题目内容
如图所示,在平坦的垒球场上,击球手挥动球棒将垒球水平击出,垒球在空中飞行一段时间后落地。若不计空气阻力,则下列说法中正确的是
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408242207181812809.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408242207181812809.jpg)
A.垒球在空中运动过程中速度、加速度时刻改变 |
B.垒球落地时速度的方向可以竖直向下 |
C.垒球在空中运动的时间仅由击球点离地面的高度决定 |
D.垒球落地点与击球点的水平距离仅由初速度决定 |
C
试题分析:垒球水平击出为平抛运动。水平方向不受力为匀速直线运动
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824220718493420.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824220719741518.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824220721613544.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824220722924646.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824220723719961.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824220722924646.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824220725669672.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824220726621974.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408242207271982320.jpg)
![](http://thumb2018.1010pic.com/images/loading.gif)
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