题目内容
在场强为E =" 100" V/m的竖直向下匀强电场中有一块水平放置的足够大的接地金属板,在金属板的正上方,高为h = 0.8m处有一个小的放射源放在一端开口的铅盒内,如图所示。放射物以
=200m/s的初速度向水平面以下各个方向均匀地释放质量为m = 2
kg、电量为q = +
C的带电粒子。粒子最后落在金属板上,不计粒子重力,试求:
(1)粒子下落过程中电场力做的功;
(2)粒子打在板上时的动能;
(3)画出粒子大致的轨迹和最后落在金属板上所形成的图形;
(4)计算此图形面积的大小。(结果保留两位有效数字)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241140221002663.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114021944204.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114021960274.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114021976254.gif)
(1)粒子下落过程中电场力做的功;
(2)粒子打在板上时的动能;
(3)画出粒子大致的轨迹和最后落在金属板上所形成的图形;
(4)计算此图形面积的大小。(结果保留两位有效数字)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241140221002663.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114022210617.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241140222411111.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114022272521.gif)
(1)![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114022210617.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241140223192566.jpg)
(2)由动能定理
得:![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241140222411111.gif)
(3)如图
(4)粒子做类平抛运动,在竖直方向上做初速度为零的匀加速运动,![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114022506655.gif)
数据代入求得![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114022522517.gif)
在水平方向做匀速直线运动,圆半径即是粒子在水平方向的位移,![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114022537495.gif)
圆面积
。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114022210617.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241140223192566.jpg)
(2)由动能定理
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114022334483.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241140222411111.gif)
(3)如图
(4)粒子做类平抛运动,在竖直方向上做初速度为零的匀加速运动,
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114022506655.gif)
数据代入求得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114022522517.gif)
在水平方向做匀速直线运动,圆半径即是粒子在水平方向的位移,
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114022537495.gif)
圆面积
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114022272521.gif)
![](http://thumb2018.1010pic.com/images/loading.gif)
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