题目内容
跳伞运动员从某高度的直升机上跳下,经过2s拉开绳索开启降落伞,此后再过18s落地。整个跳伞过程中的
-t图象如图所示。根据图象信息可知( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250031372739961.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003137242276.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250031372739961.png)
A.4s末速度为16m/s |
B.14s末加速度为零 |
C.前2s跳伞运动员的机械能守恒 |
D.跳伞运动员下落的总高度约为240m |
B
试题分析:由图知4s末的速度为18m/s,故A错误;根据
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003137242276.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003137242276.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003137242276.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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