题目内容
如图在北戴河旅游景点之一的滑沙场有两个坡度不同的滑道AB和AB′(都可看作斜面)。甲、乙两名旅游者分别乘两个滑沙橇从插有红旗的A点由静止出发同时沿AB和AB′滑下,最后都停在水平沙面BC上.设滑沙橇和沙面间的动摩擦因数处处相同,滑沙者保持一定姿势坐在滑沙橇上不动。下列说法中正确的是
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250012549762616.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250012549762616.png)
A.甲的滑行总路程比乙短 |
B.甲、乙停止滑行后回头看A处的红旗时视线的仰角一定相同 |
C.甲在B点的速率等于乙在B′点的速率 |
D.甲全部滑行过程的水平位移一定比乙全部滑行过程的水平位移大 |
B
试题分析:据题意,设AB和AB’高度均为h,则甲从AB下滑过程中由动能定理有:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250012550381384.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001255101955.png)
经过整理得到甲从出发点开始的水平位移为:x甲=
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250012551321127.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001255147450.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250012550381384.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250012551791152.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250012551941168.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001255210447.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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