126 UNIT B Structures: Form and Function

5.0 Good design, materials, andconstruction make structures stable and strong.

Inuit people built this inukshuk to help travellers find their way. “Inukshuk” means “something that performs the function of a person.”

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What You Will LearnIn this chapter, you will:

• describe factors that make a structure stable

• describe the centre of gravity of structures

• describe the symmetry of structures

• predict the stability of a structure based on itscentre of gravity

Why This Is ImportantWhen designing a structure, you must considerthe properties of the materials and theconstruction techniques you will use. Both affectthe strength and stability of the final structure.Combined with your understanding of form andfunction from chapter 4, this will help youchoose and build better structures.

Skills You Will UseIn this chapter, you will:

• investigate how structures support loads

• design, build, and test structures

Good design, materials, and construction make structures stable and strong. 127

K-W-L ChartMake a three-column chart with the headings“What I Know,” “What I Wonder,” and “What ILearned.” Think about the chapter title and fillin the first two columns. You will completethe third column at the end of the chapter.

Key Terms• structural components • stability• stress • centre of gravity• fatigue • product recall• failure • prototype• symmetry

Before Reading

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128 UNIT B Structures: Form and Function

5.0 Getting Started

Your classroom contains many different structures (Figure 5.1). Each structure has a form and a function.

If you examine some of the structures, you will notice that thestructures in your classroom are made up of many types ofmaterials.

If you examine each structure even more closely, you willsee that those materials are held together by different types offasteners, such as bolts and welds (Figure 5.2), wire (Figure5.3), and thread and glue (Figure 5.4).

The combinations of materials and fasteners used to build or manufacture structures can affect their stability and strength.Stability is the ability of a structure to maintain or resume itsposition when an external force has been applied to it. Look atseveral different bookcases. You may notice that some of themsag in the middle and others do not. This may be due to thematerial they are made from. A shelf that does not bend may

Figure 5.2 The desk leg is weldedto the horizontal bar, and the lengthof the leg can be adjusted with a bolt.

Figure 5.1 Your classroom has manystructures that are made of differentmaterials and held together bydifferent fasteners.

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have been built using stronger or thicker material. On the other hand, the shelf may be supported with another structuralcomponent, for example, an extra piece of material.

Structures must be strong enough for their intendedfunctions and to be able to withstand theforces that might affect them. Thismight mean adjusting the design,choosing different materials, oraltering construction techniques.Time and effort are needed inorder to design effectivestructures.

In this chapter, you will learnhow structures are designed for strength, stability, function, and form.

129Good design, materials, and construction make structures stable and strong.

B22 Quick Lab

PurposeTo generate a list of as many materials andfasteners as possible in 1 min

Procedure1. Write “Materials” on your sheet of paper.

2. When your teacher gives you the signal, startwriting a list of all of the different types ofmaterials you see around your classroom.Stop when the teacher gives you the signalthat 1 min is up.

3. Turn your paper over and write “Fasteners” onyour sheet of paper.

4. When your teacher gives you the signal, startmaking a list of all of the different types offasteners you see in your classroom. Stopwhen the teacher gives you the signal that 1 min is up.

Questions

5. Look at your list of materials and your list offasteners. How do the lists compare?

6. What do you notice about materials and theireffect on form and/or function?

7. What do you notice about fasteners and theireffect on form and/or function?

8. Choose a structure in your classroom.Imagine that it was made from a differentmaterial and put together with differentfasteners. Would it have the same form orfunction? Would you be able to use it in thesame way you do now?

Materials and Fasteners Hunt

Figure 5.4 Book pages are sewntogether with thread, then glued intothe binding.

Figure 5.3 These beads are strungtogether with wire.

Materials & Equipment■ stopwatch or watch with a second hand

■ paper and pencil

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