均质等厚薄平板如图所示，则其重心的坐标为 ______ _____ 。http://image.zhihuishu.com/zhs/onlineexam/ueditor/201812/2fea49a78fd94e9d8f35226008ebec0d.png
举一反三
- 均质等厚薄平板如图所示，则其重心的坐标为___________。http://image.zhihuishu.com/zhs/onlineexam/ueditor/201812/2fea49a78fd94e9d8f35226008ebec0d.png
- 在横截面积等其他条件均相同的条件下，压杆采用（）所示的截面形状，其稳定性最好。 A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201812/cde5a8d5534f40b890e9156e7f05ea94.png" /> B: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201812/41e79439d2fd46fca429c2663fe0bbca.png" /> C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201812/af2d8363d9be44bd8dc3f3e96310748b.png" /> D: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201812/d427ec9070724523b4f4d924c2a2daf0.png" />
- 一质点在平面上作一般曲线运动，其瞬时速度为<img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201812/072ecbf2079c40debf10e59602baef5a.png" />，瞬时速率为<img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201812/a7c386a2ed9641fb872fd3798d8a18d6.png" />，某一段时间内的平均速度为<img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201812/fd7b24d84b0c48b29b905c0accbfb682.png" />，平均速率为<img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201812/25c97028c3294855859e6d26731aecd6.png" />，它们之间的关系必定有（ ） A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201812/28eb779628f849cb9c561087ac27668c.png" /> B: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201812/332a22fc817749108da3ea994f11c24e.png" /> C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201812/9fee0e92ea9344e18d11908ba83a7529.png" /> D: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201812/258f415ef0974549b35f450f710027de.png" />
- 拉普拉斯（Laplace）方程的表达式为（ ）。 A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201812/26731bcad75f41389448b29292940653.jpg" /> B: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201812/40e7e55a72ee44f59b45d20c84ebe3a6.jpg" /> C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201812/c65a79ea4d754174b99f34020d6e1735.jpg" /> D: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201812/139e8d3dc37941549e7b6b1731243172.jpg" />
- 平面一维稳定渗流的压力分布公式为（ ）。 A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201812/d08348f3b84f442d87994311dc13686b.jpg" /> B: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201812/2df214c86c5e4103897ba81ce2c6cd98.jpg" /> C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201812/cc98e4a778cc463c965ac8115e028f86.jpg" /> D: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201812/bc82177c19d44acfa1b365c3d66ed0a4.jpg" />