【題目】2016年6月25日20時00分07秒，長征七號運(yùn)載火箭從海南文昌航天發(fā)射中心首次發(fā)射，成功將載荷送入預(yù)定軌道，任務(wù)取得圓滿成功。如圖所示，長征七號多級火箭發(fā)射時，第一級火箭點(diǎn)火后，使衛(wèi)星向上勻加速運(yùn)動的加速度為50 m/s2，燃燒30 s后第一級脫離，第二級火箭沒有馬上點(diǎn)火，所以衛(wèi)星向上做加速度為10 m/s2的勻減速運(yùn)動，10 s后第二級火箭啟動，衛(wèi)星向上的加速度為80 m/s2，這樣經(jīng)過1分半鐘第二級火箭脫離時，衛(wèi)星的速度多大？
請你用v-t圖象描述這一過程。
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刪除：把多余的詞用斜線(＼)劃掉。
修改：在錯的詞下畫一橫線，并在該詞下面寫出修改后的詞。
注意：
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Which is known to all, nowadays the Internet is playing more and more important part in our daily life. In it, we can not only read news at home and abroad but also get so much information as possible. We are often send e-mails to our classmates. We can make telephone call to our families as well as our friends. However, we can go to school on the net, read different kinds of books and even teach myself English. We can also enjoy music, watching sports and play computer games on the Net. We could do shopping even without leaving our homes.
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注意：
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