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人教版高中地理必修2城市化精品教案
1．改善城市環(huán)境：治理河流、控制大氣污染物、大力加強綠化建設為改善城市環(huán)境，上海市全面展開對大氣、河流、噪聲等多方面的治理工作。如蘇州河的治理、降低城市污染物濃度、加強綠化建設，截止1990年，市區(qū)綠化覆蓋率達到20.3%。2．改善城市交通、改善居住條件擴寬主干道，修建環(huán)城公路，修筑了南浦大橋和揚浦大橋，新修城市高架公路和地鐵，改造住宅。3．控制城市規(guī)模建立衛(wèi)星城，開發(fā)新區(qū)，有效地控制城市中心區(qū)的規(guī)模。思考：什么時候許多國家采取措施保護和改善城市環(huán)境？你認為可以采取哪些措施來保護和改善城市環(huán)境？上海市保護和改善城市環(huán)境的措施：上海的衛(wèi)星城有哪些？上海新建了哪個新區(qū)？目前浦東新區(qū)在上海的地位如何？建立衛(wèi)星城和開發(fā)新區(qū)可以起到什么作用？上海市為改善交通條件，做了哪些工作？
人教版高中地理必修2工業(yè)地域類型教案
1．生產(chǎn)上的聯(lián)系：有投入——產(chǎn)出的關系工業(yè)生產(chǎn)的過程復雜，工序繁多，往往需要經(jīng)過多家工廠的加工才能完成一種產(chǎn)品的生產(chǎn)過程。因此，在這些工廠之間就存在著產(chǎn)品與原料的聯(lián)系。一家工廠生產(chǎn)的產(chǎn)品是另一家工廠的原料，這兩家工廠之間就形成了工序上的工業(yè)聯(lián)系。2．非生產(chǎn)上的聯(lián)系：如地理空間上的聯(lián)系布局在同一個工業(yè)區(qū)內(nèi)，共同利用工業(yè)區(qū)的道路、供水、供電、通信等基礎設施以及其他生產(chǎn)、生活服務設施，或者共同利用當?shù)亓畠r的勞動力，形成了空間利用上的工業(yè)聯(lián)系。我國許多地方的經(jīng)濟技術開發(fā)區(qū)就是建立在這種工業(yè)聯(lián)系基礎上的。（二）工業(yè)集聚1．形成具有工業(yè)聯(lián)系的一些工廠往往近距離地聚集起來，形成工業(yè)集聚現(xiàn)象。2．工業(yè)集聚可獲得效應（1）工業(yè)集聚可以加強企業(yè)間的信息交流和技術協(xié)作，降低中間產(chǎn)品的運輸費用和能源消耗，進而降低生產(chǎn)成本，提高生產(chǎn)效率和利潤，取得規(guī)模效益。
新人教版高中英語必修1Unit 2 Travelling Around-Reading and Thinking教案
Good expressions that students can choose to use: help the travelers choose which tour to take1. In my opinion, you could/might choose…, because you prefer to…2. …could be a perfect choice for you, for…3. As far as I am concerned, you would enjoy…, for…4. …would probably suit you, because you enjoy/love/hate doing…Step 5 Passage ConsolidationLanguage appreciation:1. You can then spend three days exploring the rainforest with a local guide and enjoying the plants and animals unique to the rainforest. 在接下來的三天里，您可以在當?shù)貙в蔚呐阃?，深入雨林進行探索，欣賞雨林特有的動植物。本句主體結構為spend some time doing sth. 2. Inca builders cut stones to exact sizes so that nothing was needed to hold walls together other than the perfect fit of the stones. 印加的建筑工人將石頭切割成精確的尺寸，僅僅憑著石頭間的完美契合，即可穩(wěn)固墻體。本句為so that引導的結果狀語從句。nothing與the perfect fit為并列成分; other than在句中意為“除了”。Step 6 HomeworkSuppose you will travel to Peru, write a short essay about your three-day tour plan.
新人教版高中英語必修2Unit 1 Cultural Heritage-Reading and Thinking教案一
The theme of the reading and thinking is about “Understanding how a problem was solved”.The Listening & Speaking & Talking is about international co-work to protect the Mount Tai, in which the students from seven countries came up with many solutions even create the Mount Tai App. This section aims at showing how to solve a difficult and even tough problem about protecting the cultural heritage by the international co-work. So in this section, cultivating students’ international awareness is very clear and important. Concretely, with the economic development, how to balance the protection of cultural relics and social development is a big challenge for human. In the 1950s, the Egyptian government wanted to build the Aswan Dam across the Nile to control floods, produce electricity and water farms. But the proposal led to protests because it would destroy a lot of cultural relics. The Egyptian had no choice but ask the UN for help. Therefore, a international cooperation about how to protect the cultural relics began, which involved the time length about 20 years and a large amount of fund. Then, the problems was solved. 1. Read quickly to get the main idea and the structure of the article; read careful to get detailed information.2. Learn to use the reading strategy---making a timeline3. Learn how to solve a tough problem by asking for help and cooperation4. Have the international awareness and understand the great strength of international cooperation.1. Read quickly to get the main idea and the structure of the article; read careful to get detailed information.2. Learn to use the reading strategy---making a timeline.3. Learn how to solve a tough problem by asking for help and cooperation.
新人教版高中英語必修2Unit 4 History and Traditions-Discovering Useful Structure教案二
This teaching period mainly deals with grammar: The past participle is used as attributive and objective complement.1. Guide students to review the basic usages of the past participle used as attributive and objective complement.2. Lead students to learn to use some special cases concerning the past participle used as attributive and objective complement flexibly.3. Strengthen students’ great interest in grammar learning.1. Help students to appreciate the function of the past participle used as attributive and objective complement.2. Instruct students to write essays using the past participle used as attributive and objective complement.Step1:溫故而知新。Analyze the underlined phrases and then sum up the common usages of the past participles.1．(教材P41)They had castles built(build) all around England, and made changes to the legal system．2．(教材P42)They use the same flag, known(know) as the Union Jack，．．．3．(教材P42)Judy and I had our car parked(park) in an underground car park near Trafalgar Square, where we could get our car battery charged(charge)．Common points: f the past participle used as attributive and objective complement.Step 2:過去分詞作定語時的意義1．及物動詞的過去分詞作定語，在語態(tài)上表示被動；在時間上，常表示動作已經(jīng)發(fā)生或完成，有時也不表示時間性。Our teacher watched us doing the experiment and gave us a satisfied smile at last．我們的老師看著我們做實驗，最后給了我們一個滿意的微笑。The plan put forward at the meeting will be carried out soon．會上提出的計劃將很快被執(zhí)行。2．不及物動詞的過去分詞作定語，它不表示被動意義，只強調(diào)動作完成。Many little kids like gathering fallen leaves in the yard．
新人教版高中英語必修2Unit 4 History and Traditions-Listening＆Speaking＆Talking教案二
Listening and Speaking introduces the topic of “Take part in a youth project”. The listening text is an interview about "sharing views on historical sites". Through listening to a dialogue between Chinese and foreign students on the way to the Confucius Temple, students can understand their views on the Confucius Temple, Confucius, Confucius' descendants and Confucius' educational thoughts, so as to realize and think about the profound influence of Confucius and his thoughts on Chinese historical tradition. At the same time, the dialogue naturally integrates English idioms and mentions Shakespeare, the British playwright, so as to provide language materials and context for students to understand English idioms and related cultural allusions, as well as to compare Chinese and foreign cultures, which is helpful for students to understand and express the language such as history, tradition, culture and custom significant impact.Text analysis: listening text is a dialogue between a British student and a Chinese student when he goes to the Confucius Temple. When William, a British student, visited the Confucius Temple, he asked Xiao Kong, a Chinese student, for directions. Xiao Kong was just going to the Confucius Temple to meet with the members of the research group, so they went together and exchanged their views on the Confucius Temple, Confucius, Confucius' descendants and Confucius' educational thoughts. From the perspective of foreign tourists, this paper describes their thoughts on Confucius, the great son of Confucius, who had a profound impact on Chinese history and cultural tradition, and his education.Listening and Talking introduces a visit to a historic tourist destination. Tourism is a common way to understand a country's history, culture, and customs and so on. Students listen to the dialogue between Xiao Yan, a youth hostel Usher, and Paul, a backpacker, to learn about Pingyao's famous historical and cultural attractions and Paul's travel experience and experience as a foreign tourist.
新人教版高中英語必修2Unit 4 History and Traditions-Reading and Thinking教案一
Features of languages1．Finally, in the 20th century, the southern part of Ireland broke away from the UK, which resulted in the full name we have today: the United Kingdom of Great Britain and Northern Ireland．該句是一個復合句。該句主句為：the southern part of Ireland broke away from the UK；which resulted in the full name we have today為which引導的定語從句代指前面整句話的內(nèi)容，we have today為定語從句修飾先行詞name。譯文：最后，在20世紀，愛爾蘭南部脫離英國，這導致了我們今天有的英國的全名：大不列顛及北愛爾蘭聯(lián)合王國。2．Almost everywhere you go in the UK, you will be surrounded by evidence of four different groups of people who took over at different times throughout history．該句是一個復合句。該句主句為：you will be surrounded by evidence of four different groups of people；其中Almost everywhere you go in the UK為讓步狀語從句； who took over at different times throughout history為定語從句修飾先行詞people。譯文：幾乎無論你走到英國的任何地方，你都會發(fā)現(xiàn)歷史上有四種不同的人在不同的時期統(tǒng)治過英國。3．The capital city London is a great place to start, as it is an ancient port city that has a history dating all the way back to Roman times．該句是一個復合句。該句主句為：The capital city London is a great place to start; as it is an ancient port city that has a history dating all the way back to Roman times．為原因狀語從句；dating all the way back to Roman times為現(xiàn)在分詞短語作定語修飾history。
新人教版高中英語必修2Unit 5 Music-Discovering Useful Structures教案二
4. When he got absorbed in his world of music, he felt as if he could “see” the beauty of the world around him, like he had in his previous life.P·P as adverbial: _________________________________________________________________.Function: _______________________________________________________________________.Step 5 Solid Complete the passage with the words in brackets in their correct forms.Well known as a successful band, the Impact members show quite a few striking qualities. They never ever give up. When _____________(question) by the media, they are not _____________(discourage) and practise even harder. They are improving themselves by attending several master training class. They are united. _____________(fill with) team spirit, they act as a whole, always aiming for glory. Step 6 Difference and similarity from -ingObserve the following examples.1. He went out, shutting the door behind him.=He went out, ________________________________________________________.2. Not knowing what to do, he went to his parents for help.=__________________________________________, he went to his parents for help.Similarity: _______________________________________________________________________________________________________________________________________________________.Difference : _______________________________________________________________________________________________________________________________________________________.Step Practice1. ________ in a hurry, this article was not so good. 因為寫得匆忙, 這篇文章不是很好。2. ________ carefully, he found something he hadn’t known before. 他仔細讀書時, 發(fā)現(xiàn)了一些從前不知道的東西。3. ________ why he did it, the monitor said it was his duty. 當被問及他為什么要這么做時, 班長說這是他的職責
新人教版高中英語必修2Unit 5 Music-Listening and Speaking教案
This lesson is about music. Students can classify the types of music through the instruments and its sound and can talk about their preferences about music, even join some activities and play a role in them according to their musical talents. On the basis, they are guided to use the languages to express their preferences and some plosive sounds and their rules.1. Classify the music types through the instruments and its sound.2. Listen and understand what the speakers’ preferences are and the reasons; talk about their own preferences and give their own reasons, using these sentences: “What kind of music do you like? And why? “ “Because it makes/gives me energy/peaceful.../touches my heart...”.3. Learn some plosives and the rules.4. Join some activities and play a role in them according to the talents. 1. Listen and understand what the speakers’ preferences are and the reasons;2. talk about their own preferences and give their own reasons, using these sentences: “What kind of music do you like? And why? “ “Because it makes/gives me energy/peaceful.../touches my heart...”.3. Learn some plosives and incomplete plosives and its rules.Step 1 Lead inPoint at the pictures on P50 and ask Q1: What are the people doing in the pictures below?Q2: What kind of music they are?Then play the MP3s one by oneStep 2 ListeningTask 1: A reporter from the school newspaper is interviewing students about music. Listen to the interviews. Draw lines between the words to make complete sentences. Some words will not be used.
新人教版高中英語必修2Unit 5 Music-Reading and Thinking教案二
1. Get basic information about Eric; read deeply to understand the history and development of the virtual choir.2. Understand what the function of the virtual choir is and how to make a virtual choir.3. Understand the meaning of some languages in the context of the text through question guidance, such as “Many people do not have close friends or contacts who have the same interest in music.” and so on.Step 1 Leading-in1. Answer the following questions.Q1：Do you know the Apps like Tik Tok and Quick Hand?Q2: Do you want to make a Tik Tok video or a Quick Hand video?2. Play a Tik Tok video Step 2: Understanding the title Q1：What does the title mean ?Q2: Is the article a narration or exposition? Why? Q3: Can you change the title ? If you can, what is the title?Step 3: Scanning the whole text and getting the basic information1. Answer the following questions.Q1：Who came up with the idea for a virtual choir?Q2: Where did Eric studied the musical composition?Q3: What is his song?2. Find the main idea of each paragraph3. Deal with some new words.Step 4: Reading carefully to get detailed informationPara 1 How to make a virtual choir1. PreparationA. tools: a virtual camera; an Internet connectionB. hero/heroin: friends or some individuals who have the same interests2. Process
人教版新課標高中物理必修1用牛頓運動定律解決問題（二）說課稿2篇
教師活動：（1）組織學生回答相關結論，小組之間互相補充評價完善。教師進一步概括總結。（2）對學生的結論予以肯定并表揚優(yōu)秀的小組，對不理想的小組予以鼓勵。（3）多媒體投放板書二：超重現(xiàn)象：物體對支持物的壓力(或對懸掛物的拉力)大于物體所受到的重力的情況稱為超重現(xiàn)象。實質(zhì)：加速度方向向上。失重現(xiàn)象：物體對支持物的壓力(或對懸掛物的拉力)小于物體所受到的重力的情況稱為失重現(xiàn)象。實質(zhì)：加速度方向向下。（4）運用多媒體展示電梯中的現(xiàn)象，引導學生在感性認識的基礎上進一步領會基本概念。4．實例應用，結論拓展：教師活動：展示太空艙中宇航員的真實生活，引導學生應用本節(jié)所學知識予以解答。學生活動：小組討論后形成共識。教師活動：（1）引導學生分小組回答相關問題，小組間互相完善補充，教師加以規(guī)范。（2）指定學生完成導學案中“思考與討論二”的兩個問題。
高中思想政治人教版必修三《文化創(chuàng)新的途徑》說課稿
二、說學情本課的教學對象為高二學生，他們思維活躍已具備一定歸納能力和分析、綜合能力，能夠自主地分析現(xiàn)實生活中的一些文化行為，但看問題往往比較偏激、片面，缺乏良好的邏輯思維能力。所以，在文化創(chuàng)新的途徑上要對他們進行指導，以免走入誤區(qū)。三、教學目標根據(jù)新課程標準、教材特點、學生的實際，我確定了如下教學目標：【知識與能力目標】1.理解文化創(chuàng)新的根本途徑和兩個基本途徑;2.了解文化創(chuàng)新過程中需要堅持正確方向，克服錯誤傾向。
人教版高中地理必修2第二章第二節(jié)不同等級城市的服務功能說課稿
【教學目標】知識與技能：了解我國不同等級城市的劃分，并理論聯(lián)系實際辨別現(xiàn)實社會的城市等級運用有關原理，說明不同等級城市服務范圍的差異。了解城市服務范圍與地理位置的關系。掌握不同等級城市的分布特點了解稱城市六邊形理論，并能用其解釋荷蘭圩田居民點設置問題過程與方法：通過對棗強鎮(zhèn)及上海城市等級演化分布的學習，掌握不同等級城市城市服務范圍與功能以及城市等級提高的基本條件通過對德國城市分布案例的學習，總結歸納出不同等級城市分布規(guī)律通過城市六邊形理論的學習，學會分析城市居民點布局等現(xiàn)實問題情感態(tài)度與價值觀：通過學生對我國不同等級城市（經(jīng)濟、人口、交通、服務種類）等相關資料的搜集，讓學生關心我國基本地理國情，增強熱愛祖國的情感。養(yǎng)成求真、求實的科學態(tài)度，提高地理審美情趣。
人教版高中地理必修2第四章第一節(jié)工業(yè)的區(qū)位因素與區(qū)位選擇說課稿
在這段教學中可以插入世界主要鐵礦、煤礦，以及我國主要的礦產(chǎn)基地、鋼鐵生產(chǎn)基地的相關內(nèi)容，不失為區(qū)域地理知識的很好補充和鞏固。那么從現(xiàn)狀來看我國的鋼鐵產(chǎn)業(yè)基地多數(shù)污染較為嚴重，可見工業(yè)區(qū)位的選擇同樣要顧及到環(huán)境的因素，由此引入下一部分的內(nèi)容。除了傳統(tǒng)意義上的工業(yè)區(qū)位因素外，環(huán)境、政策以及決策者的理念和心理等日益受到人們的關注。在這段文字的處理上，只需進行概念、道理上的陳述即可，重點要放在污染工業(yè)在城市中的布局這一知識點上。首先要了解什么工業(yè)會造成怎樣的污染，然后根據(jù)污染的類別分別講解不同的應對方略，最后將配以適當?shù)睦}以期提高學生的整體把握程度和綜合運用能力。最后將對本節(jié)內(nèi)容進行小結，要在小結中闡述清楚本節(jié)課的兩大內(nèi)容：即工業(yè)的區(qū)位因素和工業(yè)區(qū)位的選擇。然后點明本節(jié)課的主要知識點、難點、重點。在時間允許的情況下可以適當安排幾道有關主導產(chǎn)業(yè)和城市工業(yè)布局的例題加以練習。
人教版高中地理必修2第三章第二節(jié)以種植業(yè)為主的農(nóng)業(yè)地域類型說課稿
本節(jié)課標解讀：1.說明以種植業(yè)為主的農(nóng)業(yè)地域類型的形成條件及特點；2.說出商品谷物農(nóng)業(yè)的分布范圍，說明商品谷物農(nóng)業(yè)的形成條件及特點。內(nèi)容地位與作用：農(nóng)業(yè)是受自然環(huán)境影響最大的產(chǎn)業(yè)。農(nóng)業(yè)是發(fā)展歷史最悠久的產(chǎn)業(yè)，隨著社會的發(fā)展和進步，社會環(huán)境對農(nóng)業(yè)的影響越來越大。以季風水田農(nóng)業(yè)為主的農(nóng)業(yè)地域類型，主要體現(xiàn)自然環(huán)境對農(nóng)業(yè)地域形成的影響；商品谷物農(nóng)業(yè)則體現(xiàn)了社會環(huán)境對農(nóng)業(yè)地域形成的影響。本節(jié)內(nèi)容包括兩部分內(nèi)容，一個是季風水田農(nóng)業(yè)，主要分布在亞洲季風區(qū)；一個是商品谷物農(nóng)業(yè)，主要分布在發(fā)達國家。教材文字內(nèi)容不多，配備了大量的地圖和景觀圖。因此，在教學過程中要充分組織學生查閱地圖，挖掘地理信息，培養(yǎng)分析能力。分析農(nóng)業(yè)區(qū)位因素時，必須從自然因素和社會經(jīng)濟因素兩個方面去分析，找出優(yōu)勢區(qū)位因素來。
人教版高中地理必修2第三章第三節(jié)以畜牧業(yè)為主的農(nóng)業(yè)地域類型說課稿
1.導入新課：通過視頻“阿根廷的潘帕斯草原”，引起學生的興趣，進而引出新的學習內(nèi)容——以畜牧業(yè)為主的農(nóng)業(yè)地域類型。2.新課講授：第一課時，首先通過展示“世界大牧場放牧業(yè)分布圖”，引出對大牧場放牧業(yè)的初步認識，了解其分布范圍；然后通過展示“潘帕斯草原的地形圖”“氣候圖”和“牧牛業(yè)景觀圖”，討論分析大牧場放牧業(yè)形成的區(qū)位條件，并進行案例分析，學習該種農(nóng)業(yè)的特點；最后，理論聯(lián)系實際，展示：“中國地形圖”“氣候圖”“人口圖”“交通圖”和“內(nèi)蒙古牧區(qū)圖”，分組討論我國內(nèi)蒙古地區(qū)能否采用潘帕斯草原大牧場放牧業(yè)的生產(chǎn)模式。第二課時，首先通過設問順利從大牧場放牧業(yè)轉入乳蓄業(yè)，通過講述讓學生了解乳蓄業(yè)的概念；然后通過展示世界乳畜業(yè)分布圖，了解乳蓄業(yè)主要分布在哪些地區(qū)；接著，通過西歐乳蓄業(yè)的案例分析，得到乳蓄業(yè)發(fā)展的區(qū)位因素及其特點。
人教版高中語文必修2《親近自然寫景要抓住特征》教案2篇
一、教學目標1.指導學生以一顆真摯的童心、愛心面對大自然，促使學生的心靈與大自然親切交流。2.使學生明確寫景文章的寫作范圍、寫作重點、構思技巧。二、教學重難點明確話題，寫景抓住特征，注重感情。三、教學方法多重對話法四、教學過程1.導入語：自然是人類生活的環(huán)境，是人類賴以生存的基礎。人類不僅在物質(zhì)上需要大地母親的哺育，而且在精神上也需要向自然尋求依托。當知時節(jié)的春雨飄落大地時，當秋風吹來誘人的果香時，感到喜悅、幸福的決不僅是農(nóng)民；過去的政治家、文學家，每當失意的時候，就會寄情山林；就是我們中學生，當不堪學習重負，感到身心疲憊的時候，去野外踏青，不也能愉悅身心嗎？可以說人對自然的情懷是與生俱來的。但不同的人，對自然的感悟有深淺不同，情趣有高下之分?！叭f類霜天競自由”的感悟，“大漠孤煙直”的審美不是人人都能有的。2.面對大自然，通過什么樣的手段來促使我們的感悟、審美向高深方向發(fā)展呢？哪位同學說說。
人教版高中語文必修2《想象世界學習虛構》教案2篇
虛構不等于說假話。它是一種源于生活，但高于生活的藝術真實。我們可以舉個例子：我國公認的最權威最真實的史書是——《史記》，那么，大家認為《史記》里有沒有虛構呢？有。必修一的《鴻門宴》里就有虛構。大家想：司馬遷是哪個朝代的人？西漢漢武帝時。劉邦項羽是哪個朝代的？秦末時期。那司馬遷不可能坐時光穿梭機到秦末去參加鴻門宴吧？既然他沒不在場，那課文《鴻門宴》里人物的語言、動作、甚至是表情從何而來呢？對，是司馬遷根據(jù)有限的史料加以補充，想象、虛構出來的。那么，同學們在寫作文時，也可以不必拘泥于親身經(jīng)歷的事情，畢竟生活是平淡的，畢竟大家的生活閱歷也有限，有時候，我們發(fā)揮想象、虛構一個故事來反映生活的真實，也許更生動、也更典型。所以，近年來高考試卷中都提示考生：作文可以大膽想象，編寫故事。按照編故事的方式不同，我們的虛構性作文又可以寫哪些類型呢：小說，散文，童話，寓言，科幻，故事新編……
人教版高中地理必修2城市內(nèi)部空間結構精品教案
過渡：在實際生活中，城市內(nèi)部空間結構并非完全按照這一經(jīng)濟規(guī)律呈現(xiàn)，而是更具復雜性。這說明除了經(jīng)濟因素外，還有很多其他因素在起作用，請大家結合你的認識、圖2．9和案例1：紐約市的少數(shù)民族區(qū)談談你的看法。（2）其他因素I.收入 —— 形成不同級別住宅區(qū)的常見原因。有能力支付昂貴租金和選擇最佳居住環(huán)境的人，其居住地往往形成高級住宅區(qū)。II.知名度 ——城市內(nèi)某些地區(qū)在歷史、文化或經(jīng)濟方面具有很高的聲譽，這往往會吸引更多新的住宅或商場建在該處，以提高其知名度。III.種族聚居區(qū)的形成 ——在有些城市的某一區(qū)域內(nèi)，如果某個種族或宗教團體占優(yōu)勢，就可能形成種族聚居區(qū)。如紐約市的唐人街、哈林區(qū)、小意大利區(qū)等。IV歷史因素——城市的建筑物和街道設計可以維持久遠，早期的土地利用方式對日后的功能分區(qū)有著深遠的影響。3、城市內(nèi)部空間結構的形成和變化
人教版新課標高中物理必修2機械能守恒定律教案2篇
（二）進行新課1、動能與勢能的相互轉化演示實驗1：如右圖，用細線、小球、帶有標尺的鐵架臺等做實驗。把一個小球用細線懸掛起來，把小球拉到一定高度的A點，然后放開，小球在擺動過程中，重力勢能和動能相互轉化。我們看到，小球可以擺到跟A點等高的C點，如圖甲。如果用尺子在某一點擋住細線，小球雖然不能擺到C點，但擺到另一側時，也能達到跟A點相同的高度，如圖乙。問題：這個小實驗中，小球的受力情況如何？各個力的做功情況如何？這個小實驗說明了什么？學生觀察演示實驗，思考問題，選出代表發(fā)表見解。小球在擺動過程中受重力和繩的拉力作用。拉力和速度方向總垂直，對小球不做功；只有重力對小球能做功。實驗證明，小球在擺動過程中重力勢能和動能在不斷轉化。在擺動過程中，小球總能回到原來的高度?？梢?，重力勢能和動能的總和保持不變。即機械能保持不變。
