Listening and Speaking introduces the topic of “how to save endangered wildlife and help wildlife in their neighborhood.” Due to the continuous deterioration of the living environment, a large number of wild animals are always facing the threat of endangered or extinction. Listening and speaking period enables students to understand the fact and reason why wild species are disappearing from the earth at an amazing speed, and realize that human beings ought to enhance the awareness of protecting wild species as soon as possible.Listening and Talking introduces the theme of " how to help wildlife in Ss’ neighborhood.". Now there are many volunteers who spontaneously protect wild animals, carry out various activities according to local conditions, and contribute their own strength to local animal protection with practical actions. Middle school students are also enthusiastic participants. They organize activities in their spare time, and take this opportunity to make friends, broaden their horizons, cultivate team spirit and communication skills. This section describes a bird watching activity organized by several middle school students of Bird watching Club. It aims to stimulate students' interest, improve their understanding of bird watching activities, and use the language structure of “being used for; in order to, so as to, to, so that, in order that ” to express the purpose for communication and discussion.1. Guide students to understand the content of listening texts in terms of using visuals to predict content.2. Cultivate students' ability to guess the meaning of words in listening; discuss with their peers how to save endangered wildlife and help wildlife in their neighborhood.3. Instruct students to use functional sentences of the dialogue such as “I am concerned about…” “what do you know about the endangered animals in…" and so on to talk about one of the endangered animals.
This lesson is about wildlife protection. The listening and speaking is about “How to protect endangered wildlife ?” Faced with the facts and numbers of wildlife loss, people begin to detect the reasons, then people such as the celebrities (Prince William and Yao Ming) are calling on to protect them. So students are guided to enhance the awareness of protecting wildlife and try to take part in some volunteer activities of protecting wildlife.1. Predict the content by using visuals. 2. Learn to use the sentences such as “I’m concerned about.... But now they are in danger. I want to know the reasons/why./ What can we do to protect them ?3. Learn from the stars like Prince William and Yao Ming and enhance the awareness of protecting wildlife.4. Guide students to try to put forward the solutions to the problems of wildlife protection and then discuss them with partners and present the results of discussion.5. Master the pronunciation of stressed syllables.1. Learn from the stars like Prince William and Yao Ming and enhance the awareness of protecting wildlife.2. Guide students to try to put forward the solutions to the problems of wildlife protection and then discuss them with partners and present the results of discussion.3. Learn to use the sentences such as “I’m concerned about.... But now they are in danger. I want to know the reasons/why./ What can we do to protect them ?4. Master the pronunciation of stressed syllables.Part A Listening and Speaking--- How to save endangered wildlifeStep 1 Lead in1. Point at the pictures on P14 and ask Q1: What message do these posters share?
The theme of this unit is human and nature, focusing on the theme of wildlife protection. Nature is a complex ecosystem, in which there are delicate balance between animals and plants. Because of the role of the food chain, the extinction of one species will produce influence, causing a series of chain reaction. Large scale extinction of species will have a serious and even irreversible impact on the ecosystem, resulting in immeasurable losses. Therefore, it is of great significance to protect wild species. To protect wild species is to protect human beings themselves. The motto of this unit is "when the buying stops, the killing can too,” which is a public service advertising slogan to protect wildlife. It tells people that every rhinoceros horn, every fur, every bowl of shark fin soup, every Ivory product, and every tiger bone product, etc. consumed by human beings, are innocent wild animals slaughtered behind them. The mission of wild aid is to ban illegal trade in endangered wildlife and mitigate climate change. It aims to educate the public to reduce the consumption demand for endangered wildlife products through public publicity and improve the awareness of environmental protection.1. Improve the awareness of wildlife protection by acquiring the knowledge of wildlife protection.2. Focus on environmental protection and protection of all lives.3. Analysis of the living environment of wild animals with appropriate thinking mode.4. Skillfully use the vocabulary and grammar knowledge of this unit to cultivate self-study ability according to the unit content5. Develop cooperative learning ability through discussion and other ways1. Enable the Ss to talk about the current situation of wild animals.2. Guide the Ss to summarize the main idea of each paragraph as well as the main idea of the text.
1. 標(biāo)題首先根據(jù)海報(bào)的特點(diǎn)、格式寫明標(biāo)題。海報(bào)中往往把內(nèi)容作為大標(biāo)題。例如: Save the earth, Save the birds。2. 正文部分不同的海報(bào)其正文部分的側(cè)重點(diǎn)不同。對(duì)于介紹性的海報(bào), 首先要引出話題, 其次列出原因, 最后是總結(jié)。對(duì)于宣傳類的海報(bào), 要寫明具體內(nèi)容, 如: 活動(dòng)內(nèi)容, 地點(diǎn)以及參加活動(dòng)的注意事項(xiàng), 主持或舉辦單位等。1. 圖片: 要選擇引人注目的圖片, 與主題要相關(guān), 色彩明亮。話題句式 1. It is a treasure of our country. 它是我國(guó)的國(guó)寶。2. Believe it or not, at present only several thousand pandas exist in the world. 信不信由你, 目前世界上僅現(xiàn)存幾千只熊貓。 3.It’s because of human activities that tigers are endangered. 正是因?yàn)槿祟惖幕顒?dòng), 老虎處于瀕危的狀態(tài)。4. Many wild animals are in danger of dying out. 很多野生動(dòng)物面臨著滅絕的危險(xiǎn)。 5. The government has taken effective measures to protect them. 政府已采取有效的措施來(lái)保護(hù)它們。6. People should raise the awareness of the protection of wild animals. 人們應(yīng)該提高保護(hù)野生動(dòng)物的意識(shí)。 7. It’s amazing that there are merely less than 1, 000 finless porpoises living in China. 非常令人吃驚, 目前中國(guó)僅有不足1 000只江豚。
Step 5 Practice一、完成下列句子。1. Judy and I _______________(把車停下來(lái)(park))in an underground car Park near Trafalgar Square, where we could ______________________(讓我們的車充電(charge)).2. When we finally reached the service desk to ask for audio guides, we heard it ___________ that there were no audio guides____________(留下,剩下).3. We__________________________(發(fā)現(xiàn)自己對(duì)...很驚訝)the large number of visitors and the amount of noise at the entrance of the National Gallery.4. Judy ____________________(眼神專注于) Van Gogh’s Sunflowers. It was hard to approach the painting as there were so many people around.5. She ____________________(把這幅畫的復(fù)制品裝箱(box)) to ensure that it was delivered safely.答案:1.had our car parked get our car battery charged 2. announced left 3. found ourselves very surprised 4. had her eyes fixed on 5. had a copy of the painting boxed二、用過(guò)去分詞對(duì)下列句子進(jìn)行改寫。1. Loch Ness was surrounded by beautiful natural landscape, which made it look amazing.2. Carl and his friend stayed with a generous family who offered them bread with butter and honey that was homemade.3. The family’s ancestors once attended to soldiers who were wounded in the First World War.4. The young people were attracted by the legend of Loch Ness. They watched over the lake with their cameras and binoculars, which were positioned on the hill.答案:1. Loch Ness surrounded by beautiful natural landscape looks amazing.2. Carl and his friends stayed with a generous family who offered them homemade bread with butter and honey.3. The family’s ancestors once attended to wounded soldiers in the First World War.4. The young people attracted by the legend of Loch Ness watched over the lake with their cameras and binoculars positioned on the hill.
This unit is about history and traditions. From the opening page, we can know that this unit will introduce the history and traditions around the world. As Marcus Garvey says “A people without the knowledge of their past history, origin and culture is like a tree without roots”, it is important for students to realize the importance and value of knowing the history and traditions and their further meanings. And this part ( listening and speaking ) is divided into two parts: Part A---share views on historic sites, Part B ---talk about a visit to a historic tourist destination. By talking with a foreigner, the speakers introduce the historic attractions and their cultures. Part A is that William, a British student, who was going to visit the Confucius Temple and a Chinese student, Xiao Kong, who was going to the Confucius Temple to meet with the members of the research group, went together and exchanged their views on the Confucius Temple, Confucius, Confucius' descendants and Confucius' educational thoughts. Part B is a conversation between Xiao Yan, a youth hostel receptionist and Paul, a backpacker about the feelings and experience after visiting the Chinese famous tourist attraction Pingyao.1. Guide students to understand the content of listening texts in terms of the whole and key details; 2. Cultivate students' ability to guess the meaning of words in listening; discuss with their peers how to talk about historic spots and great person.3. Instruct students to use functional sentences of showing one’s excitement, surprise and disappointment.1. Guide students to understand the content of listening texts in terms of the whole and key details; 2. Cultivate students' ability to discuss with their peers the related topics.3. Enable students to use the functional items of showing one’s excitement, surprise and disappointment.
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(gè)復(fù)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(dǎo)的定語(yǔ)從句代指前面整句話的內(nèi)容,we have today為定語(yǔ)從句修飾先行詞name。譯文:最后,在20世紀(jì),愛(ài)爾蘭南部脫離英國(guó),這導(dǎo)致了我們今天有的英國(guó)的全名:大不列顛及北愛(ài)爾蘭聯(lián)合王國(guó)。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(gè)復(fù)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(yǔ)從句; who took over at different times throughout history為定語(yǔ)從句修飾先行詞people。譯文:幾乎無(wú)論你走到英國(guó)的任何地方,你都會(huì)發(fā)現(xiàn)歷史上有四種不同的人在不同的時(shí)期統(tǒng)治過(guò)英國(guó)。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(gè)復(fù)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(yǔ)從句;dating all the way back to Roman times為現(xiàn)在分詞短語(yǔ)作定語(yǔ)修飾history。
Step 1 Lead inThere are many interest of places in the UK. What do you know ?The Big Ben the London Tower the Thames RiverStep 2 Before reading---analyze the titleBeautiful Ireland and its traditionWe know that the article mainly tells about the beauty and traditions of Ireland. Step 3 While reading---Task 1Read the text and answer the following questions.Q1: What makes the Irish countryside exciting and inspiring?Its beauty and how it offers something for all the scenes.Q2: What are the best ways to experience some Irish traditions and cultures?By stopping by a village pub and relaxing with a drink and traditional meal while listening to music and watching dancingQ3: What is the meaning of “breathe in the sweet scent of fresh flowers while birds greet the new day with their morning song ?”It means to not just smell but also breathe in the smell of fresh flowers early in the morning as the birds sing their first song of the new day.Q4: What are the best ways to experience Chinese traditions and customs ?By travelling to different places and using all your senses to experience everything and by interacting with local people.Step 4 While reading---Task 2Analyze the descriptive paragraph1. Identify and underline the paragraph’s introductory sentence and the ending sentence.Introductory sentence: Ireland’s beautiful countryside has always had a great influence on its people and traditions.Ending sentence: And if you introduce yourself to a friendly face, you are more than likely to experience local culture and customs first-hand.2. The paragraph talks about different senses in different places. Write the senses and places in the order that they appear.
這個(gè)地區(qū)有著深厚的傳統(tǒng)。既學(xué)既練:為了讓更多的外國(guó)游客了解中國(guó)文化,欣賞中國(guó)美麗的自然風(fēng)光,感受中國(guó)發(fā)生的巨大變化,某外文雜志社將出版一本英語(yǔ)小冊(cè)子來(lái)介紹中國(guó)的旅游景點(diǎn)。該雜志社邀請(qǐng)你為該小冊(cè)子寫一篇英語(yǔ)短文來(lái)介紹杭州,內(nèi)容包括:1.杭州的位置(中國(guó)東南部)、面積(16 000多平方公里)及歷史(2 200多年)等;2.杭州的旅游特色(自然風(fēng)景、傳統(tǒng)文化、特色小吃等);3.希望更多的游客來(lái)杭州參觀。注意:1.詞數(shù)80左右;2.可適當(dāng)增加細(xì)節(jié),以使行文連貫。Located in the southeast of China, Hangzhou is a beautiful city.Dating back more than 2,200 years, Hangzhou covers an area of more than 16,000 square kilometers.In Hangzhou, you can visit the West Lake, whose scenery is fascinating.In addition, you can’t miss its cultural relics and historical sites, from which you will learn more about excellent Chinese traditional culture and traditions.In Hangzhou, the special snacks are famous and visitors from different parts of the world think highly of them.As a tourist attraction, Hangzhou attracts a large number of visitors from home and abroad every year.Once you come to China, Hangzhou is a scenic spot you can’t miss.
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?yàn)閷懙么颐? 這篇文章不是很好。2. ________ carefully, he found something he hadn’t known before. 他仔細(xì)讀書時(shí), 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(dāng)被問(wèn)及他為什么要這么做時(shí), 班長(zhǎng)說(shuō)這是他的職責(zé)
choir memberspeople to run food stands people to sell festival ticketspeople to sell music CDspeople to set up equipmentmusical performersStep 2: Listen to the announcement again and answer the questions. ? 1. What kind of songs will Grace Davis sing at the festival?? 2. Who can try out as a performer?? 3. What can those who think they do not have musical talent do?? 4. How can students volunteer to take part?? Talking about preferences:? Would you prefer doing ..?? What would you prefer to do?? Would you rather do .... or ….?? What would you rather do?? I'd prefer .... to ..? I'd rather have ... than .. Step 3: Speaking ProjectWork in groups. Role-play the conversation or make a new one.? Debbie: Where have you been? You missed the announcement about the music festival.? John: I was at the doctor's office. Music festival?? Frank: Yes, it's going to be next month on the school sports field. John, you can play the piano. How about playing it at the festival?? John: Well, I'd rather play the violin. I can play Liang Zhu.? Frank: Wow! Sounds good. What about you, Debbie? ? Debbie: Actually, I don't have much musical ability. I'd prefer just to help out with the crowds.? Frank: You can sell tickets or work at a food stand.? John: So can I assume that the aim of the festival is to raise money?? Debbie: Yes. All of the money will go to charity.
Step1:自主探究。1.(教材P52)Born(bear) in the USA on 2 January 1970, Whitacre began studying music at the University of Nevada in 1988.2.(教材P52) Moved(move) by this music, he said, “It was like seeing color for the first time.”3.(教材P56)I was very afraid and I felt so alone and discouraged(discourage).4.(教材P58)Encouraged(encourage) by this first performance and the positive reaction of the audience, I have continued to play the piano and enjoy it more every day.Step2:語(yǔ)法要點(diǎn)精析。用法1:過(guò)去分詞作表語(yǔ)1).過(guò)去分詞可放在連系動(dòng)詞be, get, feel, remain, seem, look, become等之后作表語(yǔ),表示主語(yǔ)所處的狀態(tài)Tom was astonished to see a snake moving across the floor.湯姆很驚訝地看到一條蛇正爬過(guò)地板。Finally the baby felt tired of playing with those toys.終于嬰兒厭倦了玩那些玩具。注意:1).過(guò)去分詞作表語(yǔ)時(shí)與被動(dòng)語(yǔ)態(tài)的區(qū)別過(guò)去分詞作表語(yǔ)時(shí),強(qiáng)調(diào)主語(yǔ)所處的狀態(tài);而動(dòng)詞的被動(dòng)語(yǔ)態(tài)表示主語(yǔ)是動(dòng)作的承受者,強(qiáng)調(diào)動(dòng)作。The library is now closed.(狀態(tài))圖書館現(xiàn)在關(guān)閉了。The cup was broken by my little sister yesterday.(動(dòng)作)昨天我妹妹把杯子打碎了。2)感覺(jué)類及物動(dòng)詞的現(xiàn)在分詞與過(guò)去分詞作表語(yǔ)的區(qū)別過(guò)去分詞作表語(yǔ)多表示人自身的感受或事物自身的狀態(tài),常譯作“感到……的”;現(xiàn)在分詞多表示事物具有的特性,常譯作“令人……的”。
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.
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
知識(shí)和技能 ⑴從圖片和簡(jiǎn)易圖中,了解氣團(tuán)(冷氣團(tuán)、暖氣團(tuán))的概念;鋒的概念與分類;低壓(氣旋)、高壓(反氣旋)、高壓脊、低壓槽的概念。⑵從氣溫、氣壓、濕度、降水、風(fēng)等幾方面分析各種天氣系統(tǒng)的形成及其氣流特點(diǎn),并綜合出各種天氣系統(tǒng)控制下的天氣狀況過(guò)程與方法 ⑴讓學(xué)生能閱讀和簡(jiǎn)單分析天氣圖,解釋天氣變化現(xiàn)象;⑵用案例說(shuō)明氣象災(zāi)害發(fā)生的原因和危害;⑶結(jié)合我國(guó)常見(jiàn)的天氣系統(tǒng)說(shuō)明其對(duì)人們生產(chǎn)和生活的影響情感、態(tài)度與價(jià)值觀激發(fā)學(xué)生探究天氣的形成和變化的興趣和動(dòng)機(jī),培養(yǎng)學(xué)生求真、求實(shí)的科學(xué)態(tài)度,提高地理審美情趣教學(xué)重點(diǎn)1.鋒面系統(tǒng)。(鋒面系統(tǒng):一是要區(qū)別冷暖鋒的成因,二是要掌握鋒面兩側(cè)的氣壓、溫度、濕度、風(fēng)和天氣差異)2.低壓、高壓系統(tǒng)。(要掌握其成因、氣壓特征、氣流特征及其天氣特點(diǎn)四個(gè)方面。)
過(guò)渡:在實(shí)際生活中,城市內(nèi)部空間結(jié)構(gòu)并非完全按照這一經(jīng)濟(jì)規(guī)律呈現(xiàn),而是更具復(fù)雜性。這說(shuō)明除了經(jīng)濟(jì)因素外,還有很多其他因素在起作用,請(qǐng)大家結(jié)合你的認(rèn)識(shí)、圖2.9和案例1:紐約市的少數(shù)民族區(qū)談?wù)勀愕目捶ā#?)其他因素I收入——形成不同級(jí)別住宅區(qū)的常見(jiàn)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(jí)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(jì)方面具有很高的聲譽(yù),這往往會(huì)吸引更多新的住宅或商場(chǎng)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(gè)種族或宗教團(tuán)體占優(yōu)勢(shì),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(shè)計(jì)可以維持久遠(yuǎn),早期的土地利用方式對(duì)日后的功能分區(qū)有著深遠(yuǎn)的影響。
一般情況下,凡是支持物對(duì)物體的支持力,都是支持物因發(fā)生形變而對(duì)物體產(chǎn)生彈力。所以支持力的方向總是垂直于支持面而指向被支持的物體。例1:放在水平桌面上的書書由于重力的作用而壓迫桌面,使書和桌面同時(shí)發(fā)生微小形變,要恢復(fù)原狀,對(duì)桌面產(chǎn)生垂直于桌面向下的彈力f1,這就是書對(duì)桌面的壓力;桌面由于發(fā)生微小的形變,對(duì)書產(chǎn)生垂直于書面向上的彈力f2,這就是桌面對(duì)書的支持力。學(xué)生分析:靜止地放在傾斜木板上的書,書對(duì)木板的壓力和木板對(duì)書的支持力。并畫出力的示意圖。結(jié)論:壓力、支持力都是彈力。壓力的方向總是垂直于支持面而指向被壓的物體,支持力的方向總是垂直于支持面而指向被支持的物體。引導(dǎo)學(xué)生分析靜止時(shí),懸繩對(duì)重物的拉力及方向。引導(dǎo)得出:懸掛物由于重力的作用而拉緊懸繩,使重物、懸繩同時(shí)發(fā)生微小的形變。重物由于發(fā)生微小的形變,對(duì)懸繩產(chǎn)生豎直向下的彈力f1,這是物對(duì)繩的拉力;懸繩由于發(fā)生微小形變,對(duì)物產(chǎn)生豎直向上的彈力f2,這就是繩對(duì)物體的拉力。
l.知識(shí)與技能:(1)知道摩擦力產(chǎn)生的條件。(2)能在簡(jiǎn)單問(wèn)題中,根據(jù)物體的運(yùn)動(dòng)狀態(tài),判斷靜摩擦力的有無(wú)、大小和方向;知道存在著最大靜摩擦力。(3)掌握動(dòng)磨擦因數(shù),會(huì)在具體問(wèn)題中計(jì)算滑動(dòng)磨擦力,掌握判定摩擦力方向的方法。(4)知道影響到摩擦因數(shù)的因素。2.過(guò)程與方法:通過(guò)觀察演示實(shí)驗(yàn),概括出摩擦力產(chǎn)生的條件及摩擦力的特點(diǎn),培養(yǎng)學(xué)生的觀察、概括能力。通過(guò)靜摩擦力與滑動(dòng)摩擦力的區(qū)別對(duì)比,培養(yǎng)學(xué)生分析綜合能力。3.情感態(tài)度價(jià)值觀:在分析物體所受摩擦力時(shí),突出主要矛盾,忽略次要因素及無(wú)關(guān)因素,總結(jié)出摩擦力產(chǎn)生的條件和規(guī)律。二、重點(diǎn)、難點(diǎn)分析1.本節(jié)課的內(nèi)容分滑動(dòng)摩擦力和靜摩擦力兩部分。重點(diǎn)是摩擦力產(chǎn)生的條件、特性和規(guī)律,通過(guò)演示實(shí)驗(yàn)得出關(guān)系f=μN(yùn)。2.難點(diǎn)是學(xué)生有初中的知識(shí),往往誤認(rèn)為壓力N的大小總是跟滑動(dòng)物體所受的重力相等,因此必須指出只有當(dāng)兩物體的接觸面垂直,物體在水平拉力作用下,沿水平面滑動(dòng)時(shí),壓力N的大小才跟物體所受的重力相等。
1.用CAI課件模擬汽車的啟動(dòng)過(guò)程。師生共同討論:①如果作用在物體上的力為恒力,且物體以勻速運(yùn)動(dòng),則力對(duì)物體做功的功率保持不變。此情況下,任意一段時(shí)間內(nèi)的平均功率與任一瞬時(shí)的瞬時(shí)功率都是相同的。②很多動(dòng)力機(jī)器通常有一個(gè)額定功率,且通常使其在額定功率狀態(tài)工作(如汽車),根據(jù)P=FV可知:當(dāng)路面阻力較小時(shí),牽引力也小,速度大,即汽車可以跑得快些;當(dāng)路面阻力較大,或爬坡時(shí),需要比較大的牽引力,速度必須小。這就是爬坡時(shí)汽車換低速擋的道理。③如果動(dòng)力機(jī)器在實(shí)際功率小于額定功率的條件下工作,例如汽車剛剛起動(dòng)后的一段時(shí)間內(nèi),速度逐漸增大過(guò)程中,牽引力仍可增大,即F和v可以同時(shí)增大,但是這一情況應(yīng)以二者乘積等于額定功率為限度,即當(dāng)實(shí)際功率大于額定功率以后,這種情況不可能實(shí)現(xiàn)。
(五)平拋運(yùn)動(dòng)規(guī)律的應(yīng)用例1:一架老式飛機(jī)在高出海面45m的高處,以80m/s的速度水平飛行,為了使飛機(jī)上投下的炸彈落在停在海面上的敵船,應(yīng)該在與轟炸目標(biāo)的水平距離為多遠(yuǎn)的地方投彈?不計(jì)空氣阻力。分析:對(duì)于這道題我們可以從以下幾個(gè)方面來(lái)考慮:(1)從水平飛行的飛機(jī)上投下的炸彈,做什么運(yùn)動(dòng)?為什么?(2)炸彈的這種運(yùn)動(dòng)可分解為哪兩個(gè)什么樣的分運(yùn)動(dòng)?3)要想使炸彈投到指定的目標(biāo)處,你認(rèn)為炸彈落地前在水平方向通過(guò)的距離與投彈時(shí)飛機(jī)離目標(biāo)的水平距離之間有什么關(guān)系?拓展:1、式飛機(jī)在高出海面45m的高處,以80m/s的速度水平飛行,尾追一艘以15m/s逃逸的敵船,為了使飛機(jī)上投下的炸彈正好擊中敵船,應(yīng)該在與轟炸目標(biāo)的水平距離為多遠(yuǎn)的地方投彈?不計(jì)空氣阻力。2、在一次摩托車跨越壕溝的表演中,摩托車從壕溝的一側(cè)以速度v=40m/s沿水平方向向另一側(cè),壕溝兩側(cè)的高度及寬度如圖所示,摩托車可看做質(zhì)點(diǎn),不計(jì)空氣阻力。(1)判斷摩托車能否跨越壕溝?請(qǐng)計(jì)算說(shuō)明(2)若能跨過(guò),求落地速度?