题目内容
(10分)如图所示,质量M=
kg的木块A套在水平杆上,并用轻绳将木块:A与质量m=
kg的小球相连。今用跟水平方向成α=300角的力F=
N,拉着球带动木块一起向右匀速运动,运动中M、m相对位置保持不变,取g=10m/s2。求:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250053134642637.png)
(1)运动过程中轻绳与水平方向夹角θ;
(2)木块与水平杆间的动摩擦因数为μ。
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005313386397.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005313401308.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005313432419.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250053134642637.png)
(1)运动过程中轻绳与水平方向夹角θ;
(2)木块与水平杆间的动摩擦因数为μ。
(1)
;(2)![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005313495559.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005313479494.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005313495559.png)
试题分析:(1)设细绳对B的拉力为T,由平衡条件可得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005313526751.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005313542957.png)
解得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005313557662.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005313588678.png)
即
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005313479494.png)
(2)设细绳对A的拉力为
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005313620332.png)
则:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005313635383.png)
有:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005313666914.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005313682762.png)
可得
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005313495559.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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