题目内容
如图所示,在倾角θ=37°的固定斜面的底端有一静止的滑块,滑块可视为质点,滑块的质量m=1kg,滑块与斜面间的动摩擦因数
,斜面足够长。某时刻起,在滑块上作用一平行于斜面向上的恒力F=10N,恒力作用时间t1=4s后撤去。(sin370=0.6)求:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250018465541959.png)
(1)撤去推力时物体的速度是多少?
(2)物体运动到最高点时的离地高度?
(3)物体滑回出发点时的速度大小?(g=10m/s2)。
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001846538536.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250018465541959.png)
(1)撤去推力时物体的速度是多少?
(2)物体运动到最高点时的离地高度?
(3)物体滑回出发点时的速度大小?(g=10m/s2)。
(1)16m (2)20m (3)![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001846569644.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001846569644.png)
试题分析:(1)据题意,4s前物体在恒力作用下做匀加速直线运动,
有
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250018465851053.png)
得a1=2m/s2 1分
由公式
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001846647506.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001846663695.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001846678889.png)
(2)撤去恒力物体向上做匀减速直线运动,
有
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250018466941017.png)
得a2=8m/s2 1分
由公式
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001846710647.png)
x2=4m 1分
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001846725717.png)
(3)物体下滑后
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001846741997.png)
得a3=4m/s2 1分
由公式
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001846756609.png)
得
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001846788719.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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