一辆公共汽车进站后开始刹车，做匀减速直线运动。开始刹车后的第1 s内和第2 s内位移大小依次为9 m和7 m。则刹车后6 s内的位移是多少？
解：如图，设AB为X1 ，BC为X2，所用时间均为t=1s，则：
X1=VAt－
①
X1+X2=VA2t－
②
由①②得：VA=10m/s，a=2m/s2
所以：汽车行驶最长时间tm=
所以：刹车6s内的位移是：X=
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| The car, running along the welllit road now sank in darkness. I broke the 1 on purpose, 2 that the driver was too tired to drive. "When do you go back home in the evening?" "9 o'clock after this 3 ." "Then when do you come out in the morning?" I 4 another question. "9 o'clock, too-just as if I worked at an office." His 5 surprised me, because every time I ride a taxi, what I 6 from the driver are only complaints that they have to work from morning till night, it's hard to earn money, they're often 7 by the police, or that their leaders are seated lazily, 8 the fruits. But this driver told me, "I find it 9 to be a section chief as I was before. I like driving just for 10 . It's fortunate that I hardly drive 11 a passenger. So I earn two or three thousand yuan a month with ease. Yes, I never 12 an empty taxi. If it goes southward, I go northward. If it goes along a 13 , I turn into a narrow street..." His words showed his 14 with his life and the pride he 15 in his job. Such feelings are so rare among people nowadays as oxygen in high 16 . As an ancient saying goes, "Neither joy in material 17 nor grieve (悲痛) over personal setbacks." How many people nowadays can show high ideals by 18 living and go far with a calm mind? I couldn't help feeling 19 when finding such a state of mind in a stranger on a cold 20 . | ||||
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