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第32讲：热膨胀Lecture 32: Heat - Thermal Expansion |
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| 课程网址: | http://videolectures.net/mit801f99_lewin_lec32/ |
| 主讲教师: | Walter H. G. Lewin |
| 开课单位: | 麻省理工学院 |
| 开课时间: | 2008-10-10 |
| 课程语种: | 英语 |
| 中文简介: |  |
| 课程简介: | **1. Heat and Temperature:** Various temperature scales are discussed: Celsius, Fahrenheit, Kelvin. **2. Linear Thermal Expansion:** The linear thermal expansion coefficient is introduced. Expansion leads to a need for expansion joints in railroad rails to avoid bulging on hot days. Thermal expansion is demonstrated by heating and cooling a brass rod. An important application of thermal expansion is bi-metals which are used in thermostats, safety devices and thermometers, as demonstrated. **3. Cubical Thermal Expansion:** The fractional change in volume with temperature is given by the coefficient of cubical expansion. A mercury thermometer is discussed. **4. Shrink Fitting:** Shrink fitting is a technique that makes use of the thermal expansion by heating one object (of two). After the two objects are assembled, they cool, and the fit is perfect and "for ever". **5. Cubical Thermal Expansion of Water:** Water has a maximum density at 4 degrees Celsius; between 0 and 4 degrees Celsius the cubic thermal expansion coefficient is negative so the water expands as it cools below 4 degrees Celsius. The density of ice is about 8% lower than water, so ice cubes and icebergs float in water. |
| 关 键 词: | 热膨胀; 线性热膨胀; 水的立方热膨胀 |
| 课程来源: | 视频讲座网 |
| 最后编审: | 2019-05-23：lxf |
| 阅读次数: | 63 |