题目内容
一个质点以初速度v0=2m/s开始做匀变速直线运动,经过t =4s,前进位移x=16m,试求:
(1)质点的加速度大小
(2)第6s末质点的速度大小
(3)质点前6s内的平均速度大小
(1)质点的加速度大小
(2)第6s末质点的速度大小
(3)质点前6s内的平均速度大小
(1)1m/s2 (2)8m/s (3)5m/s
试题分析:(1)方法①:由匀变速直线运动规律
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001550679776.png)
方法②:前4s的平均速度为
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001550694840.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001550710610.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001550726602.png)
(2)由
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001550741560.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001550757622.png)
(3)方法①:前6s内的平均速度就是这段时间中间时刻的速度即3s末时速度,代入
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001550741560.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001550804610.png)
方法②:由前6s的位移与6s的比值,即可得平均速度。
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250015508191031.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001550835845.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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