题目内容
(6分)汽车从制动到停止下来共用了5s。这段时间内,汽车每1s前进的距离分别是18m、14m、10m、6m、2m。求:
⑴汽车前1s、前2s、前3s、前4s和全程的平均速度;
⑵汽车运动的最后2s的平均速度。
⑴汽车前1s、前2s、前3s、前4s和全程的平均速度;
⑵汽车运动的最后2s的平均速度。
⑴18m/s,16m/s,14m/s,12m/s,10m/s;⑵4m/s。
试题分析:⑴根据平均速度的定义式可知,汽车在前1s的平均速度为:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000527458274.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000527473367.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000527489347.png)
在前2s的平均速度为:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000527505303.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000527520482.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000527536500.png)
在前3s的平均速度为:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000527551307.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000527629534.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000527676564.png)
在前4s的平均速度为:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000527692298.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000527707585.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000527723620.png)
在全程中的平均速度为:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000527739259.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000527754644.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000527770722.png)
⑵汽车在最后2s的平均速度为:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000527785284.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000527801464.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000527817447.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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