II. READING (20 points). a) Put the following words into the certain gaps: a) stronger; b) elastic; c) to lift; d) original; e) materials; f) tension; g) section; h) ruptures;

a) Put the following words into the certain gaps:

a) stronger; b) elastic; c) to lift; d) original; e) materials; f) tension; g) section; h) ruptures; i) importance; j) industry.

 

MECHANICAL PROPERTIES

Although the latest developments in 1) … science have tended to focus on electrical properties, mechanical properties are also of major, continuing 2) …. For the aircraft 3) …, for instance, scientists have been developing, and engineers testing, nonmetallic composite materials that are lighter, 4) …, and easier to fabricate than the aluminum and other metals currently used to form the outer skin of aircraft.

5) … (or tensile) stresses develop when a material is subjected to a pulling load; for instance, when using a wire rope 6) … a load or when using it as a guy to anchor an antenna. “Tensile strength” is defined as resistance to longitudinal stress or pull and can be measured in pounds per square inch of cross 7) …. Under tension, a material usually stretches, returning to its 8) … length if the force does not exceed the material's 9) … limit. Under larger tensions, the material does not return completely to its original condition, and under even greater forces the material 10) ….

b) Define whether these sentences are true (T) or false (F):

1. Mechanical properties as well as electrical properties are important in materials science.

2. Under larger tensions a material returns to its primary state.

3. Aluminium is lighter than nonmetallic composite materials.

4. The result of tension under larger forces is rupture.

5. “Tensile strength” is measured in pounds per square inch.

6. The latest developments in materials science are stressed on electrical properties only.

7. Composite materials are considered to be lighter and easier to fabricate comparing with aluminium.

8. An example of tensile stress is a wire rope when raising a load.

9. The resistance to longitudinal stress or pull is the definition of creep.

10. Composite materials are used for making outer skin of aircraft.

Total Score – 40 points