题目内容
将一小球竖直上抛,如果小球到达最高点前的最后一秒和离开最高点后的第一秒时间内通过的路分别为x1和x2,速度变化量的大小分别为
v1和
v2,假设小球所受空气阻力大小不变,则下列表述正确的是
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001950514319.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001950514319.png)
A.![]() ![]() ![]() ![]() |
B.![]() ![]() ![]() ![]() |
C.![]() ![]() ![]() ![]() |
D.![]() ![]() ![]() ![]() |
D
试题分析:竖直上抛运动小球受合力F1竖直向下,设空气阻力为f,则:F1=G+f 小球到达最高点前的最后一秒的加速度大小为:a1=
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001950888471.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001950904538.png)
△v1=a11 同理,下降过程合力F2=G-f,a2=
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001950919490.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001950935543.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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