题目内容
物体静止在光滑水平面上,对物体施一水平向右的恒力F1,经过时间t突然撤去F1,立即对它施一水平向左的恒力F2,又经过时间t物体恰好到达出发点.则两段时间内
A.加速度a1和a2大小之比为1:2 |
B.最大速度![]() ![]() |
C.通过的位移x1和x2大小之比是1:3 |
D.F1、F2对该物体做功的最大即时功率之比是1:6 |
D
试题分析:设开始加速度为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824163037331314.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824163037940348.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824163038189942.png)
计算得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824163038439494.png)
刚撤去
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824163038720333.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824163039079472.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824163039344709.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824163038720333.png)
两力所对应位移大小相等,故C错误
功率最大对应速率最大,
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824163038720333.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824163040295353.png)
所以正确选项应该是D
点评:在
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824163038720333.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824163040295353.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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