题目内容
(13分)如图所示,绷紧的传送带,始终以2 m/s的速度匀速斜向上运行,传送带与水平方向间的夹角θ=30°。现把质量为10 kg的工件轻轻地放在传送带底端P处,由传送带传送至顶端Q处。已知P、Q之间的距离为4 m,工件与传送带间的动摩擦因数为μ=
,取g=10 m/s2。
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250007551902618.jpg)
(1)通过计算说明工件在传送带上做什么运动;
(2)求工件从P点运动到Q点所用的时间。
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000755174453.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250007551902618.jpg)
(1)通过计算说明工件在传送带上做什么运动;
(2)求工件从P点运动到Q点所用的时间。
(1)工件先以
的加速度匀加速运动
此后匀速(2)![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000755237491.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000755206592.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000755221481.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000755237491.png)
试题分析:初始阶段传送带速度
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000755252571.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250007552681130.png)
当其速度匀加速到
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000755252571.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000755299979.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000755315743.png)
二者速度相等时还没有到达最高点,继续运动,最大静摩擦力
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250007553461010.png)
所以工件先以
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000755206592.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000755221481.png)
(2)匀速运动的位移
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000755393736.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000755408716.png)
工件从P点运动到Q点所用的时间
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000755424652.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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