论文部分内容阅读
一、复习,归纳出本章的主要内容。概述本堂课主要复习第二章“热膨胀热传递”。[板书]“复习‘热膨胀、热传递’”[演示]用酒精灯加热烧瓶,水从玻璃管口A处喷射出来(图1)。[提问]用酒精灯对烧瓶加热以后,水为什么会喷射出来?(学生解释)[讲述]不但空气会受热膨胀,一般的物体都具有热胀冷缩的性质。[板书]“一、热膨胀”[提问]用酒精灯对烧瓶加热时,玻璃也会膨胀,烧瓶的容积会增大,但为什么水还会从玻璃管中喷出来呢? 待学生回答后教师小结:在相同的条件下,固体膨胀得最小,液体膨胀得较大,气体膨胀得最大。[板书]“ 1.物体热膨胀的特点”[讲述]物体的热膨胀在生产和生活中有着广泛的应用。课本上介绍的常用温度计就是
First, review, summarize the main content of this chapter. Overview This class mainly reviews Chapter 2 “Thermal heat transfer.” [Writing book] “Review ’thermal expansion, heat transfer’” [Demonstration] The flask was heated with an alcohol lamp and water was sprayed from the glass mouth A (Fig. 1). [Question] Why does water spray out after heating the flask with an alcohol lamp? (Student explained) [Description] Not only does the air expand by heat, but the general objects have the property of thermal expansion and contraction. [Writing book] “I. Thermal expansion” [question] When the flask is heated with an alcohol lamp, the glass will expand and the volume of the flask will increase, but why the water will be ejected from the glass tube? : Under the same conditions, the solid expands minimally, the liquid expands more, and the gas expands the most. [Board] “1. Characteristics of thermal expansion of objects” [Description] Thermal expansion of objects has a wide range of applications in production and life. The common thermometer introduced in the textbook is