题目内容
从高处以速度V0水平抛出一物体,要使物体有最大的水平距离,应选取下列数据中的哪一组:( )
A.h=10m,V0=5m/s | B.h=5m,V0=10m/s |
C.h=20m,V0=2.5m/s | D.h=2.5m,V0=20m/s |
D
影响平抛运动的水平位移的因素,主要有两个:物体与落点间的相对高度和水平的初速度.高度越大,速度越快,则水平位移越大。
当
时,运动时间为
,则水平位移为![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121158471779.png)
当
时,运动时间为
,则水平位移为![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121158627657.png)
当
时,运动时间为
,则水平位移为![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121158752648.png)
当
时,运动时间为
,则水平位移为![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121158845793.png)
可见
最大,故正确答案为D
当
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121158393716.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121158424909.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121158471779.png)
当
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121158502710.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121158533818.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121158627657.png)
当
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121158705770.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121158721892.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121158752648.png)
当
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121158799762.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121158814930.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121158845793.png)
可见
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121158877665.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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