题目内容
(15分)如图所示,质量M
的木块套在水平杆上,并用轻绳与质量
的小球相连。今用跟水平方向成
角的力
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
求:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241223268223138.jpg)
(1)运动过程中轻绳与水平方向夹角
;
(2)木块与水平杆间的动摩擦因素
。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122326261429.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122326370448.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122326385292.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122326401477.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122326417197.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122326463463.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241223268223138.jpg)
(1)运动过程中轻绳与水平方向夹角
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122326838200.gif)
(2)木块与水平杆间的动摩擦因素
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122326963204.gif)
(1)![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122327009229.gif)
(2)![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122327025322.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122327009229.gif)
(2)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122327025322.gif)
(1)以球为研究对象,球受力如图所示
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241223270562462.jpg)
据共点力平衡条件得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241223270721521.gif)
其中
…………③
解①②③得![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122327103953.gif)
(2)以木块A为研究对象,其受力如图所示
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241223271192986.jpg)
据共点力平衡条件得
----------(2分)
------------------------(2分)
其中
, -----------------------------------(1分)
解得
-----------------------------------(2分)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241223270562462.jpg)
据共点力平衡条件得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241223270721521.gif)
其中
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122327087537.gif)
解①②③得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122327103953.gif)
(2)以木块A为研究对象,其受力如图所示
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241223271192986.jpg)
据共点力平衡条件得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122327134526.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122327165644.gif)
其中
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122327181416.gif)
解得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122327025322.gif)
![](http://thumb2018.1010pic.com/images/loading.gif)
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