
1.導(dǎo)入新課:用觸目精心的一首MTV《EARTHSONG》導(dǎo)入新課,引出人類已經(jīng)面臨嚴(yán)峻的人口、資源與環(huán)境的危機(jī)。而中國是世界上人口最龐大的國家,人口、資源與環(huán)境問題更加嚴(yán)重。既然我們知道了可持續(xù)發(fā)展的概況,了解了它的發(fā)展過程,從上節(jié)課內(nèi)容的分析中,也理解了作為人類的發(fā)展,可持續(xù)是唯一的選擇,也是我們所追求的目標(biāo),那么,具體到我們國家、我們周圍的生產(chǎn)、生活情況又該如何呢?2.新課講授:首先,通過三則補(bǔ)充材料的案例和課本上的內(nèi)容分別說明龐大的人口壓力,資源短缺和不合理利用,深刻的環(huán)境危機(jī)方面的問題,得出走可持續(xù)發(fā)展之路是我國的必然的唯一的選擇。接著通過《中國21世紀(jì)議程》——中國21世紀(jì)人口環(huán)境與發(fā)展的白皮書的過渡引出實施可持續(xù)發(fā)展的途徑。在這部分內(nèi)容的講解上,主要通過其中一種主要途徑-循環(huán)經(jīng)濟(jì)的講解,特別是對清潔生產(chǎn)和生態(tài)農(nóng)業(yè)的具體分析,總結(jié)出中國走可持續(xù)發(fā)展之路事在必行,行必有果。再通過完成課本上最后一個活動題對本節(jié)內(nèi)容進(jìn)行深化。

環(huán)節(jié)四 課堂小結(jié) 鞏固知識本節(jié)課我采用線索性的板書,整個知識結(jié)構(gòu)一目了然,為了充分發(fā)揮學(xué)生在課堂的主體地位,我將課堂小結(jié)交由學(xué)生完成,請學(xué)生根據(jù)課堂學(xué)習(xí)的內(nèi)容,結(jié)合我的板書設(shè)計來進(jìn)行小結(jié),以此來幫助教師在第一時間掌握學(xué)生學(xué)習(xí)信息的反饋,同時培養(yǎng)學(xué)生歸納分析能力、概括能力。環(huán)節(jié)五 情景回歸,情感升華我的實習(xí)指導(dǎo)老師告訴過我們,政治這一門學(xué)科要從生活中來到生活去,所以在課堂的最后布置課外作業(yè),以此培養(yǎng)學(xué)生對理論的實際運(yùn)用能力,同時檢驗他們對知識的真正掌握情況,以此達(dá)到情感的升華,本節(jié)課,我根據(jù)建構(gòu)主義理論,強(qiáng)調(diào)學(xué)生是學(xué)習(xí)的中心,學(xué)生是知識意義的主動建構(gòu)者,是信息加工的主體,要強(qiáng)調(diào)學(xué)生在課堂中的參與性、以及探究性,不僅讓他們懂得知識,更讓他們相信知識,并且將知識融入到實踐當(dāng)中去,最終達(dá)到知、情、意、行的統(tǒng)一。

蘇聯(lián)文學(xué)的沿革,既反映了蘇聯(lián)社會的偉大思想性變革,又反映了蘇聯(lián)文壇活躍與混亂并存的局面,特別是其所具有強(qiáng)烈的意識形態(tài)色彩是蘇聯(lián)社會深層次變化的風(fēng)向標(biāo)。(2)20世紀(jì)的亞、非、拉美文學(xué)20世紀(jì)亞、非、拉美文學(xué)的繁榮伴隨著民族民主運(yùn)動的高漲,其主流都體現(xiàn)了反對殖民壓迫、反對社會不公的愛國主義精神。出現(xiàn)了許多頗有影響的作家和作品。泰戈爾是印度近現(xiàn)代文學(xué)的光輝代表,為印度現(xiàn)代民族主義奠定了基礎(chǔ)。其代表作《戈拉》塑造了愛國的印度民族主義知識分子形象。泰戈爾是首位獲諾貝爾文學(xué)獎的東方作家。魯迅是中國文學(xué)革命的巨匠,他的《吶喊》集,昭示著中國新文學(xué)時代的到來。哥倫比亞作家馬爾克斯的《百年孤獨》,描繪加勒比海沿岸小城百年孤獨的原因及打破這種狀態(tài)的途徑。

畫中的諸多圖像反映了畫家對于傳統(tǒng)繪畫因素的吸收。那個懷抱死去孩子的母親圖像,似乎是源自哀悼基督的圣母像傳統(tǒng);手持油燈的女人,使人聯(lián)想起自由女神像的造型;那個高舉雙手仰天驚呼的形象,與戈雅畫中愛國者就義的身姿不無相似之處;而那個張臂倒地的士兵形象,則似乎與意大利文藝復(fù)興早期某些戰(zhàn)爭畫中的形象,有著姻親關(guān)系。由此可以看出,畢加索不僅是一位富于叛逆精神的大膽創(chuàng)新者,同時也是一位尊崇和精通傳統(tǒng)的藝術(shù)家。教師須強(qiáng)調(diào):現(xiàn)代主義美術(shù)是現(xiàn)代美術(shù)流派的總稱,現(xiàn)代美術(shù)流派眾多,多姿多彩,但它們也表現(xiàn)出許多共同的特征。在技法上,它們大都反對傳統(tǒng)的寫實主義,追求新奇,空間結(jié)構(gòu)錯亂,色彩配置隨意,點線紊亂,缺乏透視可謂它們共有的特點。在創(chuàng)作主旨上,它們都主張強(qiáng)調(diào)自我,表現(xiàn)個人情感和內(nèi)心世界??梢哉f,現(xiàn)代美術(shù)藝術(shù)再現(xiàn)了20世紀(jì)西方世界的精神狀況。

教學(xué)目標(biāo):1、知識與能力:(1)識記:理性、啟蒙運(yùn)動;伏爾泰、孟德斯鳩、盧梭等偉大的啟蒙思想家及其主張;康德及啟蒙運(yùn)動的影響;(2)理解啟蒙運(yùn)動興起的背景,分析啟蒙思想的巨大影響;(3)認(rèn)識上層建筑對社會發(fā)展的巨大反作用。2、過程與方法:(1)指導(dǎo)學(xué)生用表格法掌握啟蒙運(yùn)動主要代表人物及其思想主張;(2)運(yùn)用比較法加深對啟蒙思想家觀點共性和個性的認(rèn)識。(3)運(yùn)用比較法對比文藝復(fù)興和啟蒙運(yùn)動的異同,說明啟蒙運(yùn)動對人文主義思想的發(fā)展。3、情感態(tài)度與價值觀:(1)通過本課的學(xué)習(xí),讓學(xué)生認(rèn)識到“一定的文化是一定社會的政治和經(jīng)濟(jì)在觀念上和形態(tài)上的反映”;(2)學(xué)習(xí)啟蒙思想家追求真理的精神,培養(yǎng)學(xué)生遠(yuǎn)大的理想與抱負(fù);(3)通過法國啟蒙思想產(chǎn)生的巨大影響的分析,使學(xué)生認(rèn)識意識形態(tài)對社會發(fā)展所起的重大作用,從而提高學(xué)習(xí)理論的自覺性。

二、程朱理學(xué):1、宋代“理學(xué)”的產(chǎn)生:(1)含義:所謂“理學(xué)”,就是用“理學(xué)”一詞來指明當(dāng)時兩宋時期所呈現(xiàn)出來的儒學(xué)。廣義的理學(xué),泛指以討論天道問題為中心的整個哲學(xué)思潮,包括各種不同的學(xué)派;狹義的理學(xué),專指程顥、程頤、朱熹為代表的,以“理”為最高范疇的學(xué)說,稱為“程朱理學(xué)”。理學(xué)是北宋政治、社會、經(jīng)濟(jì)發(fā)展的理論表現(xiàn),是中國古代哲學(xué)長期發(fā)展的結(jié)果,是批判佛、道學(xué)說的產(chǎn)物。他們把“理”或“天理”視作哲學(xué)的最高范疇,認(rèn)為理無所不在,不生不滅,不僅是世界的本原,也是社會生活的最高準(zhǔn)則。在窮理方法上,程顥“主靜”,強(qiáng)調(diào)“正心誠意”;程頤“主敬”,強(qiáng)調(diào)“格物致知”。在人性論上,二程主張“去人欲,存天理”,并深入闡釋這一觀點使之更加系統(tǒng)化。二程學(xué)說的出現(xiàn),標(biāo)志著宋代“理學(xué)”思想體系的正式形成?!竞献魈骄俊克未袄韺W(xué)”興起的社會條件:

This teaching period mainly deals with grammar “The Present Perfect Passive Voice.” To begin with, teachers should lead students to revise what they have learned about the Present Perfect Passive Voice. And then, teachers move on to stress more special cases concerning this grammar。This period carries considerable significance to the cultivation of students’ writing competence and lays a solid foundation for the basic appreciation of language beauty. The teacher is expected to enable students to master this period thoroughly and consolidate the knowledge by doing some exercises. 1. Guide students to review the basic usages of the Present Perfect Passive Voice2. Lead students to learn to use some special cases concerning the Present Perfect Passive Voice flexibly.2. Enable students to use the basic phrases structures flexibly.3. Strengthen students’ great interest in grammar learning.1. Help students to appreciate the function of the Present Perfect Passive Voice in a sentence2. Instruct students to write essays using the proper the Present Perfect Passive Voice.觀察下列句子特點,總結(jié)共同點。1.(教材P28)Much has been written about the wonders of the World Wide Web.2.(教材P28)But the Internet has done much more for people than simply make life more convenient.3.(教材P28)Many people have been helped by the club.4.(教材P28)She no longer feels lonely, and her company has become quite successful.5.(教材P32)Today I thought I’d blog about a question that has been asked many times—how do you stay safe online and avoid bad experiences on the Internet?

This unit is about the Internet, which has a great influence to our humans and our lives. During the Listening & Speaking & Talking and Reading and Thinking section, the influence in examples has been shown. Thus, use the Present Perfect Tense is appropriate. However, in order to show the justice or weaken the doer of the behavior/action, it’s better to use the Present Perfect Passive Voice than the Present Perfect Tense. Besides, having learned to use the Present Perfect Passive Voice, students can beautify their language in their writing. 1. Learn the structure of the Present Perfect Passive Voice and its functions. 2. Learn to change the sentences with the Present Perfect Passive Voice into the sentences with the Present Perfect Passive Voice. 3. Learn to write sentences with the Present Perfect Passive Voice flexibly according to the context. 1. Learn the structure of the Present Perfect Passive Voice and its functions. 2. Learn to change the sentences with the Present Perfect Passive Voice into the sentences with the Present Perfect Passive Voice. 3. Learn to write sentences with the Present Perfect Passive Voice flexibly according to the context. Step 1 Observe the following sentences, then change the sentences into passive voice.He has been selected to take part in the sports meeting.(肯定句)他已被挑選出來參加運(yùn)動會。The ink has not been removed from his overcoat.(否定句)墨跡還沒有從他外套上去掉。

From the pictures in the text and the title--- choose the best app, we can know that this part is about how to save money by using apps.Step 2 While-listening1. Laura and Xiao Bo are talking about apps. Listen to their conversation and find out what apps they want.Xiao Bo is looking for a(n) exercise app to help him get in shape.Laura would like an app for getting rich and another that will make her grades better.2. Listen again. Are the sentences true T or false F?1). Both of Xiao Bo's apps keep track of the steps he takes._____2). Xiao Bo's second app can help him make a fitness plan._____3). Laura needs an app that will help her get discounts.______4). Laura needs an app that will add money to her bank account._______F T F T3. Listen once more and tick the sentence you hear. Underline the words used to express predictions, guesses, and beliefs.Predictions, Guesses, and Beliefs________It might help me walk more.________My guess is that it wouldn't work.________I imagine this app would help me get fit faster________I suppose that would be good.________I guess you could save a little with this app.________I suppose there would be some problems, too.________I believe this app could help me get thinner.

⑦identity theft 身份盜竊⑧chat room 聊天室⑨draft your blog post 起草博客帖子⑩post embarrassing photos 張貼尷尬照片 【話題句式】 1. How do you stay safe online and avoid bad experiences on the Internet? 你如何在網(wǎng)上保持安全, 避免在網(wǎng)上的不良經(jīng)歷? 2. I’m not an expert, but many years as a blogger have taught me a thing or two. 我不是專家, 但作為一個博主, 我已經(jīng)學(xué)了好幾年了。 3. If you see or read something that makes you feel uncomfortable, leave the site immediately. 如果你看到或讀到一些讓你覺得不舒服的東西, 立即離開這個網(wǎng)站。4. Don’t give out your address or phone number. 別告訴別人你的地址或電話號碼。 5. Identity theft is a common and serious problem. 身份盜竊是一個常見而嚴(yán)重的問題。6. Being online is no excuse for being rude, and you don’t want to become a target for a troll or cyberbully. 上網(wǎng)并不是無禮的借口, 你也不想成為發(fā)挑釁帖子的人或網(wǎng)絡(luò)惡霸的目標(biāo)。 7. Trolls often use several false names so that they can stay on a site. 發(fā)挑釁帖子的人經(jīng)常使用幾個假名, 這樣他們就可以留在一個網(wǎng)站上。8. However, the more polite you are, the less likely it is you will be attacked. 然而, 你越有禮貌, 你被攻擊的可能性就越小。

Activity 41. Students complete the task of activity 4, then teachers and students check the answers. 2. The teacher organized the students to work together and asked them to use the tables and mind maps sorted out before to retold the important choices in Lin Qiaozhi's life and their resultsStep 5 Language points1. The teacher asks the students to read the text carefully, find out the core words and long and difficult sentences in the text and draw lines, understand the use of vocabulary, and analyze the structure of long and difficult sentences. 2. The teacher explains and summarizes the usage of core vocabulary and asks the students to take notes. 3. The teacher analyzes and explains the long and difficult sentences that the students don't understand, so that the students can understand them better. Step 6 Homework1. Read the text again, in-depth understanding of the text; 2. Master the use of core vocabulary and understand the long and difficult sentences. 3. Complete relevant exercises in the guide plan. 1、通過本節(jié)內(nèi)容學(xué)習(xí),學(xué)生是否理解和掌握閱讀文本中的新詞匯的意義與用法;2、通過本節(jié)內(nèi)容學(xué)習(xí),學(xué)生能否結(jié)合文本特點總結(jié)林巧稚的人生原則和人格品質(zhì)特征;3、通過本節(jié)內(nèi)容學(xué)習(xí),學(xué)生能否針對人生抉擇發(fā)表自己的看法;能否全面地、客觀地、理性地看待問題,進(jìn)而對道德和人性有更加深入的思考和理解。

The joke set her crying.這個玩笑使她哭起來。Step 5 ReadingActivity 31. Students read the small text in activity 3. The teacher provides several small questions to check whether students understand the content of the text and the ideographic function of the -ing form in the text.*Where are those people?*Why did Dr Bethune come to China?*How did he help the Chinese people during the war?*What did Chairman Mao Zedong say about him?2. Ss try to rewrite some sentences using the -ing form. Then check the answers. When checking the answers, the teacher can ask different students to read the rewritten sentences and give comments.Answers:1. he became very interested in medicine, deciding to become a doctor.2. …after hearing that many people were dying in the war.3. Helping to organise hospitals, he taught doctors and nurses, and showed people how to give first aid./ He helped to organise hospitals, teaching doctors and nurses, and showing people how to give first aid.4. …praising Dr Bethune as a hero to be remembered in China.Step 6 PracticeActivity 4Students complete grammar activities 2 and 3 on page 69 of the workbook.Step 6 Homework1. Understand and master the functions and usage of the -ing form;2. Finish the other exercises in Using structures.1、通過本節(jié)內(nèi)容學(xué)習(xí),學(xué)生是否理解和掌握動詞-ing形式作賓語補(bǔ)足語語和狀語語的功能和意義;2、通過本節(jié)內(nèi)容學(xué)習(xí),學(xué)生能否正確使用動詞-ing形式描述人物的行為、動作及其經(jīng)歷;3、通過本節(jié)內(nèi)容學(xué)習(xí),學(xué)生能否獨立完成練習(xí)冊和導(dǎo)學(xué)案中的相關(guān)練習(xí)。

3.Teachers ask different groups to report the answers to the questions and ask them to try different sentence patterns.The teacher added some sentence patterns for students to refer to when writing.Step 4 Writing taskActivity 51.Write the first draft.Students first review the evaluation criteria in activity 5, and then independently complete the draft according to the outline of activity 4, the answers to the questions listed in the group discussion and report, and the reference sentence pattern.2.Change partners.The teacher guides the students to evaluate their partner's composition according to the checklist of activity 5 and proposes Suggestions for modification.3.Finalize the draft.Based on the peer evaluation, students revise their own compositions and determine the final draft.Finally, through group recommendation, the teacher selects excellent compositions for projection display or reading aloud in class, and gives comments and Suggestions.Step 5 Showing writingActivity 5T call some Ss to share their writing.Step 6 Homework1. Read the passage in this section to better understand the passage.2. Carefully understand the hierarchical structure of the article, and deeply understand the plot of the story according to the causes, process and results;3. Independently complete the relevant exercises in the guide plan.1、通過本節(jié)內(nèi)容學(xué)習(xí),學(xué)生是否理解和掌握閱讀文本中的新詞匯的意義與用法;2、通過本節(jié)內(nèi)容學(xué)習(xí),學(xué)生能否通過人物言行的對比分析道德故事的深層內(nèi)涵;3、通過本節(jié)內(nèi)容學(xué)習(xí),學(xué)生能否根據(jù)故事的起因、經(jīng)過和結(jié)果來深入理解故事的情節(jié),從而了解文章的層次結(jié)構(gòu);4、結(jié)合現(xiàn)實生活案例發(fā)表自己的見解和看法,寫一篇觀點明確、層次分明的故事評論。

(2) students are divided into groups according to the requirements of activity 3. Each student shares a story of personal experience or hearing-witnessing kindness, and then selects the most touching story in the group and shares it with the whole class. Before the students share the story, the teacher can instruct them to use the words and sentence patterns in the box to express. For example, the words in the box can be classified:Time order: first of all, then, after that, later, finally logical relationship :so, however, although, butTeachers can also appropriately add some transitional language to enrich students' expression:Afterwards, afterwards, at last, in the end, eventuallySpatial order: next to, far from, on the left, in front ofOtherwise, nevertheless, as a result, therefore, furthermore, in addition, as well asSummary: in a word, in short, on the whole, to sum up, in briefStep 8 Homework1. Understand the definition of "moral dilemma" and establish a correct moral view;2. Accumulate vocabulary about attitudes and emotions in listening texts and use them to express your own views;3. Complete relevant exercises in the guide plan.1、通過本節(jié)內(nèi)容學(xué)習(xí),學(xué)生能否理解理解“道德困境”的定義;2、通過本節(jié)內(nèi)容學(xué)習(xí),學(xué)生能否通過說話人所表達(dá)的內(nèi)容、說話的語氣、語調(diào)等來判斷其態(tài)度和情緒;3、通過本節(jié)內(nèi)容學(xué)習(xí),學(xué)生能否針對具體的道德困境發(fā)表自己的看法和見解,能否掌握聽力理訓(xùn)練中的聽力策略。

Listening and Speaking introduces the topic of “ask about online habits”. Many middle school students have been surfing the Internet for many years, but what they do with the Internet and how much time they spend every day may not be very clear to themselves, nor to other students. This section allows students to investigate their peers' Internet use, which is conducive to their mutual understanding and understanding of the Internet. It can also help them reflect on their own online behavior, learn from other people's good online habits, and get rid of their bad online behavior.The listening text of this section is an investigation interview. The investigators interview specific groups with the same questions to obtain information, so as to understand their views, practices or attitudes on this issue. There are two specific questions: “how much time do you spend online every day? What do you usually do online?”. The answers of the three respondents provide rich and different information, and achieve the purpose of the investigators. The oral discourse structure of survey interviews generally includes greeting and explaining the purpose of the interview, presenting the interview questions and the respondents' answers. Listening and Talking introduces the theme of “choosing the right application ". Listening text is a conversation between Laura and Xiao Bo. In this part of listening, “oink”; “piggy bank” may cause the students' hearing comprehension limitation. Oink refers to sound word and pig's sound. So, add some oink to my piggy bank is often used to describe "making a little money".1. Guide students to understand the content of listening texts in terms of listening for definitions.2. Cultivate students' ability to define words and understand an investigation interview.

Q5:What's Jan's next goal?Her next goal is to start a charity website to raise money for children in poor countries.Q6:What can we learn from her experiences?We learn that when we go through tough times, we can find help and support from other people online. We learn that we can feel less lonelyStep 5: While reading---rethinkingQ1: What is Jan’s attitude to the Internet ?Thankful/Grateful, because it has changed her and her life.Q2: What writing skills is used in the article ?Examples(Jan’s example, the 59-year-old man’s and the 61-year-old woman’s example)Q3: Can you get the main idea of the article ?The Internet has changed Jan’s life/Jan’s life has been changed by the Internet.Step 6 Post reading---Retell the storyMuch has been written about the wonders of the World Wide Web. There are countless articles (1)telling(tell) us how the Internet has made our lives more convenient. But the Internet has done a lot (2)more(much) for people than simply make life more convenient. People’s lives (3) have been changed(change) by online communities and social networks so far. Take Jan for example, who developed a serious illness that made her (4)stuck(stick) at home with only her computer to keep (5)her(she) company. She joined an online group (6)where she could share problems, support and advice with others. She considered the ability to remove the distance between people as one of the greatest (7)benefits(benefit). She was so inspired (8)that she started an IT club in which many people have been helped. She has started to learn more about how to use the Internet to make society better. Her next goal is to start a charity website to raise money (9)for children in poor countries. Jan’s life has been (10)greatly(great) improved by the Internet.

Paragraph 3. Jan decided to start an IT club to teach old people how to use computers and the Internet. Paragraph 4. Jan has started taking online classes to learn more about how to use the Internet to make society better. Paragraph 5. Jan’s life has been greatly improved by the Internet. Step 5: Critical thinking:(1)How do you arrange your time spent on study and the Internet? Is it reasonable? I usually surf the Internet using my mobile phone for only an hour after class, and it is reasonable for me.(2)What are your online activities? Are they safe? I chat with my friends, read news and play games. I never give away my private information so I think they are safe.Step 4: summary Much has been written about the wonders of the World Wide Web. There are countless articles (1)______(tell) us how the Internet has made our lives more convenient. But the Internet has done a lot (2)_____(much) for people than simply make life more convenient. People’s lives (3) _________________(change) by online communities and social networks so far. Take Jan for example, who developed a serious illness that made her (4)_____(stick) at home with only her computer to keep (5)___(she) company. She joined an online group (6)______ she could share problems, support and advice with others. She considered the ability to remove the distance between people as one of the greatest (7)_______(benefit). She was so inspired (8)____ she started an IT club in which many people have been helped. She has started to learn more about how to use the Internet to make society better. Her next goal is to start a charity website to raise money (9)___ children in poor countries. Jan’s life has been (10)______(great) improved by the Internet. Step 5 Homework:Review what we have learned and find out the key language points in the text.

8. However, the more polite you are, the less likely it is you will be attacked. 然而, 你越有禮貌, 你被攻擊的可能性就越小。 Step 8 Writing---the articleHow to stay safe in the online chat roomToday I thought I’d blog about a question that has been asked many times--- how do you stay safe online and avoid bad experiences in the online chat room ? I’m not an expert, but many years as a blogger have taught me a thing or two.First of all, there’s the golden rule of the Internet: keep out of what makes you uneasy. Don’t post comments or click on anything. Second, protect your privacy. Don’t give out too much private information like your address, phone numbers, the ID numbers, etc. Third, be polite. If you are polite to others on the Internet, you won’t be attacked in normal situation. Finally, don’t believe in others easily and never meet someone you met online alone. It is very dangerous.Have you had any bad experiences online, or do you have some good advice for staying safe? Post your comments below!Step 9 Pair workExchange drafts with a partner. Use this checklist to help your partner revise his/her draft.1. Does the writer tell the reader what he/she know about the topic ?2. Are the tips and suggestions well organised ?3. Has the writer defined the new words ?4. Does the author include examples, comparison, or explanations ?5. Does the writer end by asking readers to leave comments and/or suggestions ?6. Can you find any grammar or spelling mistakes.Step 6 HomeworkPut up your revised draft in the classroom or read it to your class.

1.用CAI課件模擬汽車的啟動過程。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,則力對物體做功的功率保持不變。此情況下,任意一段時間內(nèi)的平均功率與任一瞬時的瞬時功率都是相同的。②很多動力機(jī)器通常有一個額定功率,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,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,需要比較大的牽引力,速度必須小。這就是爬坡時汽車換低速擋的道理。③如果動力機(jī)器在實際功率小于額定功率的條件下工作,例如汽車剛剛起動后的一段時間內(nèi),速度逐漸增大過程中,牽引力仍可增大,即F和v可以同時增大,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)實際功率大于額定功率以后,這種情況不可能實現(xiàn)。

(五)平拋運(yùn)動規(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?不計空氣阻力。分析:對于這道題我們可以從以下幾個方面來考慮:(1)從水平飛行的飛機(jī)上投下的炸彈,做什么運(yùn)動?為什么?(2)炸彈的這種運(yùn)動可分解為哪兩個什么樣的分運(yùn)動?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的距離與投彈時飛機(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,不計空氣阻力。(1)判斷摩托車能否跨越壕溝?請計算說明(2)若能跨過,求落地速度?
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