题目内容
如图甲所示,一半径R=1m、圆心角等于143°的竖直圆弧形光滑轨道,与斜面相切于B处,圆弧轨道的最高点为M,斜面倾角θ=370,t=0时刻有一物块沿斜面上滑,其在斜面上运动的速度变化规律如图乙所示。若物块恰能到达M点,(取g=10m/s2,sin370=0.6,cos370=0.8),求:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241214265004835.jpg)
(1)物块经过B点时的速度
;
(2)物块与斜面间的动摩擦因数
;
(3)AB间的距离
。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241214265004835.jpg)
(1)物块经过B点时的速度
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121426515351.png)
(2)物块与斜面间的动摩擦因数
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121426578301.png)
(3)AB间的距离
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121426609446.png)
(1)![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121426656741.png)
(2)![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121426702459.png)
(3)![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121426749688.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121426656741.png)
(2)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121426702459.png)
(3)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121426749688.png)
(1)由题意知:
在M点有
(1’)
由机械能守恒定律:
(1’)
代入数据可求得:
(1’)
(2)v-t图可知物块运动的加速度 a=10m/s2 (1’)
由牛顿第二定律:
(1’)
∴ 物块与斜面间的动摩擦因数
(1’)
(3)由运动学公式
(1’)
又![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121426952631.png)
∴
(1’)
在M点有
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121426780830.png)
由机械能守恒定律:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241214268271405.png)
代入数据可求得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121426656741.png)
(2)v-t图可知物块运动的加速度 a=10m/s2 (1’)
由牛顿第二定律:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241214268581046.png)
∴ 物块与斜面间的动摩擦因数
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241214268901149.png)
(3)由运动学公式
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121426921751.png)
又
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121426952631.png)
∴
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121426749688.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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