题目内容
一只圆盘绕竖直轴匀速转动,角速度为2 rad/s,质量为2kg的木块随着圆盘一起运动,木块到转轴O的距离为0.3m (
)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824134717176466.png)
(1)求此时物体所受摩擦力的大小并说明方向
(2)若将木块到O的距离增大至0.5m,此时木块恰好相对于圆盘不滑动,求木块与圆盘之间的动摩擦因数(设最大静摩擦等于滑动摩擦)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824134716801664.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824134717176466.png)
(1)求此时物体所受摩擦力的大小并说明方向
(2)若将木块到O的距离增大至0.5m,此时木块恰好相对于圆盘不滑动,求木块与圆盘之间的动摩擦因数(设最大静摩擦等于滑动摩擦)
(1)2.4N(2)0.2
(1)物体做匀速圆周运动
代入可得 ![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824134717269697.png)
静摩擦力提供向心力
————————(4分)
(2)当运动半径为0.5m时,向心力等于最大静摩擦力,等于滑动摩擦力
可得
————————(4分)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824134717223541.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824134717269697.png)
静摩擦力提供向心力
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824134717316444.png)
(2)当运动半径为0.5m时,向心力等于最大静摩擦力,等于滑动摩擦力
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824134717363692.png)
可得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824134717410942.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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