题目内容
如图甲所示,质量m=5kg的物体静止在水平地面上的O点,如果用F1=20N的水平恒定拉力拉它时,运动的位移-时间图象如图乙所示;如果水平恒定拉力变为F2,运动的速度-时间图象如图丙所示.求:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241604356918069.jpg)
(1)物体与水平地面间的动摩擦因数;
(2)拉力F2的大小。(g=10m/s2)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241604356918069.jpg)
(1)物体与水平地面间的动摩擦因数;
(2)拉力F2的大小。(g=10m/s2)
0.4 30N
试题分析:用
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824160435753607.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824160436034822.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824160436237449.png)
如果水平恒定拉力变为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824160436439353.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241604365641097.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824160436767630.png)
点评:本题的关键是从图像中得出物体的运动性质,然后根据运动学规律分析
![](http://thumb2018.1010pic.com/images/loading.gif)
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