题目内容
(15分)一滑块从离光滑斜面底端为30m处以初速度v0=10m/s沿着斜面上滑,已知滑块在光滑斜面上运动的加速度大小为a=5m/s2, 方向始终沿斜面向下,滑块没有从顶端离开斜面,求滑块滑到斜面底端的时间。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241155261381155.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241155261381155.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115526138488.png)
方法1,滑块滑到斜面最上端需
滑块到斜面最上端与初始位
置相距
,由
得滑块从最上端滑到底端需
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241155262941316.png)
所以![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115526325621.png)
方法2 由
,选初速方向为正,则有
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115526138488.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115526169679.png)
置相距
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115526231721.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115526247601.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241155262941316.png)
所以
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115526325621.png)
方法2 由
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115526340712.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115526387732.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115526450620.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115526138488.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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