Make up situations using the English equivalents of the words given above. 25. Give Russian equivalents to the following word combinations:

25. Give Russian equivalents to the following word combinations:

Water pumps; spinning water; the blades of the impeller; to rise in pressure; centrifugal pump; to make possible; compressed air; water hammer; empty space; pumping action; turning blades; to provide the pressure surge; stationary environment

26. Work in pairs and decide whether these statements are true or false:

1. The water pumps in most cars are cylindrical ones.

2. As the water spins, the pressure near the outer edge of the pump housing becomes much higher than that near the center of the impeller.

3. You can also view the water as a compressible fluid, one that doesn’t obey Bernoulli’s equation.

4. Actually, faster moving fluids don’t necessarily have higher pressure.

5. Since the flow is faster near the center of the flow, it is difficult to calculate the volume flowing each second.

6. When a column of water is allowed to accelerate downhill through a pipe until it’s flowing at a good speed through the pipe, it then closes a valve at the lower end of the pipe, so that the water has to stop abruptly.

7. When the compressed air is then used to push water through the pump’s outlet and provide the pumping action, this pumping scheme is called a «hydraulic ram».

8. When a fluid is flowing smoothly and steadily through a stationary environment, its energy is concerned.

9. When the fluid slows down, its kinetic energy does not drop so its pressure potential energy (and its pressure) must drop too.

10. As the water column inside the pipe grows taller, a new problem appears: gravity.

11. If water speeds up during its flow, the water’s pressure or height or both must decrease.

27. Fill in the gaps with the prepositions/conjunctions from the box:

When you draw water up through a pipe (or straw) ___ removing the air inside that pipe, you are allowing the atmospheric pressure ___ the water to push the water up the pipe. The water experiences a pressure imbalance ___ the pressure around it (atmospheric pressure) and the pressure ___ the pipe (less than atmospheric pressure), so it accelerates ___ the pipe. But as the water column inside the pipe grows taller, a new problem appears: gravity. The water’s weight pushes downward and begins to oppose the pressure imbalance. ___ a certain height, the two effects balance and the water stops accelerating upward. When the water’s height reaches 10 m, atmospheric pressure can’t overcome this weight problem, even ___ all the air has been removed from the pipe.

28. Work in pairs, make as many questions as possible to review the contents of the text below and ask each other:

History of Drinking Water Treatment

Humans have been storing and distributing water for centuries. Before, when people lived as hunters/collectors, river water was applied for drinking water purposes. When people permanently stayed in one place for a long period of time, this was usually near a river or lake. When there were no rivers or lakes in an area, people used groundwater for drinking water purposes. This was pumped up through wells. When the human population started growing extensively, the water supply was no longer sufficient. Drinking water needed to be extracted from a different source.

About 7000 years ago, Jericho stored water in wells that were used as sources. People also started to develop drinking water transport systems. The transport took place through simple channels, dug in the sand or in rocks. Later on one also started using hollow tubes. Egypt used hollow palm trees and China and Japan used bamboo strunks. Eventually one started using clay, wood and even metal.

In Perzia people searched for underground rivers and lakes. The water went through holes in rocks into the wells on the plains.

Around 3000 B.C., the city of Mohenjo-Daro (Pakistan) used a very extensive water supply. In this city there were public bathing facilities with water boiler installations and bathrooms.

In ancient Greece spring water, well water, and rainwater were used very early on. Because of a fast increase in urban population, Greece was forced to store water in wells and transport it to the people through a distribution network. The water that was used was carried away through sewers, along with the rainwater. When valleys were reached, the water was lead through hills under pressure. The Greek were among the first to gain an interest in water quality. They used aeration basins for water purification. The Romans were the greatest architects and constuctors of water distribution networks in history. They used river, spring or groundwater for provisioning. The Romans built dams in rivers, causing lakes to form. The lake water was aerated and than supplied. Mountain water was the most popular type of water, because of its quality. For water transport the aquaducts where built. Through these aquaducts water was transported for tens of miles. Plumbing in the city was made of concrete, rock, bronze, silver, wood or lead. Water winnings were protected from foreign pollutants.

After the fall of the Roman Empire, the aquaducts were no longer used. From 500 to 1500 A.D. there was little development in the water treatment area. In the Middle Ages countless cities were manifested. In these cities wooden plumbing was used. The water was extracted from rivers or wells, or from outside the city. Soon, circumstances became highly unhygenic, because waste and excrements were discharged into the water. People that drank this water fell ill and often died. To solve the problem people started drinking water from outside the city, where rivers where unpolluted. This water was carried to the city by so-called water-bearers.

The first drinking water supply that supplied an entire city was built in Paisley, Scotland in 1804 by John Gibb, in order to supply his bleachery and the entire city with water. Within three years, filtered water was transported to Glasgow. In 1806 Paris operated a large water treatment plant. The water settled for 12 hours, before it was filtered. Filters consisted of sand and charcoal and where replaced every six hours.

In 1827, the Englishman James Simpson built a sand filter for drinking water purification. Today, we still call this the number one tribute to public health.