V. Comprehension.

Exercise 1. Find the wrong statements and correct them:

1. One for of energy can not be transformed into another

2. Potential energy is the energy of motion.

3. Kinetic energy is the energy of position.

4. Changes in the forms of energy are called energy conversions.

5. When an object loses its potential energy that energy is turned into kinetic energy.

6. The sun is a limited source of energy.

Exercise 2. Give short answers to the following questions:

1. Can one form of energy be changed into another form?

2. Does a generator produce mechanical energy?

3. Is the sun an unlimited source of energy?

4. Can we employ solar energy directly?

5. Have scientists transformed solar energy into electric energy?

6. Is potential energy the energy of motion?

7. Do we need more and more electric energy every year?

8. Are there various forms of energy?

9. Do you use electric energy every day?

10. Can the energy of falling water be used to drive turbines?

11. Is kinetic energy the energy of position?

VI. Practice.

Exercise 1.

1. Speak of different forms of energy.

2. Give example when potential energy is turned into kinetic energy.

VII. Reading and Practice.

Exercise 1. Read the text B for 3 minutes and find the English equivalents to the following Ukrainian words combinations:

1) Електрика, вироблена такою установкою коштує дешевше, ніж...;

2) ... були сконструйовані для перетворення сонячної енергії в електричну;

3) кількість сонячної енергії на один квадратний метр тут рівна енергії, виробленої... .

Text B.

Harnessing solar energy

The experiments on solar cells gave the possibility to collect enough data to predict the possible performance of solar stations. These experiments have led to the building of a solar furnace developing temperatures of 3.000 C in a sunray focal point. Electricity generated by such an installation costs less than that generated by a steam power station.

The solar stations in the Kara-Kum desert will become producers of cheap electricity in the near future. The amount of solar energy per square meter here is equal to the energy generated by burning 200 kg of high quality coal. Power cells of the size of a matchbox have been developed to convert solar energy into electricity. Such cells can accumulate sufficient energy in one bright day to power a large transistor radio for ten days.

Exercise 2. Point out which of the sentences contains the information from the text B.

1) It is quite possible that some day coal and the other fuel may be replaced by atomic energy.

2) Solar station will produce cheap electric energy in the near future.

3) The experiments on atmospheric electricity were made by many outstanding scientists.

Exercise 3. Read text C and point out the main idea of each paragraph.

Text C.

Conservation of Energy

You have just read of many conversions of energy: kinetic and potential in the ball, heat and chemical in fuels, heat and mechanical in engines. Perhaps you have wondered if any energy is lost during such conversions. The answer is that in spite of all the changes of form, the total amount of energy remains the same.

The law of conservation (kahn-ser-VAY-shuhn) of energy states that energy can be neither created nor destroyed by ordinary means. Energy can only be converted from one form to another. So energy conversions occur without loss or gain in energy.

The law of conservation of energy is one of the foundations of scientific thought. If energy seems to disappear, then scientists look for it. Important discoveries have been made because scientists believed so strongly in the conservation of energy.

One such discovery was made by Albert Einstein in 1905. Part of his famous theory of relativity dealt with the concept that mass and energy were interchangeable. Einstein expressed this concept in the form of a mathematical equation: E=mc²

«E» - is energy, «m» - is mass, and «c» - is the speed of light. According to this equation, the energy of any mass is equal to the product of that mass and the square of the speed of light.

With this mass—energy relationship, Einstein was saving that matter is another form of energy, or that mass and energy are two forms of the same tiling and can be converted into each other. With this mass—energy relationship, Einstein modified the law of conservation of energy. He showed that if some of either matter or energy is created or destroyed, the other must make up for the change. The total amount of mass and energy is conserved.

During nuclear reactions—such as those that take place in the sun—energy and mass do not seem to be conserved. But Einstein used his famous equation to show that a loss in mass results in a gain in energy. Mass is continuously changed to energy in our sun through a process called nuclear fusion. During this process, a small loss in mass produces a huge amount of energy.

Exercise 1. Answer and explain on the following:

1. What is the law of conservation of energy?

2. Explain the meaning of Einstein’s equation E= mc^2.

3. Why does even a small loss in mass result in a tremendous gain in energy?

Exercise 2. Comment on the following:

During certain nuclear reactions, a high – speed electron is ejected. The energy lost by the nucleus, however, does not equal the energy of the escaping electron. From this observation, scientists concluded that another undiscovered particle must also be ejected. They searched for more than 20 years before they found it. Why did the scientists believe another particle must exist?

Unit 2