题目内容
物体做竖直上抛运动,取g=10m/s2。若第1s内位移大小恰等于所能上升的最大高度的
倍,求物体的初速度。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113821606235.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113821621221.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113821653224.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113821668225.gif)
常会有同学根据题意由基本规律列出形如
t-
gt2=
·
的方程来求解,实质上方程左端的
t-
gt2并不是题目中所说的“位移大小”,而只是“位移”,物理概念不清导致了错误的产生。
解:由题意有
=
·
,
进而解得
=30m/s,
=6m/s,
=4.45m/s
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113821684212.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113821699225.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113821606235.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113821731392.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113821684212.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113821699225.gif)
解:由题意有
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113821777564.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113821606235.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113821731392.gif)
进而解得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113821621221.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113821653224.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113821668225.gif)
![](http://thumb2018.1010pic.com/images/loading.gif)
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