刚体的A、B、C三点作用有三个力，恰好构成封闭的三角形，刚体平衡。https://image.zhihuishu.com/zhs/onlineexam/ueditor/201910/be9f2fa90d334738b8f8d6ae01203a1b.png
举一反三
- 刚体的A、B、C三点作用有三个力,恰好构成封闭的三角形,刚体平衡。
- 在刚体上的A点加一力F，如图所示，能否在B点加一个力使得刚体处于平衡状态？能https://image.zhihuishu.com/zhs/onlineexam/ueditor/201910/642a54c7254e4d94bd863acc9df21c46.png
- 刚体在A、B、C三点受F1、F2和F3三力作用。若此三力等值，且作用线互成60°夹角，构成的力三角形恰好封闭。故刚体处于平衡状态。
- 图中三个力的大小都不等于零，其中两个力的作用线共线。刚体在此三个力作用下：不能平衡https://image.zhihuishu.com/zhs/onlineexam/ueditor/201910/0049b222ab344a53965bcd7d07f6e438.png
- 设EI为常数，图示刚架支座C点的水平位移为（ ）。<img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201910/2dea6754bc2a40df98d40ddc4d88e4ee.png"/> A: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201910/876c3a939abd447fae12277cbbdf2885.png"/> B: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201910/9452dbf33f1b42bab8d279978b5294d8.png"/> C: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201910/c86de891367447249efb95cf363ee7cf.png"/> D: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201910/ba048b2d5eb149fbbe5a7b419903ef5b.png"/>