题目内容
一汽车在高速公路上以
=30m/s的速度匀速行驶,t=0时刻,驾驶员采取某种措施,车运动的加速度随时间变化关系如图所示,以初速度方向为正,下列说法正确的是
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250038322963529.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003832280323.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250038322963529.jpg)
A.t=6s时车速为5m/s |
B.t=3s时车速为零 |
C.前9s内的平均速度为15m/s |
D.前6s内车的位移为90m |
BC
试题分析:前三秒中,初速度为正,加速度为负,汽车做匀减速直线运动,速度
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250038323121091.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003832327964.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003832343449.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003832358981.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003832390430.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003832405994.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003832421593.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003832452432.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250038324681147.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003832483456.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250038324991166.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003832530821.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250038325461240.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003832577797.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003832592886.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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