题目内容
滑块以某一初速度冲上斜面做匀减速直线运动,到达斜面顶端时的速度恰为零,已知滑块通过斜面中点时的速度为v,则滑块在前一半路程中的平均速度大小为( )
A.![]() | B.(![]() | C.![]() | D.![]() |
A
本题考查的是灵活应用匀变速直线运动的规律的能力,根据题意画出运动过程示意图,如图,设斜面总长为2s,在斜面底端时,物体的速度为v0,加速度的大小为a,则根据匀变速运动速度位移关系vt2-v02=2as,得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241433133113593.jpg)
由A→C的过程-v02=-2a·2s
由B→C的过程-v2=-2a·s
所以v02=2v2,v0=
v
再根据
=
,得前一半路程中
=![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824143313498930.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241433133113593.jpg)
由A→C的过程-v02=-2a·2s
由B→C的过程-v2=-2a·s
所以v02=2v2,v0=
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824143312936336.png)
再根据
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824143313389270.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824143313404551.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824143313389270.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824143313498930.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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