100 exam-style questions on Material classification and properties — topic A3.1 of Design in theory in the IB Design Technology syllabus — with answers and explanations. Samples below; the full set is free with an account.
Balsa is classified as a hardwood although it is one of the least dense and softest timbers in general use. Which criterion places it in that class?
Answer: It comes from a broad-leaved, deciduous tree
Timber classification is botanical rather than mechanical: hardwoods come from broad-leaved trees and softwoods from conifers. That is why balsa is a hardwood and pitch pine, which is far harder to dent, is a softwood.
The moulded body of an electrical plug is heated strongly by a fault. It blackens and chars but never softens or flows. Which conclusion about the polymer is correct?
Answer: It is a thermoset, because cross-links prevent the chains from moving
Cross-links are formed permanently while a thermoset cures, so the material degrades before it can melt. Only thermoplastics can be softened and reshaped repeatedly, which is also why only they can be recycled by remoulding.
Which of these metals is classified as ferrous?
Answer: Stainless steel
Ferrous simply means that the metal is based on iron, and adding chromium to make steel corrosion resistant does not change that. Brass and bronze are copper alloys, so both are non-ferrous despite looking metallic and heavy.
A polymer shelf bends visibly as soon as the books are placed on it and springs back to its original shape the moment they are lifted off. Which property of the material is inadequate?
Answer: Stiffness
The deflection appears immediately and disappears on unloading, so it is elastic deformation, and resistance to elastic deformation is stiffness. Nothing has broken and nothing is permanent, so strength, toughness and creep resistance are not what is lacking here.
Glass-reinforced polyester consists of glass fibres embedded in a cured resin. How should this material be classified?
Answer: A composite, because a reinforcement is bound within a matrix
A composite keeps two distinct phases, matrix and reinforcement, which remain identifiable in the finished material. An alloy, by contrast, is a mixture of metals at atomic level with no separate phase to see.
Which of these is a physical property rather than a mechanical property of a material?
Answer: Thermal conductivity
Physical properties such as density, melting point and thermal or electrical conductivity are measured without applying a load. Mechanical properties describe how the material responds once a force is applied to it.
That was 6 of 100 Material classification and properties questions.
Practise all 100 freeDistinguishAO2 · 1–3 marks
Make the difference clear for BOTH terms — a definition of one of them is only half an answer.
OutlineAO2 · 1–3 marks
A brief account or summary: the main points in two or three sentences, no evaluation.
DrawAO1 · 1 marks
A labelled, accurate drawing with a ruler where lines are straight; axes and units on a graph.
100 Material classification and properties questions — free with an account. Spaced repetition, streaks and full exam simulations included.
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