We can classify materials according to their [?]. However, within each [?] of material the properties can vary widely. The properties can also change with [?] as the weather changes.

Metals, such as Iron and steel, are strong in [?] and compression. they are hard, [?] and tough. They are good [?] of electricity and heat. They are shiny and reflect [?].




Metal tubes are often used in the construction of [?]. The use of tubes has a number of advantages. They are [?] because they use less steel. They are [?] than using solid rods of steel. This gives a lower overall [?] for the bridge. The tubes are also stiffer and [?] than using flat sheets of steel. The bridge needs protection against [?] from the salt in the air, and this is provided by covering the bridge with a special [?].

[?] such as bricks, tiles and crockery, are strong in [?] by weak in tension. There are very [?] materials. Ceramics are very good [?] of electricity and heat.

[?] such as polythene, PVC and perspex are often flexible and they are strong for their [?]. They are usually soft and are easily [?]. They are excellent thermal and electrical [?]. They are usually transparent or [?].





Polymers are used widely in cars. They are lightweight, [?] and flexible. The plastic bumpers at the front to the car allow [?] to be absorbed during collisions. The plastic parts on the outside also prevent [?] from entering the vehicle. Plastic does not [?] when wet, unlike iron and [?].




Plastics are used widely in the clothes industry and fashion world. This is a plastic model kept outside in all weathers. It is durable and tough. Plastic with low [?] points would be unsuitable for the high [?] in the Summer. Many fashion clothes are made in plastic. They are not suitable for hot weather, unless provision is made for water [?] to escape from the body. Plastics are suitable for protection in wet weather because they are [?].


[?] materials consist of two or more different materials. Modern composite materials are usually made with fibres embedded in a [?]. This material protects the fibres from [?] and helps to share the [?] between all the fibres. The fibres provide [?] to the composite material. Carbon Fibre Reinforced Plastic (CFRP) is used widely in sports and the aircraft industry. They provide very high strength to [?] ratio. This allows structures to be light in weight but be very [?] and stiff.





Saving weight is important in aircraft. It allows the aircraft to carry more [?] or payload, and can increase the overall [?] and range of the aircraft.





This building, in Northern Arizona, is made from a composite material. It provides a streamline shape to withstand high [?]. It does not rot unlike [?], and it does not [?] unlike iron and steel. It is resistant to attack by termites, unlike wood. The fibreglass construction also provides good heat [?] . This allows the building to be [?] in cold weather, and [?] in hot weather.