题目内容
(7分)如图所示,质量m=2.0kg的金属块(可视为质点)静止在高h=1.8m的光滑水平台面上。现用水平恒力F=9.0N拉动金属块,当金属块向右运动s=4.0m时撤去拉力F,之后金属块在台面上滑行一段距离后飞离台面。空气阻力忽略不计,g取10m/s
。求:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408242208583802311.jpg)
(1)金属块离开台面时的速度大小v;
(2)金属块落地点距台面边缘的水平距离L;
(3)金属块落地时速度方向与竖直方向的夹角θ。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824220856805242.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408242208583802311.jpg)
(1)金属块离开台面时的速度大小v;
(2)金属块落地点距台面边缘的水平距离L;
(3)金属块落地时速度方向与竖直方向的夹角θ。
(1)6m/s(2)3.6m (3)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824220858973510.png)
试题分析:金属块在台面上滑行过程中,只有拉力F=9N做功,根据动能定理
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824220859800781.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824220900283636.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824220900673650.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824220901531489.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824220902389712.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824220900283636.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824220904854766.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408242209060402045.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824220906913750.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824220858973510.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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