题目内容
(13分)如图所示,一物块(视为质点)质量为m=2Kg,以速度
0=3m/s的速度水平滑上一木板的左端,木板的上表面离水平地面的高度为h=0.8m,木板长为L=2m,质量为M=10Kg。木板与水平地面间的动摩擦因数μ1=0.1,取
,不计空气阻力。请解答如下问题:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250018580984717.jpg)
(1)若保持物块与木板表面间光滑,求物块落地点D到木板左端的水平距离![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001858113300.png)
(2)若物块与木板上表面间的动摩擦因数μ2="0.2," 求物块落地点E(图中未画出)到木板左端的水平距离
。
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001858066265.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001858082657.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250018580984717.jpg)
(1)若保持物块与木板表面间光滑,求物块落地点D到木板左端的水平距离
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001858113300.png)
(2)若物块与木板上表面间的动摩擦因数μ2="0.2," 求物块落地点E(图中未画出)到木板左端的水平距离
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001858129331.png)
(1)3.2m (2)2.4m
试题分析:(1) 物块与木板表面间光滑,物块在木板上做匀速直线运动,木板不动,物块从木板右端飞出做平抛运动,竖直方向有:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001858144650.png)
水平方向有:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001858160492.png)
联立解得t=0.4s x=1.2m
落地点D到木板左端的水平距离
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001858113300.png)
(2)物块与木板之间的摩擦力为:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250018581911091.png)
木板和地面之间的最大静摩擦力为
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250018582071093.png)
因为
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001858222457.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001858238974.png)
代入数据解得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001858269592.png)
平抛后在水平方向上有
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001858285411.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001858300535.png)
物块落地点E(图中未画出)到木板左端的水平距离为
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001858129331.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
练习册系列答案
相关题目