题目内容
质量
=3 kg的物体,仅在水平拉力F=6 N的拉力作用下,在光滑的水平面上从静止开始运动,运动时间t=3 s ,求:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824135354118455.png)
(1)物体在3 s内物体的位移;
(2)F在3 s内对物体所做的功的平均功率;
(3) 3 s末力F对物体所做的功的瞬时功率。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824135354087337.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824135354118455.png)
(1)物体在3 s内物体的位移;
(2)F在3 s内对物体所做的功的平均功率;
(3) 3 s末力F对物体所做的功的瞬时功率。
(1)9M(2) 18W(3)36W
:(1)
,![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241353548051064.png)
(2)W=Fx=6×9J=54J![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241353548521095.png)
(3)v=at=2×3m/s=6m/s,P=Fv=6×6W=36W
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241353545081085.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241353548051064.png)
(2)W=Fx=6×9J=54J
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241353548521095.png)
(3)v=at=2×3m/s=6m/s,P=Fv=6×6W=36W
![](http://thumb2018.1010pic.com/images/loading.gif)
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