题目内容
小球从空中自由下落,与水平地面相碰后弹到空中某一高度,其速度—时间图象如图所示,则由图可知(g取10 m/s2) ( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250019046963374.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250019046963374.jpg)
A.小球下落的高度2.5 m |
B.小球在从开始下落0.8 s内的平均速度大小是4 m/s,方向竖直向下 |
C.小球在从开始下落0.8 s内的位移为0.8 m,方向竖直向下 |
D.小球在从开始下落0.5 s内和后0.3 s内加速度大小相等,方向相同 |
CD
试题分析:据题意,小球经过0.5s落到地上,则下落高度为:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001904712887.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001904743962.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250019047591127.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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