一、考题回顾

题目
一、考题回顾



二、考题解析
【教学过程】
环节一:新课导入
复习比热容的概念,随后教师提出问题:如果知道一种物质的比热容,再知道这种物质的质量和温度升高的度数,如何计算它吸收的热量?引出课题。
环节二:新课讲授
1.吸热计算公式
教师通过多媒体呈现实际问题1:已知铝的比热容是0.88×103J/(kg·℃),这表示质量是1kg的铝块温度升高1℃时吸收的热量是0.88×103J。计算:把质量为2kg、温度为30℃的铝块加热到100℃,铝块吸收的热量是多少?引导学生从比热容的概念入手,进行小组合作和讨论,尝试解决这一问题。
学生通过合作交流,得出解题思路:(1)由比热容定义可知,质量是2千克的铝块温度升高1℃时吸收的热量是2×0.88×103J;(2)质量是2千克的铝块温度升高70℃时吸收的热量就是70×2×0.88×103J。
接着,教师追问学生:如果以Q吸代表物体吸收的热量,c代表物质的比热容,m代表物体的质量,t0和t分别是加热前后物体的温度,根据上面的计算过程,能否总结出一个物体吸热的一般公式?
学生经过自主探究,得出结论



2.放热计算公式
教师通过多媒体呈现实际问题2:有一根烧红的铁钉,温度是800℃,质量是1.5g。它的温度降低到20℃,要放出多少热量?引导学生思考此题和问题1的区别是什么。
学生得出结论:问题1是物质升温,求吸收的热量,问题2是物质降温,求放出的热量。
教师组织学生自主探究问题2的解决方法,并根据吸热公式写出物质降温时所放出热量的一般计算公式,并和吸热公式进行比较。
学生得出结论:



和吸热公式相比,放热公式是用初始温度减去末温度。
3.吸放热一般公式
教师提出问题:物质吸热或放热的多少和哪些因素有关?
学生根据吸热、放热公式得出结论:物质吸热或放热的多少和物质的种类、质量以及温度的变化有关。此时教师顺势指出:如果用



表示温度变化,那么可不可以用一个公式表示物质吸热或放热的多少?
学生得出结论:物质吸热、放热的公式可以写成



环节三:巩固提高
教师出示例题:质量为2kg的某种物质温度从20℃升高到40℃时,吸收的热量是1.88×104J,该物质的比热容是多少?
环节四:小结作业
老师提问学生这节课的收获。学生总结物质吸热、放热的计算公式。
作业布置:根据物质的比热容表,计算质量均为2kg的砂石和水,都吸收了7.36×104J的热量,那么它们升高的温度各是多少?
板书设计


参考答案和解析
答案:
解析:
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相似问题和答案

第1题:

一、考题回顾



答案:
解析:
二、考题解析
【教案】
Teaching aims:
Knowledge aim:
Students will master the meaning and pronunciation of the words.
Ability aim:
Students will know how to pronounce “ch” and “sh” in words.
Emotional aim:
Students will be interested in learning English.
Key and difficult point:
Key Point:
Students will master the meaning and pronunciation of the words.
Students will know how to pronounce “ch” and “sh” in words.
Difficult Point:
Students will be interested in learning English.
Teaching procedure:
Step 1: Warming-up
1. Greetings. Talk about the weather.
2. Chant with the students



Ask them if they remember the first step in the chant. They may say that it is to “wash” the tomato. Then tell them that today we are going to learn some pronunciation in it.
Step 2: Presentation
1. Draw some pictures according to different words, and then explain the meanings to the students.
2. Play the finger show with the students to consolidate the words. For example, finger 1 refers to “chicken”, and finger 2 refers to “lunch”. When the teacher points finger 1, the students should read “chicken” loudly. The rest could be done in the same manner.
3. Ask students to find similarities and differences among the words. They may say that in the first two words, there is “ch” in the words, while in the last two words, there is “sh” in the words. And they pronounce similarly.
4. Conclude the rules of “ch” and “sh”. Tell them that when they see “ch”, they should pronounce [t?], and when they see “sh”, they should pronounce [?]. They may sound similar, but they are different. Please be notice that.
Step 3: Practice
1. Ask a few students if there are other words containing “ch” or “sh”. They may answer “chopsticks”, “ship” or “shop”.
2. Read the words in a different order, and ask students to rank the words according to the listening. At the same time, invite one students to come to the front and write the words down on the blackboard. Check answers later.
Step4: Production
Ask students to make up dialogues with their deskmates. 5 minutes will be given. After that, invite 2 pairs to share their dialogues. Give encouragement.
Step5: Summary and Homework
Summary: Ask a student to conclude the content of the lesson and summarize with the whole class.
Homework: Read the words to their parents.
Blackboard design:



【答辩题目解析】
1. What will you do to help students master the pronunciation of what we need to learn?
【参考答案】
First, they should know how to pronounce the syllables. So I will pronounce them in a clear way to make sure that they notice the place of articulation. I will correct their pronunciations if they make some mistakes. Then, I ask them if they know other words sharing the same syllables. Also, few activities were arranged to make them really use the rules. So I believe they will master the rules of the pronunciations.
【答辩题目解析】
2. What will you do if the students can’t focus on your class?
【参考答案】
There are some options to deal with the problem. First, I could arrange some interesting activities to stimulate their interest. Second, when imparting some knowledge, I could show some examples closely related to their daily lives. They will be interested in familiar things. Third, I could ask some students to answer my questions from time to time, so they will be more focused in case of being asked. So I will try to use the most appropriate method to attract their attention.