The three remaining basic machines are so related to one another that they are sometimes grouped together. They are the wedge, the inclined plane, and the screw.

The wedge is a triangle with two chief surfaces that meet in a sharp angle or taper to a thin edge. Wedges are used for splitting open or pushing apart. They were used from very early times for such purposes as quarrying rock, plowing fields or cut­ting wood, as with an axe. A nail is a familiar form of the wedge.

The inclined plane is the probable method employed by the Egyptians for manipulating into place the huge blocks of stone in the pyramids. The inclined plane is an important factor that concerns civil engineers when designing highways or railroads. The mechanical engineer more frequently uses the screw, a spiral form of the in­clined plane.

The screw was used in ancient times to press grapes for wine or olives for oil. In the Middle Ages it was important in the develop­ment of printing. Today we are most familiar with the screw as a fastener.

Pulley	ролик
Groove	борозна, жолоб
Block and tackle	поліспаст, натяжні блоки
To suspend	вішати, підвішувати
Wedge	ріжучий клин, лезо
Inclined plane	похила площина
Screw	болт
Triangle	трикутник
To split	розколювати
Taper	конус, предмет конічної форми
To quarry	розробляти кар’єр, добувати каміння з кар’єру
To plow	орати
Fastener	з’єднувальна деталь

Comprehension check.

1. What is the third basic machine?

2. What was this device used for in ancient times?

3. What is a block and tackle and what can it do?

Explain how a movable pulley acts as a lever of the second class.

5. What are wedges used for? What were some early uses of the screw?

Complete the following sentences with the appropriate word. Translate the sentences.

Fasteners, split, hoist, screws, a pulley

1. The crew hurried to ____________ the flag.

2. __________ is a piece of equipment consisting of a wheel over which a rope or chain is pulled to lift heavy things.

3. Rutherford first _________the atom on 3^rd January 1919.

Fix the frame in position and tighten the ___________.

The company produces high-quality steel wire for ________and for the furniture industry.

Give English equivalents.

Ролик, натяжні блоки, принцип важільного механізму, рухомий валик, ріжучий клин, розробляти кар’єр, орати поля, цвях, спіральна форма, душити виноград для вина.

Insert the appropriate pronouns.

1. She was sitting alone. She wasn't with_____.

2. I heard a knock on the door but when I opened it there was____outside.

3. It's dark. I can't see________.

4. Tom lives_________near London.

5. Do you know_________about computers?

6. 'Listen! ' 'What? I can't hear_________.'

7. 'What are you doing here?' 'I'm waiting for________'

8. 'What's wrong?' 'I've got______in my eye.'

9. 'Did.................................................... you see ___________?' 'No,____________'

10. They weren't hungry, so they didn't eat_________.....................................

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