题目内容
质量M=1kg的物体,在水平拉力F的作用下,沿粗糙水平面运动,经过位移4m时,拉力F停止作用,运动到位移是8m时物体停止,运动过程中EK-S的图线如图所示。求:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408242313255334340.png)
(1)物体的初速度多大?
(2)物体和平面间的摩擦系数为多大?
(3)拉力F的大小?(g取10m/s2)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408242313255334340.png)
(1)物体的初速度多大?
(2)物体和平面间的摩擦系数为多大?
(3)拉力F的大小?(g取10m/s2)
(1)v0=2m/s (2) 0.25 (3)F="4.5N"
试题分析:(1)由图可知
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824231326235856.png)
(2) 撤去F后由动能定理得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824231327624827.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824231328544496.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824231329964301.png)
(3)开始从力F作用到停止的过程中,由动能定理得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408242313313051032.png)
代入数值可得:F=4.5N
![](http://thumb2018.1010pic.com/images/loading.gif)
练习册系列答案
相关题目