题目内容
让小球从斜面的顶端滚下,如图所示是用闪光照相机拍摄的小球在斜面上运动的一段,已知闪频为10 Hz,且O点是0.4 s时小球所处的位置,试根据此图估算:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/2014082500151617211306.png)
(1)小球从O点到B点的平均速度;(2)小球在A点和B点的瞬时速度;
(3)小球运动的加速度.
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/2014082500151617211306.png)
(1)小球从O点到B点的平均速度;(2)小球在A点和B点的瞬时速度;
(3)小球运动的加速度.
(1) 0.8 m/s (2) 1.0 m/s (3) 2.0 m/s2
试题分析:依题意知,相邻两次闪光的时间间隔Δt=
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001516187333.png)
(1)vOB=
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001516203507.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001516218672.png)
(2)小球在A点时的瞬时速度vA=
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001516203507.png)
小球在B点时的瞬时速度vB=
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001516234520.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001516265872.png)
(3)由加速度的定义得
小球的加速度a=
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001516281600.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001516296545.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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