Textbook: Properties of Materials | Technical Science for Grade 10 PDF Download

 Page 1


 technical science GRADE 10 199
 c hapter 8 Properties of materials
In engineering and technology you are going to work with many different materials. You need 
two kinds of knowledge about materials.
First, you have to know the properties of materials; that is to say, how you can choose them 
and use them, how you can change them, and how you can combine them. 
Second, you have to know the reasons why materials have their properties. That is to say, you 
have to understand how their atoms behave.
The fi rst kind of knowledge is about material on the macro-scale. “Macro” means big; you are 
going to study pieces of material that are big enough to hold in your hand or in a cup.
The second kind of knowledge is about the same materials but on the nano-scale. “Nano-
scale” knowledge is knowledge about the atoms that make up materials. Atoms and most 
molecules are too small to see, even with a microscope. So we have to use a clever model that 
lets us work out how the particles behave – this model is called the Particle Kinetic Model of 
Matter (the PKMM).
Now here is a map to show where we are going in the next four chapters. 
…but here we 
answer them!
In chapter 8 we study 
materials on the macro-
scale. We study, for 
example, strength, density, 
magnetic properties, 
melting and boiling.
In chapter 9 we study 
materials on the nano-
scale; that is, the atoms 
and molecules that 
make up the materials 
and use the PKMM.
chapter 10 uses the 
PKMM to understand how 
elements and compounds 
react and how ions form.
chapter 8 leaves some 
questions unanswered about 
the properties of materials… 
what are the reasons why these 
materials have these properties?
In chapter 11 we use the PKMM to 
answer the questions about:
 ? why some materials are magnetic
 ? how some materials conduct heat 
and electricity
 ? why boiling points depend on altitude
TechSci_G10-LB-Eng-DBE3_9781431522842.indb   199 2015/12/17   10:03 AM
Page 2


 technical science GRADE 10 199
 c hapter 8 Properties of materials
In engineering and technology you are going to work with many different materials. You need 
two kinds of knowledge about materials.
First, you have to know the properties of materials; that is to say, how you can choose them 
and use them, how you can change them, and how you can combine them. 
Second, you have to know the reasons why materials have their properties. That is to say, you 
have to understand how their atoms behave.
The fi rst kind of knowledge is about material on the macro-scale. “Macro” means big; you are 
going to study pieces of material that are big enough to hold in your hand or in a cup.
The second kind of knowledge is about the same materials but on the nano-scale. “Nano-
scale” knowledge is knowledge about the atoms that make up materials. Atoms and most 
molecules are too small to see, even with a microscope. So we have to use a clever model that 
lets us work out how the particles behave – this model is called the Particle Kinetic Model of 
Matter (the PKMM).
Now here is a map to show where we are going in the next four chapters. 
…but here we 
answer them!
In chapter 8 we study 
materials on the macro-
scale. We study, for 
example, strength, density, 
magnetic properties, 
melting and boiling.
In chapter 9 we study 
materials on the nano-
scale; that is, the atoms 
and molecules that 
make up the materials 
and use the PKMM.
chapter 10 uses the 
PKMM to understand how 
elements and compounds 
react and how ions form.
chapter 8 leaves some 
questions unanswered about 
the properties of materials… 
what are the reasons why these 
materials have these properties?
In chapter 11 we use the PKMM to 
answer the questions about:
 ? why some materials are magnetic
 ? how some materials conduct heat 
and electricity
 ? why boiling points depend on altitude
TechSci_G10-LB-Eng-DBE3_9781431522842.indb   199 2015/12/17   10:03 AM
200 chapter 8 PROPERTIES OF MATERIALS
unit 8.1 Strength of materials
Materials are the substances we choose for making things
Look at Figure 8.1. When you design something, you 
want to know about the properties of the materials 
you are going to use. For example, will the material 
be strong enough for the forces that will act on it? 
Will the material be a good heat insulator? Will the 
material break and shatter if you drop it? Will the 
materials be able to bend without breaking? What 
will happen to the material if it gets very hot? And if it 
gets very cold?
Strength, toughness, fl exibility, insulation – 
these are physical properties of materials. 
There are some special words that we use for 
properties of materials: 
Brittle means a material can be hard and strong, but it will break easily if it is hit or if you drop 
it on a hard surface. For example, glass is hard but brittle. A steel fi le is brittle and may crack if 
you drop it on the fl oor. On the other hand, some materials are not brittle at all: they are tough . 
For example, polyethylene tubing that is used for water-pipes is tough. You can hit it and bend it 
and it will not break.
Malleable means you can shape the material by hammering or pressing it, and it will not 
break. For example, sheet metal can be pressed into the shape of car body panels. 
Ductile means that you can stretch the material into a wire. For example, copper and low-
carbon steel are the materials from which wire is made. Aluminium strips that you see in 
window-frames are extruded from aluminium rods. To extrude means to squeeze the material 
through a die that gives it the shape you want. 
how strong is a piece of material?
“Strong” has many meanings when we talk about materials. As you learned in Chapter 3, the 
strength of a piece of material is its ability to resist forces of compression, torsion, bending, 
shear and tension. Tension means stretching forces, and we are going to investigate strength in 
tension.
Engineering laboratories test the tensile strength of materials 
by slowly stretching a piece of the material, called a test 
specimen*, in a big machine.
Figure 8.1 Is it strong enough?
? ? specimen – a sample; a small 
piece of the material that is like all 
the rest of the material
TechSci_G10-LB-Eng-DBE3_9781431522842.indb   200 2015/12/17   10:03 AM
Page 3


 technical science GRADE 10 199
 c hapter 8 Properties of materials
In engineering and technology you are going to work with many different materials. You need 
two kinds of knowledge about materials.
First, you have to know the properties of materials; that is to say, how you can choose them 
and use them, how you can change them, and how you can combine them. 
Second, you have to know the reasons why materials have their properties. That is to say, you 
have to understand how their atoms behave.
The fi rst kind of knowledge is about material on the macro-scale. “Macro” means big; you are 
going to study pieces of material that are big enough to hold in your hand or in a cup.
The second kind of knowledge is about the same materials but on the nano-scale. “Nano-
scale” knowledge is knowledge about the atoms that make up materials. Atoms and most 
molecules are too small to see, even with a microscope. So we have to use a clever model that 
lets us work out how the particles behave – this model is called the Particle Kinetic Model of 
Matter (the PKMM).
Now here is a map to show where we are going in the next four chapters. 
…but here we 
answer them!
In chapter 8 we study 
materials on the macro-
scale. We study, for 
example, strength, density, 
magnetic properties, 
melting and boiling.
In chapter 9 we study 
materials on the nano-
scale; that is, the atoms 
and molecules that 
make up the materials 
and use the PKMM.
chapter 10 uses the 
PKMM to understand how 
elements and compounds 
react and how ions form.
chapter 8 leaves some 
questions unanswered about 
the properties of materials… 
what are the reasons why these 
materials have these properties?
In chapter 11 we use the PKMM to 
answer the questions about:
 ? why some materials are magnetic
 ? how some materials conduct heat 
and electricity
 ? why boiling points depend on altitude
TechSci_G10-LB-Eng-DBE3_9781431522842.indb   199 2015/12/17   10:03 AM
200 chapter 8 PROPERTIES OF MATERIALS
unit 8.1 Strength of materials
Materials are the substances we choose for making things
Look at Figure 8.1. When you design something, you 
want to know about the properties of the materials 
you are going to use. For example, will the material 
be strong enough for the forces that will act on it? 
Will the material be a good heat insulator? Will the 
material break and shatter if you drop it? Will the 
materials be able to bend without breaking? What 
will happen to the material if it gets very hot? And if it 
gets very cold?
Strength, toughness, fl exibility, insulation – 
these are physical properties of materials. 
There are some special words that we use for 
properties of materials: 
Brittle means a material can be hard and strong, but it will break easily if it is hit or if you drop 
it on a hard surface. For example, glass is hard but brittle. A steel fi le is brittle and may crack if 
you drop it on the fl oor. On the other hand, some materials are not brittle at all: they are tough . 
For example, polyethylene tubing that is used for water-pipes is tough. You can hit it and bend it 
and it will not break.
Malleable means you can shape the material by hammering or pressing it, and it will not 
break. For example, sheet metal can be pressed into the shape of car body panels. 
Ductile means that you can stretch the material into a wire. For example, copper and low-
carbon steel are the materials from which wire is made. Aluminium strips that you see in 
window-frames are extruded from aluminium rods. To extrude means to squeeze the material 
through a die that gives it the shape you want. 
how strong is a piece of material?
“Strong” has many meanings when we talk about materials. As you learned in Chapter 3, the 
strength of a piece of material is its ability to resist forces of compression, torsion, bending, 
shear and tension. Tension means stretching forces, and we are going to investigate strength in 
tension.
Engineering laboratories test the tensile strength of materials 
by slowly stretching a piece of the material, called a test 
specimen*, in a big machine.
Figure 8.1 Is it strong enough?
? ? specimen – a sample; a small 
piece of the material that is like all 
the rest of the material
TechSci_G10-LB-Eng-DBE3_9781431522842.indb   200 2015/12/17   10:03 AM
 technical science GRADE 10 201
Figure 8.2 shows you the machine that stretches the 
specimens. The jaws of the machine clamp the test 
specimen tightly and then they slowly move apart, 
stretching it. A force gauge* measures the stretching 
force on the specimen and distance gauges measure the 
length of the stretching.
In Figure 8.3 you see that, as the force increased, the 
specimen formed a neck at one point, the neck grew 
narrower, and then it fractured (broke) at that point. 
Figure 8.3 This is a test specimen of steel. The bottom specimen 
is the specimen before the stretching test, and the top one is the 
specimen after the test. The narrow part is called a “neck”, and 
that is where the steel broke. Notice the gauge marks on the 
specimen that show how much it stretched. 
Photo by Rainer Schwab, University of Applied Sciences Karlsruhe, Germany, 201 3. 
This photo is part of a video on a tensile strength test: 
https://www.youtube.com/watch?v=D8U4G5kcpcM
The video can help you to understand a tensile strength test better.  
The video gives more detailed and advanced explanations and formulae than you 
need to know in this grade – you do not need to learn or understand all of that now.
The technologist plots a graph of the measurements on the test specimen; the graph compares 
the amount of stretch (this is called the strain) to the force on the specimen, per unit area of the 
cross-section (called the stress).
From such a graph, a trained person can tell you how this material will behave when forces act 
on it. The graph in Figure 8.4 on the next page tells a story – let’s follow the story.
Figure 8.2 A machine that tests 
specimens of materials for tensile 
strength: the specimen gets clamped 
between the two sets of jaws.
TechSci_G10-LB-Eng-DBE3_9781431522842.indb   201 2015/12/17   10:03 AM
Page 4


 technical science GRADE 10 199
 c hapter 8 Properties of materials
In engineering and technology you are going to work with many different materials. You need 
two kinds of knowledge about materials.
First, you have to know the properties of materials; that is to say, how you can choose them 
and use them, how you can change them, and how you can combine them. 
Second, you have to know the reasons why materials have their properties. That is to say, you 
have to understand how their atoms behave.
The fi rst kind of knowledge is about material on the macro-scale. “Macro” means big; you are 
going to study pieces of material that are big enough to hold in your hand or in a cup.
The second kind of knowledge is about the same materials but on the nano-scale. “Nano-
scale” knowledge is knowledge about the atoms that make up materials. Atoms and most 
molecules are too small to see, even with a microscope. So we have to use a clever model that 
lets us work out how the particles behave – this model is called the Particle Kinetic Model of 
Matter (the PKMM).
Now here is a map to show where we are going in the next four chapters. 
…but here we 
answer them!
In chapter 8 we study 
materials on the macro-
scale. We study, for 
example, strength, density, 
magnetic properties, 
melting and boiling.
In chapter 9 we study 
materials on the nano-
scale; that is, the atoms 
and molecules that 
make up the materials 
and use the PKMM.
chapter 10 uses the 
PKMM to understand how 
elements and compounds 
react and how ions form.
chapter 8 leaves some 
questions unanswered about 
the properties of materials… 
what are the reasons why these 
materials have these properties?
In chapter 11 we use the PKMM to 
answer the questions about:
 ? why some materials are magnetic
 ? how some materials conduct heat 
and electricity
 ? why boiling points depend on altitude
TechSci_G10-LB-Eng-DBE3_9781431522842.indb   199 2015/12/17   10:03 AM
200 chapter 8 PROPERTIES OF MATERIALS
unit 8.1 Strength of materials
Materials are the substances we choose for making things
Look at Figure 8.1. When you design something, you 
want to know about the properties of the materials 
you are going to use. For example, will the material 
be strong enough for the forces that will act on it? 
Will the material be a good heat insulator? Will the 
material break and shatter if you drop it? Will the 
materials be able to bend without breaking? What 
will happen to the material if it gets very hot? And if it 
gets very cold?
Strength, toughness, fl exibility, insulation – 
these are physical properties of materials. 
There are some special words that we use for 
properties of materials: 
Brittle means a material can be hard and strong, but it will break easily if it is hit or if you drop 
it on a hard surface. For example, glass is hard but brittle. A steel fi le is brittle and may crack if 
you drop it on the fl oor. On the other hand, some materials are not brittle at all: they are tough . 
For example, polyethylene tubing that is used for water-pipes is tough. You can hit it and bend it 
and it will not break.
Malleable means you can shape the material by hammering or pressing it, and it will not 
break. For example, sheet metal can be pressed into the shape of car body panels. 
Ductile means that you can stretch the material into a wire. For example, copper and low-
carbon steel are the materials from which wire is made. Aluminium strips that you see in 
window-frames are extruded from aluminium rods. To extrude means to squeeze the material 
through a die that gives it the shape you want. 
how strong is a piece of material?
“Strong” has many meanings when we talk about materials. As you learned in Chapter 3, the 
strength of a piece of material is its ability to resist forces of compression, torsion, bending, 
shear and tension. Tension means stretching forces, and we are going to investigate strength in 
tension.
Engineering laboratories test the tensile strength of materials 
by slowly stretching a piece of the material, called a test 
specimen*, in a big machine.
Figure 8.1 Is it strong enough?
? ? specimen – a sample; a small 
piece of the material that is like all 
the rest of the material
TechSci_G10-LB-Eng-DBE3_9781431522842.indb   200 2015/12/17   10:03 AM
 technical science GRADE 10 201
Figure 8.2 shows you the machine that stretches the 
specimens. The jaws of the machine clamp the test 
specimen tightly and then they slowly move apart, 
stretching it. A force gauge* measures the stretching 
force on the specimen and distance gauges measure the 
length of the stretching.
In Figure 8.3 you see that, as the force increased, the 
specimen formed a neck at one point, the neck grew 
narrower, and then it fractured (broke) at that point. 
Figure 8.3 This is a test specimen of steel. The bottom specimen 
is the specimen before the stretching test, and the top one is the 
specimen after the test. The narrow part is called a “neck”, and 
that is where the steel broke. Notice the gauge marks on the 
specimen that show how much it stretched. 
Photo by Rainer Schwab, University of Applied Sciences Karlsruhe, Germany, 201 3. 
This photo is part of a video on a tensile strength test: 
https://www.youtube.com/watch?v=D8U4G5kcpcM
The video can help you to understand a tensile strength test better.  
The video gives more detailed and advanced explanations and formulae than you 
need to know in this grade – you do not need to learn or understand all of that now.
The technologist plots a graph of the measurements on the test specimen; the graph compares 
the amount of stretch (this is called the strain) to the force on the specimen, per unit area of the 
cross-section (called the stress).
From such a graph, a trained person can tell you how this material will behave when forces act 
on it. The graph in Figure 8.4 on the next page tells a story – let’s follow the story.
Figure 8.2 A machine that tests 
specimens of materials for tensile 
strength: the specimen gets clamped 
between the two sets of jaws.
TechSci_G10-LB-Eng-DBE3_9781431522842.indb   201 2015/12/17   10:03 AM
202 chapter 8 PROPERTIES OF MATERIALS
At point ? there is no stretching force on the steel specimen and so it does not stretch – 
F is zero and the stretch is zero.
Now the force F increases to F
1
 and the steel has stretched a little, from L
0
 to L
1
. We are at 
point ? on the graph. At this point, you could let the steel go, and it would jump back to 
its original length, like a very strong rubber band. 
We say that the part of the graph between ? and ? shows that this type of steel is elastic, 
up to force F
1
.
Engineers draw the 
graph differently. Look 
at the stress-strain graph 
in the challenges and 
projects section at the 
end of this chapter.
Stretching force (in kilonewtons)
Amount of stretching (in mm)
L
1
L
0
F
1
F
2
F
0
1
2
3
0
Figure 8.4 A graph of the stretching that is caused by the force
But if you continue to increase the stretching force from F
1
 to F
2
 (fi nd F
2
 on the graph) the steel 
begins to deform – it gets narrower and longer, and it carries on stretching. 
Now you don’t increase the force; you just keep holding the stretched steel with F
2
 kilonewtons. 
We are at point F
2
 on the graph. The steel keeps on stretching as its atoms begin to slide past 
each other.
Quick activity:
How does the graph show you that the steel goes on stretching?
If you did not pull harder than F
2
 , the steel would not break. 
A force just less than F
2
 is the maximum tensile strength 
of this kind of steel. 
Then at point ? the steel fails, because the atoms of steel are 
sliding apart and can no longer hold together. It snaps with a 
loud bang and you see in Figure 8.3 what the specimen looks like now.
The fact that the steel began to change shape between points ? and ? on the graph tells us 
that the steel is ductile* – that is, it can change shape without breaking. 
? ? ductile (adj.) – a ductile 
metal can be stretched out into 
a thin wire. You could not do 
this with a cylinder of concrete, 
because concrete is not ductile.
TechSci_G10-LB-Eng-DBE3_9781431522842.indb   202 2015/12/17   10:03 AM
Page 5


 technical science GRADE 10 199
 c hapter 8 Properties of materials
In engineering and technology you are going to work with many different materials. You need 
two kinds of knowledge about materials.
First, you have to know the properties of materials; that is to say, how you can choose them 
and use them, how you can change them, and how you can combine them. 
Second, you have to know the reasons why materials have their properties. That is to say, you 
have to understand how their atoms behave.
The fi rst kind of knowledge is about material on the macro-scale. “Macro” means big; you are 
going to study pieces of material that are big enough to hold in your hand or in a cup.
The second kind of knowledge is about the same materials but on the nano-scale. “Nano-
scale” knowledge is knowledge about the atoms that make up materials. Atoms and most 
molecules are too small to see, even with a microscope. So we have to use a clever model that 
lets us work out how the particles behave – this model is called the Particle Kinetic Model of 
Matter (the PKMM).
Now here is a map to show where we are going in the next four chapters. 
…but here we 
answer them!
In chapter 8 we study 
materials on the macro-
scale. We study, for 
example, strength, density, 
magnetic properties, 
melting and boiling.
In chapter 9 we study 
materials on the nano-
scale; that is, the atoms 
and molecules that 
make up the materials 
and use the PKMM.
chapter 10 uses the 
PKMM to understand how 
elements and compounds 
react and how ions form.
chapter 8 leaves some 
questions unanswered about 
the properties of materials… 
what are the reasons why these 
materials have these properties?
In chapter 11 we use the PKMM to 
answer the questions about:
 ? why some materials are magnetic
 ? how some materials conduct heat 
and electricity
 ? why boiling points depend on altitude
TechSci_G10-LB-Eng-DBE3_9781431522842.indb   199 2015/12/17   10:03 AM
200 chapter 8 PROPERTIES OF MATERIALS
unit 8.1 Strength of materials
Materials are the substances we choose for making things
Look at Figure 8.1. When you design something, you 
want to know about the properties of the materials 
you are going to use. For example, will the material 
be strong enough for the forces that will act on it? 
Will the material be a good heat insulator? Will the 
material break and shatter if you drop it? Will the 
materials be able to bend without breaking? What 
will happen to the material if it gets very hot? And if it 
gets very cold?
Strength, toughness, fl exibility, insulation – 
these are physical properties of materials. 
There are some special words that we use for 
properties of materials: 
Brittle means a material can be hard and strong, but it will break easily if it is hit or if you drop 
it on a hard surface. For example, glass is hard but brittle. A steel fi le is brittle and may crack if 
you drop it on the fl oor. On the other hand, some materials are not brittle at all: they are tough . 
For example, polyethylene tubing that is used for water-pipes is tough. You can hit it and bend it 
and it will not break.
Malleable means you can shape the material by hammering or pressing it, and it will not 
break. For example, sheet metal can be pressed into the shape of car body panels. 
Ductile means that you can stretch the material into a wire. For example, copper and low-
carbon steel are the materials from which wire is made. Aluminium strips that you see in 
window-frames are extruded from aluminium rods. To extrude means to squeeze the material 
through a die that gives it the shape you want. 
how strong is a piece of material?
“Strong” has many meanings when we talk about materials. As you learned in Chapter 3, the 
strength of a piece of material is its ability to resist forces of compression, torsion, bending, 
shear and tension. Tension means stretching forces, and we are going to investigate strength in 
tension.
Engineering laboratories test the tensile strength of materials 
by slowly stretching a piece of the material, called a test 
specimen*, in a big machine.
Figure 8.1 Is it strong enough?
? ? specimen – a sample; a small 
piece of the material that is like all 
the rest of the material
TechSci_G10-LB-Eng-DBE3_9781431522842.indb   200 2015/12/17   10:03 AM
 technical science GRADE 10 201
Figure 8.2 shows you the machine that stretches the 
specimens. The jaws of the machine clamp the test 
specimen tightly and then they slowly move apart, 
stretching it. A force gauge* measures the stretching 
force on the specimen and distance gauges measure the 
length of the stretching.
In Figure 8.3 you see that, as the force increased, the 
specimen formed a neck at one point, the neck grew 
narrower, and then it fractured (broke) at that point. 
Figure 8.3 This is a test specimen of steel. The bottom specimen 
is the specimen before the stretching test, and the top one is the 
specimen after the test. The narrow part is called a “neck”, and 
that is where the steel broke. Notice the gauge marks on the 
specimen that show how much it stretched. 
Photo by Rainer Schwab, University of Applied Sciences Karlsruhe, Germany, 201 3. 
This photo is part of a video on a tensile strength test: 
https://www.youtube.com/watch?v=D8U4G5kcpcM
The video can help you to understand a tensile strength test better.  
The video gives more detailed and advanced explanations and formulae than you 
need to know in this grade – you do not need to learn or understand all of that now.
The technologist plots a graph of the measurements on the test specimen; the graph compares 
the amount of stretch (this is called the strain) to the force on the specimen, per unit area of the 
cross-section (called the stress).
From such a graph, a trained person can tell you how this material will behave when forces act 
on it. The graph in Figure 8.4 on the next page tells a story – let’s follow the story.
Figure 8.2 A machine that tests 
specimens of materials for tensile 
strength: the specimen gets clamped 
between the two sets of jaws.
TechSci_G10-LB-Eng-DBE3_9781431522842.indb   201 2015/12/17   10:03 AM
202 chapter 8 PROPERTIES OF MATERIALS
At point ? there is no stretching force on the steel specimen and so it does not stretch – 
F is zero and the stretch is zero.
Now the force F increases to F
1
 and the steel has stretched a little, from L
0
 to L
1
. We are at 
point ? on the graph. At this point, you could let the steel go, and it would jump back to 
its original length, like a very strong rubber band. 
We say that the part of the graph between ? and ? shows that this type of steel is elastic, 
up to force F
1
.
Engineers draw the 
graph differently. Look 
at the stress-strain graph 
in the challenges and 
projects section at the 
end of this chapter.
Stretching force (in kilonewtons)
Amount of stretching (in mm)
L
1
L
0
F
1
F
2
F
0
1
2
3
0
Figure 8.4 A graph of the stretching that is caused by the force
But if you continue to increase the stretching force from F
1
 to F
2
 (fi nd F
2
 on the graph) the steel 
begins to deform – it gets narrower and longer, and it carries on stretching. 
Now you don’t increase the force; you just keep holding the stretched steel with F
2
 kilonewtons. 
We are at point F
2
 on the graph. The steel keeps on stretching as its atoms begin to slide past 
each other.
Quick activity:
How does the graph show you that the steel goes on stretching?
If you did not pull harder than F
2
 , the steel would not break. 
A force just less than F
2
 is the maximum tensile strength 
of this kind of steel. 
Then at point ? the steel fails, because the atoms of steel are 
sliding apart and can no longer hold together. It snaps with a 
loud bang and you see in Figure 8.3 what the specimen looks like now.
The fact that the steel began to change shape between points ? and ? on the graph tells us 
that the steel is ductile* – that is, it can change shape without breaking. 
? ? ductile (adj.) – a ductile 
metal can be stretched out into 
a thin wire. You could not do 
this with a cylinder of concrete, 
because concrete is not ductile.
TechSci_G10-LB-Eng-DBE3_9781431522842.indb   202 2015/12/17   10:03 AM
 technical science GRADE 10 203
activity 1 a tensile strength test of two materials 
In this activity, you are going to model the kind of tensile 
strength test that is done in mechanical and civil engineering 
laboratories. Materials that technologists test include metals, 
plastics, wood, composites like kevlar and fibre-glass.
Look carefully at the test rig set-up in Figure 8.8 on the next 
page. That is what you are going to make. 
First, prepare the test specimens
A. From each of the paper and the plastic material, cut a 
strip about 30 cm long and 1 cm wide. Try to cut very 
straight strips, exactly 1 cm wide.
 The edges of the strips must not have any tears or 
crooked cuts. 
B. Choose one end of a strip to be the bottom, and lay it on 
parcel tape as you see in Figure 8.5. Put the pencil on the 
end of the plastic strip and bring the tape over and stick it 
down. Now your sample will look like Figure 8.6.
Figure 8.5 Put the end of the specimen on the tape, 
and then put the dowel on top of the specimen.
Figure 8.6 Fold the tape over and stick it down. 
This gives you a strong part to hang the bucket on.
specimen
package
tape
pencil
specimen
Now you have to make some gauge marks  
to see where the specimen stretches the most. 
C. Make a mark near the top of each specimen 
and then make 15 marks equal distances apart. 
To write on plastic, use a felt-tip pen.
apparatus (per group)
 ? a small desk to act as a test 
rig. The desk must have 
broad rounded edges, not 
sharp edges.
 ? plastic sheet; the kind used 
for shopping bags
 ? copier paper or exercise 
book paper
 ? scissors for cutting the 
specimens
 ? packaging tape
 ? 2 nails or pencils
 ? string
 ? 2-litre milk bottle with a large 
opening cut near the top
 ? water; at least 2 litres
 ? a beaker to measure 100 ml
top end of specimen
mark with felt-tip pen
Figure 8.7 Make 1 5 gauge marks on the test 
specimen at equal distances.
TechSci_G10-LB-Eng-DBE3_9781431522842.indb   203 2015/12/17   10:03 AM