What physical and working properties make a material right for a job?
The physical and mechanical properties of materials, including strength, hardness, toughness, ductility, malleability, elasticity, density and conductivity, and how they guide material selection.
A focused answer to the WJEC GCSE Design and Technology content on material properties, covering physical properties such as density and conductivity and mechanical working properties such as strength, hardness, toughness, ductility, malleability and elasticity, and how they guide material choice.
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What this topic is asking
Before you can choose a material, you need the vocabulary to describe what it does. WJEC expects you to know the main physical and mechanical (working) properties, define them, and use them to justify a material choice. This underpins every materials topic in Unit 1 across all three routes, because every selection question is really a question about properties.
Physical properties
Mechanical (working) properties
Strength is not the same as toughness or hardness
Using properties to select a material
When you justify a material, name the property the product needs and link it to how the product is used. A bridge cable needs high tensile strength and ductility; a saucepan body needs good thermal conductivity but an insulating handle; a bicycle frame needs strength with low density; a drinks can needs malleability and corrosion resistance.
Try this
Q1. Define toughness and give a product that needs it. [2 marks]
- Cue. Resists sudden impact without shattering; a phone case or a hammer head.
Q2. State one physical property a saucepan body needs and why. [2 marks]
- Cue. Good thermal conductivity, so heat passes quickly to the food.
Exam-style practice questions
Practice questions written in the style of WJEC exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
WJEC-style4 marksExplain why each property is important when choosing a material for a hammer head and for a child's drinking cup.Show worked answer →
A four mark application question linking properties to products. Hammer head: it needs to be hard to resist denting when struck and tough so it does not shatter under shock, which is why a hardened steel is used (2 marks for property plus reason). Child's cup: it needs to be tough so it survives being dropped and have low density so it is light to hold, which is why a polymer such as polypropylene is used (2 marks). Markers reward naming a relevant property and linking it directly to how the product is used. A common error is to name a property without saying why the product needs it.
WJEC-style2 marksState the difference between a material that is ductile and one that is malleable.Show worked answer →
A two mark Define-and-distinguish question. A ductile material can be drawn out into a wire without breaking, such as copper drawn into electrical cable (1 mark). A malleable material can be hammered or pressed into thin sheets or new shapes without cracking, such as aluminium pressed into a drinks can (1 mark). Markers reward the wire-versus-sheet distinction. A common error is to treat the two terms as the same; both involve permanent shaping but in different ways.
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