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Unformatted text preview: Thermal Expansion One of the main sources of stresses in an object is heat. Here we begin to study some of the properties of heat. We are all familiar with the ideas that an object is hot or cold. In order to quantify this, we introduce the notion of temperature . Thus, for a certain amount of "hotness" we can associate a number. This leads to the concept of a temperature scale . Temperature Scales In order to define a temperature scale, we need to make certain assumptions. The first one is that there will be a linear relationship between how hot an object is and its temperature. This allows us to specify two points on the scale and divide the rest of the scale evenly. There are two main scales used in the U.S. today. The first one is the Fahrenheit scale. It takes the freezing point of water and associates the number 32 with it, and it associates the number 212 with the boiling point of water. Thus, there are 180 degrees between the freezing and boiling points of water. The other main scale is the Celsius , or Centigrade , scale. It is the main temperature scale used in the rest of the world, and is the main temperature scale used in technological work in the U.S. In this scale the freezing point of water is defined to be at 0 degrees, and the boiling point is defined to be 100 degrees. Notice however, that neither of these scales actually refers to any physical properties of water. Instead, two arbitrary points for an arbitrary material were chosen and used to define the scale. We can define a temperature scale that uses the physical properties of matter, the absolute temperature scale. The Celsius version of the absolute scale is the Kelvin scale. Similarly, the absolute version of the Fahrenheit scale is the Rankine scale. All of these scales can be related to one another. All of these scales can be related to one another....
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