题目内容
如图所示,在同一竖直面内,小球a、b从高度不同的两点,分别以初速度va和vb沿水平方向抛出,经过时间ta和tb后落到与两抛出点水平距离相等的P点.若不计空气阻力,下列关系式正确的是
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241245416851777.png)
A.ta>tb,va<vb | B.ta>tb,va>vb? | C.ta<tb,va<vb | D.ta<tb,va>vb |
A
由平抛规律知
。竖直方向
,所以
,水平位移相同,
,A对。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824124541717873.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824124541748521.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824124541779480.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824124541966470.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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