题目内容
一辆汽车在平直的公路上行驶,刹车后它的位移与时间的关系x=24t–3t2,以下说法正确的有
A.汽车在做减速运动,运动的加速度大小为3m/s2 |
B.第1s末物体的速度为18m/s |
C.t =5s时汽车的位移为45m |
D.汽车在最初2s内的平均速度为18m/s |
BCD
试题分析:将x=24t–3t2对照
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002423514781.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002423530486.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002423545402.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002423561688.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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