3. Physical and some other properties of Materials.

a) Read and remember new words:

attract [əʹtrækt]  v притягувати, приваблювати

cause [kƆ:z] v спричиняти

compound [ʹkƆmpaund] n суміш

corrode [kəʹrəud] v роз’їдати, іржавіти

corrosion [kəʹrəuʒ(ə)n] n корозія

density [ʹdensiti] n щільність, концентрація

distinguish [disʹtiŋgwi∫] v відрізняти

liquid [ʹlikwid] n рідина

melt [melt] v плавити

observer [əbʹzə:və] n спостерігач

opaque [ouʹpeik] adj непрозорий, світлонепроникний

optical [ʹƆtik(ə)l] adj оптичний

patch [pæt∫] (of light) n пляма, уривок

ratio [ʹrei∫iəu] n коефіцієнт, співвідношення

resistance [riʹzist(ə)ns] n опір

solid [ʹsƆlid] n тверде тіло

specific gravity [ʹgræviti]  n питома вага

thermal [ʹθə:m(ə)l]  adj термальний, тепловий

b) Read and analyze the text.

Physical and Some Other Properties of Materials

Materials may be useful because of their physical and other properties. Some of these include:

Density is the weight of a material per unit volume.

Specific gravity is the ratio of the mass or weight of a solid or liquid to the mass or weight of an equal volume of water.

Melting point is the point at which a material liquefies on heating or solidifies on cooling. Some materials have a melting range rather than a single melting point.

Color is the property of light by which an observer may distinguish between two structure-free patches of light of the same size and shape.

Other properties.

Chemical properties. These have to do with how a material reacts to chemical compounds. Corrosion resistance is a chemical property. This tells how well a material resists the chemical reactions caused by air and water. Iron will corrode, but aluminum will not.

Optical properties. A material’s optical properties have to do with how it reacts to light. Opaque materials do not allow light to pass through. Some opaque materials, such as aluminum foil, reflect light.

Electrical properties. Materials that allow electricity to pass through easily are called conductors. Copper and gold are good conductors.

Thermal properties. How does a material react to heat? Those are its thermal properties. Most metals conduct heat well. They are used in radiators.

Magnetic properties. Some materials are attracted to magnets. Iron is an example. Other materials, such as aluminum, do not react to magnets at all.

c) Answer the following questions.

1. What Chemical properties of Materials do you know?

2. What are Electrical properties?

3. How do Materials react to heat?

4. What Materials are attracted to magnets?

5. What are Physical properties of Materials?

d) Discuss the problem of physical and other properties of materials.

4. Properties of Materials.

1. Analyze the table “Properties” below.

Properties

Mechanical

Hardness

Fatigue

Tensile

Impact

Creep

Wear

Stiffness

Compression

Shear

Physical

Density

Electrical

Magnetic

Conduction

Expansion

Flammability

Melting point

Chemical

Environmental resistance

Composition

Bonding

Structure

Dimensional

Flatness

Surface finish

Stability

Critical size