Energy Transformation. Varieties of Energy

There are many sources of energy in the world both potential and kinetic. One source consists in water falling from high level such as an upland lake. Another source is wind or moving air. Others are in tides in the sea, also heat from subterranean sources and lastly coal deposits and oil wells yielding mineral oil. But all these sources and stores of energy are not equally useful to mankind. Moreover, some stores of energy such as coal and oil can never be replaced by us when once used up. On the other hand stores of high level water are continually being replaced by rain and wind and tides will not, as far as we know, ever cease to exist.

Hence a very important matter is the conversion of energy from one form to another. The form most required by us is mechanical energy.

We require to rotate shafts in a factory for driving various ma­chines and also for driving the wheels of vehicles of automobiles or locomotives. The energy of water power is very unequally distributed. Some countries such as Norway and Switzerland are rich in it and some such as England are poor.

Appliances for converting energy from one form to another are called engines. Thus a heat engine is a machine for converting heat into mechanical energy by the combustion of coal or oil and a water engine (water turbine) can convert the kinetic energy of falling water into mechanical energy. Another important matter to all such engines and transformation is the question of their efficiency or the ratio of the energy delivered in the desired form to that given to the engine in the available form. Thus, for instance, in the case of a heat engine we give it so much heat by combustion of coal or oil, and we take from it so much mechanical energy in kinetic form rotational or mo­tional and the important question is the ratio of the latter to the form­er. In most cases it is very small [2, С. 98].

2.12.8 Look through texts 2.12 and find the English equivalents for the following Russian phrases and word-combinations:

теплота тесно связана с мо­лекулярным движением; мы можем вполне подозревать; ударьте по концу гвоздя молотком раз десять (слово dozen - дюжина в русском переводе заме­няется словом десяток или десять в тех случаях, когда не имеется в виду строго определенное число); вследствие частоты столкновений между молекулами; движения совершенно беспоря­дочны; почти то же самое случается, когда; мы должны также учитывать её (потенциальную энергию); наиболее привычная температура; из-за того факта, что; удельная теплоемкость (теплота) вещества; чтобы найти ее, топливо помещается в; не важно насколько быстро подводится тепло; в нижней части сосуда; на дне; действует утверждение того факта, что теплота; наоборот; для того, чтобы предотвратить; работают по тому же принципу.