1. All known elements are made up of very small particles, known as atoms, which, when joined together, form molecules.
2. Molecules are in a constant state of motion."
3. Water, for example, may exist in any one of these states.
Answer the following questions.
What is heat?
Does it exist in every substance on earth?
What are all known elements made up of?
What do carbon and hydrogen form in certain combinations?
Molecules are in a constant state of motion, aren't they?
What states of a substance do you know?
What states of water do you know?
What happens to a substance when heat is added?
Translate the sentences into English.
1. - 㳿, .
2. , '.
3. .
4. - , .
5. , , , .
Unit 2
UNIT OF HEAT. TEMPERATURE
1. Memorize the following words and expressions:
Ø kinetic energy -
Ø potential energy -
Ø average -
Ø to measure -
Ø to be made up of -
Ø to relate -
Ø to double -
Read and retell the text.
Heat and Temperature
Knowing the difference between heat and temperature is important if one is to have a clear understanding of energy. In this section we will define both terms and reach an understanding of how they are related ideas, but not identical ideas. What follows are some beginnings, and then some links to further explanations and animations.
A Wrong Idea.
Often the concepts of heat and temperature are thought to be the same, but they are not.
Perhaps the reason the two are usually and incorrectly thought to be the same is because as human beings on Earth everyday experience leads us to notice that when you heat something up, say like putting a pot of water on the stove, then the temperature of that something goes up. More heat, more temperature - they must be the same, right? Turns out, though, this is not true.
Initial Definitions
Temperature is a number that is related to the average kinetic energy of the molecules of a substance. If temperature is measured in Kelvin degrees, then this number is directly proportional to the average kinetic energy of the molecules.
Heat is a measurement of the total energy in a substance. That total energy is made up of not only of the kinetic energies of the molecules of the substance, but total energy is also made up of the potential energies of the molecules.
More About Temperature.
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So, temperature is not energy. It is, though, a number that relates to one type of energy possessed by the molecules of a substance. Temperature directly relates to the kinetic energy of the molecules. The molecules have another type of energy besides kinetic, however; they have potential energy, also. Temperature readings do not tell you anything directly about this potential energy.
Temperature can be measured in a variety of units. If you measure it in degrees Kelvin, then the temperature value is directly proportional to the average kinetic energy of the Temperature molecules in the substance. Notice we did not say that temperature is the kinetic energy; We said it is a number, if in degrees Kelvin, is proportional to the 100-average kinetic energies of the molecules; that is, if you double the Kelvin temperature of a substance, you double the average kinetic energy of its molecules.
