题目内容
质量m=0.78 kg的木块静止于水平面上,现在恒力F作用下做匀加速直线运动,已知恒力大小F=4.5N,方向与水平方向成q=37°角斜向上,如图所示.3 s末撤去此拉力时,木块已滑行的距离s0=9m,(重力加速度g取10 m/s2,sin37°=0.6,cos37°=0.8.)求:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130513715993.png)
小题1: 木块与地面间的动摩擦因数;
小题2:撤去拉力后,木块继续滑行的距离;
小题3:在整个运动过程中,摩擦力对木块做的功.
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130513715993.png)
小题1: 木块与地面间的动摩擦因数;
小题2:撤去拉力后,木块继续滑行的距离;
小题3:在整个运动过程中,摩擦力对木块做的功.
小题1:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130513747449.png)
小题2:s=4.5 m
小题3:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130513778721.png)
(1)
(1分)
(1分)
(2分)
解得
(2分)
(2)3s末木块的速度:
(1分)匀减速阶段
(1分)
木块继续滑行的距离
(1分)解得:s=4.5 m (2分)
(3)对全过程分析
(2分)
又
(1分)
摩擦力对木块做的功
(2分
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130513793682.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130513825835.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130513856891.png)
解得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130513747449.png)
(2)3s末木块的速度:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130513887484.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130513903512.png)
木块继续滑行的距离
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130513934645.png)
(3)对全过程分析
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130513965662.png)
又
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130513996810.png)
摩擦力对木块做的功
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130513778721.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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