Английский язык. Ч. 1. Ильичева Н.А - 14 стр.

                                           14
                                        Test 5 (unit5)
                                            Heat

     A. Reading.
     You are going to read the text about heat. Choose a sentence from the list
A-E which best summarises each part (1-6) of the text.

      A. The mechanical equivalent of a particular amount of heat.
      B. Physical definition of heat.
      C. Heat flow is directed from an object at higher temperature to an object at
lower temperature.
      D. Heat is a form of energy produced as the result of mechanical work.
      E. The meaning of the word “heat” accepted in everyday life.

       1. . We use the term “heat” in everyday life as if we knew what we meant.
The heating effects produced by fire, the sensation received when a piece of ice is
held and the warmth produced when hands are rubbed together are well known. But it
is not easy to explain what take place in each of these cases.
       2. . We commonly speak of the “flow” of heat. Heat flows spontaneously
from an object at higher temperature to one at lower temperature: from a stove burner
to a pot of coffe, from the Sun to the Earth. Indeed, an eighteenth-century model of
heat pictured heat flow as movement of a fluid substance called caloric. However, the
caloric fluid was never to be detected.
       3. . Count Rumford was one of the first to recognize the relation between the
mechanical work and heat. He used a blunt boring tool to drill a cannon barrel im-
mersed in water. The temperature of the cannon and water rose to the boiling point in
two and one-half hours. Large quantities of heat were produced by friction. It con-
vinced Rumford that heat was a form of energy and appeared to be due to the motion
of a drill.
       4. . Later James Prescott Joule, an English scientist determined the quantita-
tive relationship between mechanical energy and heat. Joule determined that a given
amount of work done was always equivalent to a particular amount of heat input.
Quantitatively, 4, 186 joules (J) of work was found to be equivalent to 1 calorie (cal)
of heat.
       5. . As a result of these and other experiments, scientists came to interpret
heat not as a substance and not even as a form of energy. Rather, heat refers to a
transfer of energy: when heat flows from a hot object to a cooler one, it is energy that
is being transferred from the hot to the cold object. Thus, heat is energy that is trans-
ferred from one body to another because of a difference in temperature.

      B. Choose the correct item o fill in the gaps:
      1. The…………flow of the heat is always in the direction to equalize the tem-
perature. (impulsive, spontaneous, unforced)
      2. Enegry…………involves work. (shift, movement, transfer)
      3. The…………forces of materials are different. (internal, inner, interior)