题目内容
(13分)摩托车以
m/s的速率沿平直公路行驶,驾驶员突然发现正前方
处有一辆汽车.汽车的初速度大小为
m/s,此时汽车减速的加速度大小为
。为了避免发生碰撞,摩托车也同时减速(不计反应时间),求下列各种情况下摩托车减速的加速度大小
至少为多少?
(1)
m/s2(即汽车匀速行驶),
m;
(2)
m/s2,
m;
(3)
m/s2,
m。
![](http://thumb.zyjl.cn/pic2/upload/papers/20140825/20140825001616278467.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140825/20140825001616356258.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140825/20140825001616372445.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140825/20140825001616403344.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140825/20140825001616419315.png)
(1)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140825/20140825001616481422.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140825/20140825001616497410.png)
(2)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140825/20140825001616512397.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140825/20140825001616528425.png)
(3)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140825/20140825001616512397.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140825/20140825001616559408.png)
(1)
m/s2(2)
m/s2(3)
m/s2
![](http://thumb.zyjl.cn/pic2/upload/papers/20140825/20140825001616575371.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140825/20140825001616590540.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140825/20140825001616606504.png)
试题分析:(1)设摩托车经过时间
![](http://thumb.zyjl.cn/pic2/upload/papers/20140825/20140825001616622291.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140825/20140825001616637651.png)
此段时间内摩托车的位移
![](http://thumb.zyjl.cn/pic2/upload/papers/20140825/20140825001616668785.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140825/20140825001616684802.png)
如果速度相同时恰好不相撞,此时对应的加速度
![](http://thumb.zyjl.cn/pic2/upload/papers/20140825/20140825001616419315.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140825/20140825001616715494.png)
代入数值可得:
![](http://thumb.zyjl.cn/pic2/upload/papers/20140825/20140825001616575371.png)
(2)解法同(1),代入数值可得:
![](http://thumb.zyjl.cn/pic2/upload/papers/20140825/20140825001616590540.png)
(3)同上解法得
![](http://thumb.zyjl.cn/pic2/upload/papers/20140825/20140825001616762540.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140825/20140825001616778390.png)
故:汽车的位移
![](http://thumb.zyjl.cn/pic2/upload/papers/20140825/20140825001616809824.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140825/20140825001616824702.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140825/20140825001616840819.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140825/20140825001616606504.png)
![](http://thumb.zyjl.cn/images/loading.gif)
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