An engineer is choosing a material to make the frame of a bicycle.
The table shows some properties of six materials.
| Material | Density (g/cm3\mathrm{g/cm^{3}}g/cm3) | Tensile strength (MPa) | Relative cost per kg | Other information |
|---|---|---|---|---|
| aluminium alloy | 2.7 | 300 | 3 | does not corrode easily; dents but does not shatter |
| carbon-fibre reinforced polymer | 1.6 | 1500 | 40 | very stiff; can crack if hit hard |
| glass | 2.5 | 50 | 2 | brittle; shatters |
| poly(propene) | 0.90 | 35 | 1.5 | flexible; bends easily |
| steel | 7.8 | 500 | 1 | rusts unless it is protected |
| titanium alloy | 4.5 | 900 | 25 | does not corrode |
Name the material in the table that is a composite.
Describe what is meant by a composite material.
Engineers compare materials using their specific strength.
specific strength = tensile strength ÷ density
The specific strength of steel is 64.
Calculate the specific strength of the titanium alloy and of the aluminium alloy.
Give your answers to 3 significant figures.
Titanium alloy = ...... Aluminium alloy = ......
A company makes low-cost bicycles for children. The frame must be cheap and light, and it must not rust or corrode.
Suggest and explain which material the company should use for the frame. Use data from the table and your answer to (b).
Explain why glass and poly(propene) are not suitable for a bicycle frame.
Steel is an alloy of iron with a small amount of carbon.
Explain why steel is used for bicycle frames rather than pure iron.
61 exam-style questions on OCR GCSE Chemistry 6.1 Improving processes and products, covering 6.1.1 Extracting metals industrially and by electrolysis, 6.1.2 Life cycle assessment and recycling, 6.1.3 Biological methods of metal extraction, 6.1.4 The Haber process and the production of fertilisers, 6.1.5 Alloys and their uses, 6.1.6 Corrosion and its prevention, 6.1.7 Comparing and selecting materials, and 6.1.8 Industrial conditions, rate and position of equilibrium. Each one has a worked solution and a mark scheme showing where the marks go.