题目内容
一枚子弹被以40 m/s的速度从地面竖直向上射出(忽略空气阻力,g=10m/s2),则
A.4s末到最高点 |
B.3s末、5s末的速度相同 |
C.它能到达的最大高度为80m |
D.它在空中运动过程中的平均速度为20m/s |
AC
试题分析:规定向上为正方向,子弹做初速度为
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001651098675.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001651113679.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001651129527.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001651145390.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001651176797.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001651176745.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001651191652.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001651207535.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250016512381008.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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