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III. Writing Section. 1. Translate the following text from English into Russian




1. Translate the following text from English into Russian. Use a dictionary of necessary.

 

Concept of Temperature

 

The sense of touch helped man to obtain the primary motion of temperature. Touching various bodies with our hands we sometimes say “a cold body” or “a warm body” to denote the degree of heating to which the body had been subjected. The quantity characterizing the degree of heating to which the body had been subjected is termed the temperature of this body.

The determination of temperature by touch is not objective and may be the cause of error. Indeed, if we press a naked hand against two objects lying on a table, of which one is made of plastic and the other of metal, we will say that the metal object is cooler although in actual fact the temperature of both objects is the same. Therefore to measure temperatures objectively a special instrument termed thermometer was invented.

The temperature of every body is closely related to the energy of motion of its molecules. The physical meaning of the concept of temperature is as follows: the higher the temperature of the body, the greater the average kinetic energy per molecule of this body. Experience shows that when two bodies with different temperatures are in contact, the body with the higher temperature always gets cooler and the body with the lower temperature always gets hotter. This means that energy exchange takes place between the bodies, ceasing when the temperatures of the bodies become equal. Such exchange of energy is termed heat exchange. Hence, by measuring the temperatures of the bodies we can find out beforehand which bodies will receive heat in the course of heat exchange and which will give it away. If the temperatures of the bodies measured will prove to be equal, this will mean that the energy of each of them remains constant. This makes temperature a valuable concept.

Since the kinetic energy of a molecule is proportional to the square of its velocity, heating a body results in the increase in the average velocity of its molecules; the result of cooling is a decrease in it.

A person’s sense of heat and cold is also due to heat exchange between him and the surrounding medium. If the temperature of the object you touch exceeds that of your hand, energy is transmitted from the object to the hand. If, on the other hand, the object’s temperature is lower, heat is transmitted from your hand to the object. The more rapid this exchange of energy is the more intense is your perception of heat or cold.

Now we can understand why the metal object appeared to be colder than the plastic one. The explanation is that the energy transfer from the hand to the metal object was more rapid than in the case of the plastic object and the temperature of the hand in the first case dropped quicker than in the second.





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