均质杆 OA 长 L ，质量为 m ，则撞击中心 K 到轴 O 的距离为 ___ ______ 。http://image.zhihuishu.com/zhs/onlineexam/ueditor/201812/31f2048ca729431e87e849cd8d7d12a7.png
举一反三
- 质量为 m ，长为 L 的匀质杆 OA ，以匀角速度 w 绕 O 轴转动。图示位置时，杆的动量及对 O 轴的动量矩的大小为 _ ______ 。http://image.zhihuishu.com/zhs/onlineexam/ueditor/201812/6bd41030f0bf4ac3a9fcfb77284d015c.png
- 均质细杆OA长L，质量为m，自铅直位置经微小扰动后绕O轴倒下，至水平位置时与一尖角B相碰，为使轴O处不产生碰撞冲量，OB的距离h应为_____。http://image.zhihuishu.com/zhs/onlineexam/ueditor/201812/2f24848d7f3a47be8fd45b64356266f1.png
- 图中各杆均为均质杆。已知杆 OA ， CD 质量均为 m ，杆 AB 质量为 2 m ，且 OA = AC = CB = CD = L ，杆 OA 以角速度 w 转动，则图示瞬时， OA 杆对 O 点动量矩的大小为 _______________________ ； AB 杆对 C 点动量矩的大小为 ____________________ ； CD 杆对 D 点动量矩的大小为 _________________________ ，转向均应在图中标出。http://image.zhihuishu.com/zhs/onlineexam/ueditor/201901/abfa22ff9fe64c3eaae2cae0501521ef.png
- 略去质量的弹簧原长为2L，刚度为k，两端固定并处于水平位置，在弹簧中点挂一重物，则重物下降x路程中弹性力所作的功为________。<img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201812/a23821c4ff754f00aa2f3bdcbff7740f.png" /> A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201812/484da0f3795d4eb39a41a86f9515c4d6.png" /> B: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201812/a11e055bb31c450c8a9359b0339db3bf.png" /> C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201812/6b19f1dc9b8b40ce92f397749e440b2c.png" /> D: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201812/a1a5d63b6d424b68a3e81a565a849360.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" />