The second law says that if you draw heat from a reservoir to raise a weight, lowering the weight will not generate enough heat to return the reservoir to its original temperature, and eventually the cycle will stop. If two blocks of metal at different temperatures are thermally insulated from their surroundings and are brought into contact with each other the heat will flow from the hotter to the colder. Energy has not been lost, but instead some energy has been transferred from one block to another.
You. are to add to the diagram the necessary information.
HEAT
| WORK |
Match the words with their definitions.
1. heat
2. work
3. transition
4. boundary
5. reservoir
a) something that indicates the farthest limit, as of an area; border
b) the energy transferred as a result of a difference in temperature
c) the transfer of energy expressed as the product of a force and the distance through which its point of application moves in the direction of the force
d) a natural or artificial lake or large tank used for collecting and storing water
e) any change that results in a change of physical properties of a substance or system, such as a change of phase or molecular structure
Make up sentences.
1. Transition, heat, in, represent, work, energy, and.
2. Energy, heat, is, as, result, the, difference, a, of, transferred, temperature.
3. 1903, in, Max Planck, was, the, law, second, of, described, by, Thermodynamics.
6. Complete the following sentences.
1. Work is the transfer of energy...
2. Heat is energy transferred...
3. Heat can be transferred...
4. The Second Law of Thermodynamics denies...
5. It is impossible to construct an engine...
6. The second law says that...
Answer the following questions.
1. What is the main difference between heat and work?
2. How do they work?
3. What peculiarities have you noticed?
Ask the given sentence as many questions as possible.
The Second Law of Thermodynamics was described by Max Planck in 1903.
Translate the sentences into English.
1. Робота - це передача енергії, яке є результатом дії сили через відстань.
2. Тепло - енергія, яка передається в результаті різниці температури.
3. Тепло може бути передане у або з системи, а робота може бути зроблена над системою, або самою системою, але система не може містити або зберігати тепло чи роботу.
4. Другий закон термодинаміки був описаний Максом Планком у 1903 році.
5. Енергія не була втрачена, але замість того вона була передана від одного блоку до іншого.
Unit 5
HEAT AND WORK
1. Memorize the following words and expressions:
Ø to reside - знаходитись
Ø paddles - мішалка measurement – вимір
2. Read the text, study it Find in the text examples to illustrate difference between key notions: heat and work.
Heat and Work Example
Heat may be defined as energy in transit from a high temperature object to a lower
temperature object. An object does not possess "heat"; the appropriate term for the microscopic energy in an object is internal energy. The internal energy may be increased by transferring energy to the object from a higher temperature (hotter) object - this is properly called heating.
This example of the interchangeability of heat and work as agents fox- adding energy to a system can help to dispel some misconceptions about heat. In the article by Mark Zemansky entitled "The Use and Misuse of the Word 'Heat' in Physics Teaching" there is one key idea that if you are presented with a high temperature gas, you cannot tell whether it reached that high temperature by being heated, or by having work done on it, or a combination of the two.
To describe the energy that a high temperature object has, it is not a correct use of the word heat to say that the object "possesses heat" - it is better to say that it possesses internal energy as a result of its molecular motion. The word heat is better reserved to describe the process of transfer of energy from a high temperature object to a lower temperature one. Surely you can take an object at low internal energy and raise it to higher internal energy by heating it. But you can also increase its internal energy by doing work on it, and since the internal energy of CONVERSION OF WORK TO I HERMAL ENERGY a high temperature object resides in random motion of the molecules, you can't tell which mechanism was used to give it that energy. The First Law identifies both heat and work as methods of energy transfer which can bring about a change in the internal energy of a system. Heat flow and work are both ways of transferring energy. The temperature of a gas can be raised either by heating it, by doing work on it, or a combination of the two. In a classic experiment in 1843, James Joule showed the energy equivalence of heating and doing work by using the change in potential energy of falling masses to stir an insulated container of water with paddles. Careful measurements showed the increase in the temperature of the water to be proportional to the mechanical energy used to stir the water. At that time calories were the accepted unit of heat and joules became the accepted unit of mechanical energy. Their relationship is.
Complete the sentences.
1. Heat may be defined as...
2. The internal energy may be increased by...
3. If you are presented with a high temperature gas, you cannot tell...
4. The word heat is better reserved...
5. The First Law identifies both heat and work as...
4. Write down as many questions to the given sentences as possible.
1. In a classic experiment in 1843, James Joule showed the energy equivalence of heating and doing work by using the change in potential energy of falling masses to stir an insulated container of water with paddles.
2. Heat flow and work are both ways of transferring energy.
3. The temperature of a gas can be raised either by heating it, by doing work on it, or a combination of the two.
5. Say if the statements are true or false;
1. Work may be defined as energy in transit from a high temperature object to a lower temperature object.
2. The appropriate term for the microscopic energy in an object is external energy.
3. It is better to say that a high temperature object possesses internal energy as a result of its molecular motion.
4. The internal energy may be increased by transferring energy to the object from a higher temperature (hotter) object.
5. You can take an object at low internal energy and raise it to higher internal energy by heating it.
Answer the questions.
1. How may be heat defined?
2. 2 How is heating properly called?
- Can we tell whether gas reached that high temperature by being heated or by having work done on it. or a combination of the two?
- What is better to say: an object "possesses heat" or "possesses internal energy"? Why?
- W hat experiment was done in 1843?
- What does the first Law of Thermodynamics indicate?
