题目内容
在高h处以初速度
将物体水平抛出,它们落地与抛出点的水平距离为s,落地时速度为
,由以上信息可求出物体从抛出到落地所经历的时间。下列有关此时间的表达式错误的是 ( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132534168328.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132534199305.png)
A.![]() | B.![]() | C.![]() ![]() | D.![]() |
C
由平抛运动的公式x= vo t,得t=![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132534230199.png)
y =
g t2得t=![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132534262260.png)
落地时速度为
为合速度
=
,
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132534652647.png)
vy=" g" t
t=![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132534402310.png)
所以C错。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132534230199.png)
y =
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132534449305.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132534262260.png)
落地时速度为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132534527291.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132534527291.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132534589638.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132534652647.png)
vy=" g" t
t=
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132534402310.png)
所以C错。
![](http://thumb2018.1010pic.com/images/loading.gif)
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