1.定義:做圓周運(yùn)動的物體通過的弧長與所用時間的比值
1、描述勻速圓周運(yùn)動的有關(guān)物理量
(1)線速度
4、線速度與角速度的關(guān)系
線速度和角速度都能描述圓周運(yùn)動的快慢,它們之間有何關(guān)系呢?下面請同學(xué)們依據(jù)剛學(xué)過的線速度和角速度的概念和定義,推導(dǎo)出線速度和角速度的關(guān)系v=rω
點(diǎn)評:通過推導(dǎo),加深對所學(xué)知識的理解,掌握知識間的聯(lián)系.到此,教師還需引導(dǎo)學(xué)生進(jìn)一步思考;以上都能描述圓周運(yùn)動快慢的線速度、角速度、轉(zhuǎn)速和周期,除了有以上的聯(lián)系外,還有沒有不同的地方?如果學(xué)生通過討論發(fā)現(xiàn)周期這一概念更能突顯出圓周運(yùn)動的周期性和重復(fù)性,將使學(xué)生對圓周運(yùn)動有進(jìn)一步的認(rèn)識。
例題分析
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板書設(shè)計:
第五節(jié) 圓周運(yùn)動
請同學(xué)觀看兩個物體所做的曲線運(yùn)動,并請注意觀察它們的運(yùn)動特點(diǎn):
第一個:老師用事先準(zhǔn)備好的用細(xì)線拴住的小球,演示水平面內(nèi)的圓周運(yùn)動;
第二個:課件展示同學(xué)們熟悉的手表指針的走動.(它們的軌跡是一個圓)這就是我們今天要研究的圓周運(yùn)動。
第三節(jié) 書面表達(dá)(滿分30分)
假設(shè)你是李華。你在美國的朋友David給你發(fā)來一封電子郵件,詢問你在暑假期間除了做家庭作業(yè)以我,還進(jìn)行了什么有趣、有意義的活動。請你給他回一封電子郵件,向他介紹你在放假期間的主要活動。內(nèi)容要點(diǎn)如下:
1.和同學(xué)及朋友觀看世界杯足球賽。
2.上輔導(dǎo)課(學(xué)習(xí)數(shù)學(xué)、物理、化學(xué))
3.在餐館打工兩周,洗碗、洗菜。
4.到敬老院做義工(打掃衛(wèi)生、為老人讀報)
注意:
1)不要逐條翻譯,可適當(dāng)填加細(xì)節(jié),詞數(shù)100左右。開頭和結(jié)尾已給出,不計入總詞數(shù)。
2)可能用到的詞:輔導(dǎo)課:training course 義工:voluntary work 老年人:the elderly
敬老院:nursing home
Dear David,
Thanks for your e-mail. Now I’d like to tell you something about my summer vacation.
第二節(jié) 短文改錯(共10小題;每小題1.5分,滿分15分)
此題要求改正所給短文中的錯誤.對標(biāo)題號的每一行做出判斷:如無錯誤,在該行右邊的橫線上劃(√);如有錯誤(每行只有一個錯誤),則按下列情況改正:
此行多一個詞:把多余的詞用斜線劃掉,在該行右邊橫線上寫出該詞,并也用斜線劃掉。
此行缺一個詞:在缺詞處加一個漏字符號(^),在該行右邊橫線上寫出該加的詞。
此行錯一個詞:在錯的詞下劃一橫線,在該行右邊橫線上寫出改正后的詞。
注意:原行沒有錯的不要改。
I still remember on the first day when I came to college. 76.
It was a sunny day. Everything seems fresh to me. All the 77.
students were exciting. I was, too. I had long dreamed 78.
of becoming a college student. Years late, my dream 79.
had come true. This was really turning point in my life. I 80.
looked at the beautiful classroom buildings. I felt proud for my 81.
college. I knew that going to college would be a good chance 82.
to get a great deal of knowledges, which would be useful 83.
for your future career. Meanwhile I knew that studying at college 84.
was a great challenge to me. H had to learn what to overcome the 85.
difficulties in my study and life at college.
第一節(jié) 單詞拼寫(共10小題,每小題1分,滿分10分)
根據(jù)下列句子及所給漢語注釋,寫出空缺處各單詞的正確形式。(每空只寫一詞)
66.He looked at his garden with (驕傲). 66.
67.His father was asked to work in a (外國的)country. 67.
68.The old farmer had his land (分割)among his five sons. 68.
69.His birthday falls on the (第九)day of September. 69.
70.Fruit trees grow along protected hillsides and (山谷). 70.
71.The 2010 (青年)Olympic Games ended on August 26,2010. 71.
72.The mid-term examination always happens in (十一月). 72.
73.Take the medicine (定期地)three times a day. 73.
74.Before every concert, she worries about how well she will (表演). 74.
75.When he was young, he (更喜歡)not to think about the future. 75.
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