Choosing Materials

Define in your own words and give an example of each of these material properties: hardness, electrical conductivity, and density.

Match each object with the property of the material that makes it possible: (a) a window, (b) a copper wire, (c) a hammer, (d) a raincoat. Properties: conductivity, hardness, waterproofing, and transparency. Justify each pair in one sentence.

Explain the difference between a mechanical property (such as hardness or elasticity) and a thermal or electrical property (such as conductivity), with an example of each type.

What property makes cork a good bottle stopper and rubber a good material for tyres? Name the property in each case and explain it in one sentence.

To build a garden bench that will always be outdoors, compare wood and steel across at least three relevant properties and decide which you would choose, justifying your decision.

The handles of pots and frying pans are made of plastic or wood, never the same metal as the body. Explain this design decision using at least two material properties.

The handle of a screwdriver combines hard plastic with rubberised areas. Explain what properties each material provides and why the handle is not made entirely of steel like the shaft.

Explain what a composite material is using the example of reinforced concrete or fibreglass: what each component provides and why the combination improves upon the materials separately.

A team chooses aluminium for an outdoor structure 'because it does not rust'. Qualify this statement: what actually happens to aluminium when exposed to air and why that ultimately protects it.

A material must be chosen for a reusable bottle for a school bag. Evaluate stainless steel, plastic, and glass based on weight, impact resistance, hygiene, and cost; choose one and justify your decision, acknowledging which disadvantages you accept.

The plastic hinges on a locker break after a few months of use. Analyse which property was ignored when choosing that material, what alternative material you would propose, and why.

A yoghurt pot combines several materials (plastic pot, aluminium lid, label). Analyse why the use of multiple materials complicates its recycling and propose a redesign that avoids it.