Устное изложение

23. Изложите содержание текста:

If you are exhausted after a long walk, you may say that you've run out of energy. But your energy has not disappeared, it was converted into heat as you walked, and left behind in the air and the ground, making them slightly warmer. Indeed, it is impossible to destroy or create energy; it can only be moved or changed from one form to another. This is the Law of Conservation of Energy. What this means is that the total amount of energy alter any change is always exactly the same as the total before. Energy is really never lost: it is just converted to another form.

Energy is never lost, but it can be burnt up. Indeed, every time energy is used, some is turned into heat. This is why you feel hot after running and why light bulbs get hot. This matters because heat spreads thinly in all directions. So although energy is not lost, it is dissipated and is much harder to use again.

When wood burns, for instance, its energy is scattered through the air and is hard to use again. A little more becomes unusable this way each time energy is used — so the energy available to make anything happen (called free energy) gets less and less. Scientists use the word entropy to describe how much energy has become unusable. The less free energy there is, the greater the entropy. Entropy is at a maximum when there is no free energy left at all.

[1] Межконтинентальная баллистическая ракета — intercontinental ballistic missile (ICBM).

[2] Баллистическая ракета подводных лодок — submarine-launched ballistic missile (SLBM).

Дата добавления: 2015-07-16