What is energy?
Wherever you are sitting as you read this, changes are taking place: light bulbs are heating the air around them, the wind might be rustling leaves, or sunlight might be glaring off.
Every change that occurs—large or small—involves energy. Imagine a baseball flying through the air. It hits a window, causing the glass to break. The window changed from a solid sheet of glass to a number of broken pieces. The moving baseball caused this change—a moving baseball has energy. Even when you comb your hair or walk from one class to another, energy is involved.
In science energy is defined as the ability to do work. Work is done when a force causes something to move. One also can define energy as the ability to cause change. When work is done, something moves and a change occurs. When work is done and a change occurs, energy moves from place to place or changes from one form to another.
Turn on an electric light, and a dark room becomes bright. Turn on your CD player, and sound comes through your headphones. In both situations, energy moves from one place to another. These changes are different from each other. This is because energy has several different forms—electrical, chemical, radiant, and thermal. Each of you can name and show some examples of everyday situations which involve forms of energy. Is the chemical energy stored in food the same as the energy that comes from the Sun or the energy stored in gasoline? Radiant energy from the Sun travels a vast distance through space to Earth, warming the planet and providing energy that enables green plants to grow. When you make toast in the morning, you are using electrical energy. In short, energy plays a role in every activity that you do.
If we push a book across the desk so that it accelerates, we give the book an impulse – we apply a force on the book for a period of time. However, the book also moves some distance during this time. That is, we also apply the force across a distance. Whenever we apply a force on an object across a distance, we say that we are doing work on that object. Work is the transfer of energy to an object by applying a force to the object through some distance. When we do work on the object, we change some condition of the object, either its position in space or its velocity. If we change its position, such as lifting a mass above the surface of the earth, the work we do is stored as gravitational potential energy. If we change its velocity, the work is stored as kinetic energy.
Ex.13. Translate the following words and word combinations into English using your active vocabulary:
включать (электрический свет); объект; сила; звук; перенос (передача) энергии; применять силу; происходить, случаться; тепловая энергия; химическая энергия; обогревать (нагревать) планету; ослепительно сверкать, ярко светить; условие; скорость; положение в пространстве; наушники; бензин; импульс; энергия излучения солнца; накапливать энергию; поверхность Земли.
Ex.14. Translate into English:
Когда мы что-то делаем, нам нужна энергия.
Студент выступает с докладом на конференции. В течение около 1 часа он рассказывает об электроэнергии как об одном из видов энергии.
Давай включим телевизор и посмотрим новости.
Без тепловой энергии нельзя жить.
Какие виды энергии Вы знаете? – Мне известны многие виды энергии, например, химическая энергия, электроэнергия, тепловая энергия, кинетическая энергия, потенциальная энергия, а также радиационная энергия или, как ученые еще называют ее, энергия излучения солнца.
Без энергии излучения солнца растения не могут расти.
Не могу понять, как люди жили в течение многих и многих веков, и даже тысячелетий без электроэнергии. – Да, согласен. Мне тоже трудно понять это. Почти все удобства современной жизни были невозможны.
Тропическое солнце ослепительно сверкало почти целый день. Было очень жарко и неприятно.
Все туристы устали от жары и ослепительного солнечного света. Всем хотелось найти тень. Но ее нигде не было до самой ночи.
Включите ваши CD-плейеры и прослушайте рассказ о тепловой энергии и ее значении для жизни на Земле.
Ex.15. Retell the text “What is Energy?” in English in 10-12 sentences.
Ex.16. Listen to the dialogue and “At the stadium” and decide whether the statements are true or false:
The group visited the biggest sports complex in Detroit.
Football League games were played at the stadium every season from late summer to June.
They wanted to watch a soccer game.
The complex had four swimming pools.
They could rent any sports equipment.
They decided to go straight to the hotel after the game.
You should be a member to do aerobics.
The game was between Alabama and Florida.
Ex.17. Explain in English what is the difference between:
a spectator and a participant
football in Europe and football in the USA
Ex.18.Role play:
A group of American students have come to your university on an exchange program. They are fond of sport. Tell them about the facilities the university has and what sports activities they can do there.