18 Ответьте на следующие вопросы, представив соответствующую ситуацию.

1You meet your professor. What would you say? 2 1 don't know how to operate this machine-tool. What would you do? 3 1 don't know where the main shop of this plant is. Where could I get the answer? 4 We have broken our car. What would you do in our place? 5 You don't know how to make this drawing. Who would you consult? 6 First I studied at the medical college, but I like engineering best of all. So 1 dropped my studies at the medical college and went to the auto-mechanical institute. What would you do in my place?

19 Раскройте скобки и поставьте глагол в нужную форму сослагательного на­клонения.

1 If they (use) another method, the results would have been different. 2 If the complete list of details had been prepared the engineer (buy) everything in time. 3 If the load (increase) the speed would decrease. 4 If all the people of the world (count) the atoms in a drop of water they would not be able to finish their work even in ten thousand years. 5 If one knows the dimensions of the body he (calculate) easily its volume. 6 If every star in the sky were to shine with the same degree of brightness, the distance to any star (can) readily be established. 7 If he (know) the specific heat and the weight of the substance, he would have calculated its thermal capacity. 8 If you rubbed the stick, it (become) warm.

20 Закончите предложения.

1 If I graduated from the Institute now, I would go to work to KAMAZ. If 1 went to work to KAMAZ, I would... 2 If I were the chief engineer of the plant, I would... 3 If there were no machine-tools, there wouldn't be... 4 If there were no electricity, there would be... 5 If I worked at the scientific research institute, I would..

TEXT STUDY

21 Подготовьте развернутые ответы на следующие вопросы.

1 What is a simple definition of a machine? What is a more technical definition? What does this definition imply? 2 Describe some very simple machines. Name some complex machines. 3 What do we call machines whose input is a natural source of energy? What natural sources of energy do you know and what machines use them? 4 Why aren't electric motors prime-movers? 5 What is force? Give some examples of force. 6 What is work? How can work be expressed mathematically? Give an example. 7 What is power? 8 How is the rate of doing work usually given in the English-speaking countries? Why was the term invented? 9 In what terms is power measured in the metric system?

22 Сделайте краткое сообщение на тему "Machine, Work, Power". При подготовке используйте активный словарь.

23 Прочитайте текст и определите:

а) в каком абзаце текста дано упрощенное описание работы четырехтактного двигателя внутреннего сгорания;

б) сколько рабочих циклов д. в. с. упоминается в тексте; в каком (каких) абзаце (абзацах).

TEXT 4B

Engine

An engine produces power by burning air and fuel. The fuel is stored in a fuel tank. The fuel tank is connected to a fuel pipe. The fuel pipe carries the fuel to a fuel pump. The fuel pump is connected to the carburettor. The fuel pump pumps the fuel into the carburettor. In the carburettor the fuel is mixed with air. The fuel and air are drawn into the engine cylinder by the piston. Then the fuel and air are compressed by the piston and ignited by the spark plug. They burn and expand very quickly and push the piston down. Thus the power is produced. The burned fuel and air are expelled from the cylinder by the piston.

The flow of gases into and out of the cylinder is controlled by two valves. There is an inlet valve allowing fresh fuel mixture into the cylinder and an exhaust valve which allows the burnt gases to escape.

There are two basic engine operating cycles:

1. the four-stroke cycle;

2. the two-stroke cycle.

The complete four-stroke cycle comprises:

1. the induction stroke (the piston moves downwards);

2. the compression stroke (the piston moves upwards);

3. the power stroke (the piston moves downwards);

4. the exhaust stroke (the piston moves upwards).

There are some basic types of fuel for motor vehicles. There is diesel fuel, there is petrol and there is fuel mixture.

Most motorcycles have two-stroke petrol engines. But there are a few motorcycles with four-stroke petrol engines. There are no motor­cycles with diesel engines.

A lot of buses have diesel engines but only a few cars have such engines. There are also a few cars with two-stroke engines but most cars have four-stroke petrol engines.

Most lorries have diesel engines. There are not many lorries with four-stroke petrol engines but there are no lorries with two-stroke engines.

A lot of engines are at the front of the car. A few engines are at the back and very few are in the middle.

Notes

a stroke: the distance travelled by the piston (upwards or downwards) in the cylinder

t. d. с (top dead centre): the position of the piston at the top of the stroke

b. d. с (bottom dead centre): the position of the piston at the bottom of the stroke