why would positioning be important in the previous question?
Answer:
The proper balance must be maintained to provide the best
equilibrium possible.
33. ________________ ________________ involves the ability to
manipulate and rotate mentally two- and three-dimensional
objects.
Answer:
Spatial visualization
34. A window blind is an example of:
Answer:
c. pulley
35. A wood screw is an example of:
Answer:
c. inclined plane
Applied Technology • 121
CALCULATING YOUR SCORE
Calculate your score counting the number of questions you answered correctly. If a
problem asked you to list several items or steps and you missed one or more, count the
question as answered incorrectly. Divide the number of your correct answers by 35.
Change the decimal answer to a percentage by moving the decimal two places to the
right.
122 • Applied Technology
SUMMARY
Congratulations!
How well did you do on the Posttest? If you scored
91% or higher, you have a reasonable chance to pass
Level 5 of the ACT WorkKeys® Applied Technology
assessment. Remember to use the IDEAL model when
solving problems.
I
D
=
=
E
A
L
=
=
=
Identify the problem
Define and represent the problem
boundaries
Explore alternative approaches
Act on a plan
Look at the result
Now, don’t be discouraged if you scored below 91%.
Practice the exercises in this course – you can do it.
Your enhanced work skills will pay off in the long run.
Don’t forget to practice your problem-solving skills.
Applied Technology • 123
REFERENCE
EDWIN’S TEST–TAKING TIPS
Preparing for the test . . .
Complete appropriate levels of the WIN Instruction Solution self-study courses. Practice
the exercises until you begin to feel comfortable solving problems.
Get a good night’s rest the night before the test and eat a good breakfast on test day.
Your body (specifically your mind) works better when you take good care of it.
You should take the following items with you when you take the ACT WorkKeys®
Applied Technology assessment: (1) pencils; pens are not allowed to be used on the
test; it is a good idea to have more than one pencil since the test is timed and you do
not want to waste time sharpening a broken pencil lead; and (2) your calculator; be
sure your batteries are strong if you do not have a solar-powered calculator and that
your calculator is working properly. Pencils will be provided for those who need them.
Allow adequate time to arrive at the test site. Being in a rush or arriving late will likely
upset your concentration when you actually take the test.
About the test . . .
The test is comprised of approximately 32 multiple-choice questions. The questions
cover four areas: thermodynamics, fluid dynamics, electricity, and mechanics. Some
questions will be presented as single questions while others may be in groups of two
and refer to specific figures or scenarios. You will not be penalized for wrong answers,
so it is better to guess than leave blanks. You will have 45 minutes to complete the
test.
You will not be allowed to use scratch paper, but there is room in your assessment
booklet to make calculations in solving.
124 • Applied Technology
REFERENCE
During the test . . .
Listen to instructions carefully and read the test booklet directions. Do not hesitate
to ask the administrator questions if you do not understand what to do.
Pace yourself since this is a timed test. The administrator will let you know when you
have 5 minutes left and again when you have 1 minute remaining. Work as quickly as
possible, but be especially careful as you enter numbers into your calculator.
If a problem seems too difficult when you read it, skip over it (temporarily) and move
on to an easier problem. Be sure to put your answers in the right place. Sometimes
skipping problems can cause you to get on the wrong line, so be careful. You might
want to make a mark in the margin of the test, so that you will remember to go back
to any skipped problems.
Since this is a multiple-choice test, you have an advantage answering problems that
are giving you trouble. Try to eliminate any unreasonable answers and make an
educated guess from the answers you have left.
If the administrator indicates you have one minute remaining and you have some
unanswered questions, be sure to fill in an answer for every problem. Your guess is
better than no answer at all!
If you answer all of the test questions before time is called, use the extra time to check
your answers. It is easy to hit the wrong key on a calculator or place an answer on the
wrong line when you are nervous. Look to see that you have not accidentally omitted
any answers.
Applied Technology • 125
REFERENCE
Dealing with test anxiety . . .
Being prepared is one of the best ways to reduce test anxiety. Remember to use the
five steps that we used in solving problems: identify the problem, define the problem,
explore alternatives, act on a plan, and look at the result. Identifying several ways to
solve problems and following a systematic process should increase your confidence
and reduce anxiety.
Do not think negatively about the test. The story about the “little engine that could”
is true. You must, “think you can, think you can, think you can.” If you prepare
yourself by studying problem-solving strategies, there is no reason why you cannot be
successful.
Do not expect yourself to know how to solve every problem. Do not expect to know
immediately how to work the problems when you read them. Everyone has to read
and reread problems when they are solving problems. So, don’t get discouraged; be
persistent.
Prior to the test, close your eyes, take several deep breaths, and think of a relaxing
place or a favorite activity. Visualize this setting for a minute or two before the test is
administered.
During the test if you find yourself tense and unable to think, try the following
relaxation technique:
1.
2.
3.
4.
5.
Put your feet on the floor.
Grab under your chair with your hands. (Hope there are no surprises!)
Push down with your feet and up on your chair at the same time - hold for 5
seconds.
Relax 5 seconds (especially try to relax your neck and shoulders).
Repeat a couple of times as needed, but do not spend the entire 45 minutes of
test trying to relax!
Studying with a partner is another way to overcome test anxiety. Encouragement
from each other helps to increase your confidence.
126 • Applied Technology
REFERENCE
BASIC SCIENTIFIC PRINCIPLES
Applied Technology focuses on:
• Principles related to power sources - for mechanical, electrical, thermal, and fluid
systems
• Principles related to flow - for mechanical, electrical, thermal, and fluid systems
• Principles related to pressure - for mechanical, electrical, thermal, and fluid systems
• Principles related to resistance - for mechanical, electrical, thermal, and fluid systems
The basic scientific principles involved with energy sources, flow, pressure, and resistance
appear below:
Bernoulli’s principle: The faster the flow of air or fluid, the lower the pressure.
Boyle’s law: For a certain amount of gas, at a constant temperature, as the pressure (P)
increases, the volume (V) of the gas decreases so that P times V is constant (k). (PV=k).
Charles’ law: For a certain amount of gas, at a constant pressure, as the absolute
temperature of the gas increases, the volume of the gas also increases. Mathematically
this is: Volume (V) divided by temperature (T) equals a constant (k). V/T=k The
temperature must be on an absolute scale that is in reference to absolute zero.
Hooke’s law: The greater the force exerted on an object, the more it will be moved. For
example, the heavier the weight hanging from a spring, the more the spring will be
stretched.
Newton’s laws of motion
• An object will remain at rest or in uniform motion unless acted upon by an outside
force.
• When a force acts upon an object, it changes the momentum of that object, and
this change is proportional to the applied force and to the time that it acts upon
the object.
• Every action (force) is followed by an equal and opposite reaction (force).
Applied Technology • 127
REFERENCE
Laws of Thermodynamics
• Energy cannot be created or destroyed.
• Heat energy always flows spontaneously from hot to cold.
Ohm’s law: Current is directly proportional to the voltage and inversely proportional to
the resistance.
Pascal’s law: Pressure added to a confined fluid at any point instantly appears equally at
all other points and is always at right angles to the containing surfaces.
Generalizations that can be made about mechanics:
A machine is something that does work.
Work is done when a force causes an object to move.
Simple machines (gears, pulleys, inclined planes, levers, wheel and axle), which are
described below, make up compound (or complex) machines.
Compound machines include a bicycle, a rod and reel, a typewriter, a can opener, scissors,
a hand drill, a car, a weight machine, and a treadmill.
Gears
• The force that is applied to a driver gear is transferred to a driven gear.
• When two gears of different sizes are meshed together, the smaller gear turns
faster (more rotations per minute) than the larger gear.
• Gears that are meshed together move in opposite directions.
• The direction and speed of the driver gear determines the speed and direction of
gears that are meshed with it.
• Common applications of gears include bicycle sprocket chains, speedometers,
clocks, electric mixers, lawn sprinklers, and egg beaters.
128 • Applied Technology
REFERENCE
Pulleys
• A pulley is a wheel with a rope, belt, or chain around it.
• Pulleys change the direction of movement and make work easier.
• Fixed pulleys change the direction that something is moved; they do not make
work easier.
• Movable pulleys change the direction that something is moved and make work
easier.
• The more pulleys in the system, the easier it is to do work (pull or lift an object).
• The more pulleys involved in a system, the greater distance must be pulled, but
the easier it is to do work.
• The thinner the windlass (winch), the easier it is to turn.
• In two different sets of pulleys, if the wheels are connected by a shaft and the two
wheels on one pulley are the same size as the two wheels on the other pulley, they
will both turn at the same speed.
• Common pulley applications include crankshafts, sailboats, boat lifts, window
blinds, cranes, elevators, and escalators.
Inclined Planes
• An inclined plane is a slanted surface that is used to raise or lower heavy objects
from one position to another.
• Inclined planes help reduce the amount of force needed to do a given amount of
work, but require greater distance.
• The steeper the plane, the more difficult the work.
• Wedges are two back-to-back inclined planes.
• Common applications of inclined planes include a screw, a bolt, a drill bit, a
clamp, a car jack, and a screw-on bottle top.
Applied Technology • 129
REFERENCE
Levers
• A lever is a bar or rod that is free to move or turn on a fulcrum.
• A lever multiplies force, but some distance must be given up.
• The shorter the effort arm, the less force is attained and the greater distance is
attained.
• The longer the effort arm, the more force is attained and the less distance is attained.
• Examples of levers include scissors, a broom, a claw hammer, a nutcracker, a mop,
tongs, a crowbar, a can opener, tweezers, a baseball bat, boat oars, and a car jack
handle.
Wheel and Axle
• A wheel and axle is like a spinning lever (an ice cream machine crank).
• The center of the axle is the fulcrum.
• The wheel is larger than the axle; for one rotation, a point on the edge of the
wheel travels a greater distance than a point on the axle. While the work done
by the axle and the wheel are the same, the greater distance traveled of the
point on the edge of the wheel yields a smaller force at the edge of the wheel
versus the edge of the axle.
• Common wheel and axle applications include a screwdriver, roller skates,
a water-faucet handle, a bicycle pedal, a can opener, and a car steering wheel.
130 • Applied Technology
REFERENCE
Overview of Electricity
Electricity is the continuous flow of electrons, or current, from one atom to another. No
electron flow will occur unless there is a pathway over which the electrons can move.
This flow is similar to a water system, where pipes or hoses move water from storage
tanks to where it is needed. In electrical wiring, the pathway through which electrical
current flows is called a circuit. A simple circuit consists of a power source, conductors,
load, and a device for controlling current. Each is described below.
In buildings, the power source could be the electrical generating stations that pump
electricity into residential and commercial buildings. However, other common sources
of electrical power include small generators and batteries.
Conductors, or wiring, provide a path for the current so that it can travel from one point
to another.
A load is a device through which electricity produces work. For example, a lamp is a load
that, when plugged in and turned on, produces light. Other examples of loads include
heaters, electric motors, and televisions.
Switches (on-off switches) control when electrical current flows through circuits. Fuses
and circuit breakers are protective devices that control current by preventing too much
current from flowing in the circuit, which would damage equipment. When an excessive
amount of electricity passes through them, fuses and circuit breakers “blow” to stop the
flow of electricity through the circuit.
In a circuit, resistance lowers the amount of electrical energy available to do work. Both
wires and load affect resistance. It might be helpful to think of a similar situation with a
hose that is connected to two sprinklers. As water passes through a hose, turns or kinks
in the pathway cause friction (which is resistance) that results in a slower flow. In addition,
when some of the water is diverted to the first sprinkler (which is a load), less water is
available for use in the second sprinkler.
Applied Technology • 131
REFERENCE
There are two ways or methods of having current flow. Direct current flows in one
direction. In most cases, direct current is provided to equipment by batteries (flashlights
and portable radios). Alternating current flows in one direction, then reverses to the
other direction. Alternating current is provided to equipment through electrical substations
in buildings. In the United States, common household current reverses itself 60 times
per second. This results in 120v 60 cycle AC. The international reference for cycles is
defined in hertz (one hertz = 1 cycle per second).
Measurement of Electric Current
The rate at which electricity flows is called amperage. It is measured in amperes. A 100watt bulb requires a current of approximately 1 ampere to make it light up completely.
Current flow is measured with an ammeter. Most electrically powered equipment indicate
the amount of current needed to operate it properly.
Measurement of Electrical Pressure
Pressure is applied to electrons to force them to move through a conductor and around a
circuit. This pressure is measured in volts. The pressure, or voltage, is available in wiring
circuits all of the time - whether or not electrical equipment is being used. Voltage is
measured with a voltmeter.
Calculation of Power
The amount of power derived from an electrical device or system is its wattage. In other
words, it is the product obtained from electrical energy; it is the power that we put into
use. For example, the electric company sells electrical energy. Electrical energy or power
is measured in watts and can be calculated as follows:
For direct-current circuits: volts × amperes = watts
For alternating-current circuits: volts × amperes × power factor = watts
NOTE: Power factors range from 0-1. Large equipment (an electric heater) may have a
power factor as high as 1; small equipment (a small motor) may have a power factor as
low as .25.
132 • Applied Technology
REFERENCE
Ohm’s law
Ohm’s law is a simple formula used to describe the relationship between current (flow),
voltage (pressure), and resistance of an electrical circuit. Each component interacts to
affect the operation of a circuit. In other words, because voltage pushes current through
a resistance, a change in any of the components will result in a change in the others. The
following three equations are Ohm’s law rearranged to solve for each of the quantities:
Current = Voltage ÷ Resistance I = E/R
amps = volts ÷ ohms
An increase in voltage causes an increase in
electrical current flow. An increase in circuit
resistance causes a decrease in electrical current
flow.
Voltage = Current × Resistance E = I × R
volts = amps × ohms
An increase in current causes an increase in
voltage. An increase in resistance causes an
increase in voltage.
Resistance = Voltage ÷ Current R = E/I
ohms = volts ÷ amps
Applied Technology • 133
REFERENCE
Generalizations that can be made about electricity:
• The longer the wire, the greater the resistance; the thinner the wire, the greater
the resistance.
• An increase in temperature of a wire causes an increase in resistance.
• An ordinary electrical cord has two wires; one for the flow of current from the
power source and the other for the return or ground.
• The voltage (pressure) and current (flow of electricity) directly affect how much
power is available to do work. Less energy source or lower flow will result in less
electrical power being produced.
• A series circuit has only one path for the flow of current. In a series circuit, objects
are placed one after another and the current flows through each of them in
succession. The current is the same throughout, however, and the voltage is divided
among the objects in the circuit.
• In a parallel circuit, there are 2 or more paths, or branches, for the flow of current.
The current will divide and flow through each of the paths simultaneously. Every
branch has the same voltage and - if the appliances are all the same - will have the
same amount of current. The total circuit resistance is less than any one branch.
• When batteries are connected in a series, the current is the same; the total voltage
is the sum of the voltage of each battery. The terminals are connected +, -, +, -,
and so on.
• When batteries are connected in parallel, the total current is the sum of the currents
in each battery; the total voltage is the same as that of one cell. The terminals are
connected +, +, +, and -, -, -.
134 • Applied Technology
REFERENCE
Generalizations that can be made about heat:
• Heat travels through conductors (metal) better than through insulators (wood).
• Dark-colored surfaces absorb more heat than light-colored surfaces.
• Rough or dull surfaces absorb more heat than smooth or shiny surfaces.
• When friction causes heat, the object that is in constant contact gets hotter than
the movable object. (For example, the wood being cut gets hotter than the saw
blade; car brake shoes get hotter than the wheel).
Generalizations that can be made about fluids:
Pressure
• The amount of pressure exerted by a fluid depends upon the height and the density
of that fluid and is independent of the shape of the container that is holding the
fluid.
• The deeper the fluid, the greater the pressure it exerts.
• The denser the fluid, the greater the pressure it exerts (salt water is denser than
fresh water).
• Fluids seek equilibrium - they seek their own level; a fluid will flow from a place of
high pressure to a place of low pressure.
• A fluid can never rise higher than its source without an external force (a pump).
Applied Technology • 135
REFERENCE
Evaporation
• The higher a liquid’s temperature, the faster it will evaporate.
• The lower a liquid’s pressure, the faster the liquid will evaporate.
• The more area of liquid that is exposed to air, the faster the liquid will evaporate.
• The more circulation of air above a liquid, the faster the liquid will evaporate.
Boiling Point
• Increased pressure on a liquid raises the liquid’s boiling point.
• Decreased pressure on a liquid lowers the liquid’s boiling point.
136 • Applied Technology
REFERENCE
BIBLIOGRAPHY
Adkinson, S., & Fleer, M. (Eds.). (1995). Science with reason. London: Hodder and
Stoughton Educational.
American Association for the Advancement of Science (1993). Benchmarks for science
literacy: A project 2061 report. New York: Oxford University Press.
American Association for the Advancement of Science (1990). Science for all Americans:
A project 2061 report on literacy goals in science, mathematics, and technology. New York:
Oxford University Press.
Bransford, J., & Stein, B. (1984). The IDEAL problem solver: A guide for improving
thinking, learning, and creativity. New York: W. H. Freeman and Co.
Ohio Department of Education (1994). Ohio’s competency-based science model: Scientific
literacy for the 21st century. Columbus, OH: State Board of Education.
National Council of Teachers of Mathematics (1993). Curriculum and evaluation
standards for school mathematics. Reston, VA: NCTM.
National Research Council (1996). National science educational standards. Washington,
DC: National Academy Press.
The Secretary’s Commission on Achieving Necessary Skills (1992). Learning a living:
A blueprint for high performance: A SCANS report for America 2000. Washington, DC:
U.S. Department of Labor.
Applied Technology • 137
ANSWERS TO POP QUIZ QUESTIONS
Page 17 — IDEAL Strategy
• Identify the problem
• Define and represent the problem
• Explore alternatives
• Act on a plan
• Look at the result
Page 36 — As fluid depth increases, the pressure increases accordingly.
Page 64 — A circuit that has more than one path is called a parallel
circuit.
138 • Applied Technology
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