I V. Look and read:

a tube is hollow a rod is solid

a curved surface a flat surface

The power station building is hollow. It has five flat external

surfaces.

Now describe these buildings and components in a similar way:

a) The church

b) The slab

c) The column

d) The mosque

e) The steel beam

V. Now describe the shapes of the buildings in exercise I, and compare them with the buildings around you.

Lesson 9

Properties of material

Noun	Adjective	Examples of materials
weight	a light material a heavy material	•aluminium, magnesium lead, copper
flexibility rigidity	a flexible material a rigid material	thin sheets of metal, plastics stone, cast iron
combustibility	a combustible material	rubber, plastic
fire resistance	a non-combustible material	clay, glass
transparency	a transparent material	water, some plastics
opacity	an opaque material	Stone
corrosion resistance	a corrosion resistant material a material which is not corrosion resistant	zinc, chromium, tin cast iron
conductor conductivity	a good conductor of heat a poor conductor of heat	silver rubber
elasticity	an elastic material	Nylon
plasticity	a plastic material	copper, aluminium
softness	a soft material	rubber, nylon
hardness-	a hard material	cast iron

I. Look at these examples:

A man can easily lift a large roll of

glass wool but not a concrete beam.

Glass wool is light but concrete is

A man can bend a rubber tile but not a concrete tile.

Rubber is flexible but concrete is rigid.

Wood can burn but concrete cannot burn.

Wood is combustible but concrete is non-combustible.

Water vapour can pass through stone but not through bitumen.

Stone is permeable but bitumen is impermeable.

You can see through glass but not through wood.

Glass is transparent but wood is opaque.

Stainless steel can resist corrosion but mild steel cannot.

Stainless steel is corrosion resistant but mild steel is not corrosion resis­tant.

Heat can be easily transferred through copper but not through wood.

Copper is a good conductor of heat but wood is a poor conductor of heat.

Rubber can be stretched or com­pressed and will then return to its original shape but clay cannot.

Rubber is elastic but clay is plastic.

Bitumen can be dented or scratched easily but glass cannot. Bitumen is soft but glass is hard.

Look at these diagrams. Match the letters A-H in the diagrams with the sentences below:

Now complete these sentences with properties:

a) The polythene membrane can prevent moisture from rising into the concrete floor. This means that polythene is _______.

b) The T- shaped aluminium section can resist chemical action, i. e. aluminium is ……..

c) The stone block cannot be lifted without using a crane. This means that stone is ___________.

d) The corrugated iron roof cannot prevent the sun from heating up the house, i. e. iron is ……….

e) Glass wool can help to keep a house warm in the winter and cool in the summer, i. e. glass wool is ………

f) The ceramic tiles on the floor cannot be scratched easily by people walking on them. This means that ceramic tiles are ___

g) Asbestos sheeting can be used to fireproof doors. In other words asbestos is ________ .

h) Black cloth blinds can be used to keep the light out of a room, i.e. cloth is ________ .