A bicycle company is choosing a material for the frames of its bicycles.
The table shows information about four materials.
| Material | Density / g cm−3\mathrm{g\,cm^{-3}}gcm−3 | Strength / MPa | Relative cost |
|---|---|---|---|
| steel | 7.8 | 400 | 1 |
| aluminium alloy | 2.7 | 300 | 3 |
| carbon-fibre composite | 1.6 | 600 | 25 |
| wood | 0.6 | 80 | 2 |
Carbon-fibre composite is made from carbon fibres held together in a polymer resin. State what is meant by a composite material.
Calculate the strength-to-density value for carbon-fibre composite. Use the equation: strength-to-density value=strengthdensity\displaystyle \text{strength-to-density value} = \frac{\text{strength}}{\text{density}}strength-to-density value=densitystrength
The strength-to-density value for steel is 51. Suggest why frames for racing bicycles are made from carbon-fibre composite.
Suggest why most everyday bicycles are made from steel or aluminium alloy rather than carbon-fibre composite.
Reinforced concrete is another composite material. It is made of steel rods inside concrete. Concrete is strong when squashed but cracks easily when stretched or bent. Explain why steel rods are added to concrete used for bridges.
36 exam-style questions on Edexcel GCSE Chemistry 10.5 Bulk and surface properties of matter including nanoparticles, covering 10.5.1 Nanoparticles: size, uses and risks and 10.5.2 Comparing and selecting materials. Each one has a worked solution and a mark scheme showing where the marks go.