题目内容
(14分)如图所示,光滑斜面倾角为30o,AB物体与水平面间摩擦系数均为μ=0.4,现将A、B两物体(可视为质点)同时由静止释放,两物体初始位置距斜面底端O的距离为LA=2.5m,LB=10m。不考虑两物体在转折O处的能量损失,。
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250035532233325.jpg)
(1)求两物体滑到O点的时间差。
(2)B从开始释放,需经过多长时间追上A?
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250035532233325.jpg)
(1)求两物体滑到O点的时间差。
(2)B从开始释放,需经过多长时间追上A?
(1)
(2)2.34s
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003553238475.png)
试题分析:(1)A到达底端时间
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003553254813.png)
B到达底端时间
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003553269820.png)
A B到达底端时间差
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003553301476.png)
(2)A到达底端速度
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003553316845.png)
经过分析B追上A前,A已停止运动 1分
A在水平面上运动的总位移
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250035533471040.png)
B在水平面上运动的总位移
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250035533631111.png)
其中
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003553379927.png)
由 SA=SB 1分
t=
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003553394618.png)
则B从释放到追上A用时
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250035534101121.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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