题目内容
(16分) 如图所示,质量m =" 2.0" kg的木块静止在高h =" 1.8" m的水平台上,木块距平台右边缘10 m,木块与平台间的动摩擦因数µ= 0.2。用水平拉力F = 20N拉动木块,当木块运动到水平末端时撤去F。不计空气阻力,g取10m/s2。求:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241222103822728.jpg)
(1)木块离开平台时的速度大小;
(2)木块落地时距平台边缘的水平距离。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241222103822728.jpg)
(1)木块离开平台时的速度大小;
(2)木块落地时距平台边缘的水平距离。
(1)
m/s
(2)x=
m
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122210398286.gif)
(2)x=
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122210398355.gif)
(1)对小物受力分析,由牛顿运动定律得:
??????
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122210413509.gif)
??????
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122210429392.gif)
??????解得:v=
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122210398286.gif)
(2)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122210460343.gif)
??????
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122210476473.gif)
??????解得:x=
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122210398355.gif)
![](http://thumb2018.1010pic.com/images/loading.gif)
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