题目内容
23、按要求完成下列作图.
(1)在图中画出合适的透镜.
![](http://thumb.1010pic.com/pic3/upload/images/201012/64/1583c964.png)
(2)请画出图中足球受到的重力的示意图.
![](http://thumb.1010pic.com/pic3/upload/images/201012/64/1e86228b.png)
(3)画出图中动力F1相对支点O的力臂.
![](http://thumb.1010pic.com/pic3/upload/images/201012/64/f1aa5da8.png)
(1)在图中画出合适的透镜.
![](http://thumb.1010pic.com/pic3/upload/images/201012/64/1583c964.png)
(2)请画出图中足球受到的重力的示意图.
![](http://thumb.1010pic.com/pic3/upload/images/201012/64/1e86228b.png)
(3)画出图中动力F1相对支点O的力臂.
![](http://thumb.1010pic.com/pic3/upload/images/201012/64/f1aa5da8.png)
分析:(1)凹透镜对光线有发散作用,故是凹透镜.
(2)重力G的作用点在重心,方向是竖直向下.
(3)力臂是支点到力的作用线的距离.
(2)重力G的作用点在重心,方向是竖直向下.
(3)力臂是支点到力的作用线的距离.
解答:解:(1)![](http://thumb.1010pic.com/pic3/upload/images/201103/7/592a2265.png)
(2)![](http://thumb.1010pic.com/pic3/upload/images/201103/7/20b8007f.png)
(3)![](http://thumb.1010pic.com/pic3/upload/images/201103/7/6eb1654f.png)
![](http://thumb.1010pic.com/pic3/upload/images/201103/7/592a2265.png)
(2)
![](http://thumb.1010pic.com/pic3/upload/images/201103/7/20b8007f.png)
(3)
![](http://thumb.1010pic.com/pic3/upload/images/201103/7/6eb1654f.png)
点评:本题考查了凹透镜的发散作用、重力的示意图和力臂的画法.力臂是要画出支点到力的作用线的垂线段.
![](http://thumb2018.1010pic.com/images/loading.gif)
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