【简答题】如图所示,边长分别为0.2米和0.1米的实心正方体A、B放置在水平地面上, ρ A 为0.1×10 3 千克/米 3 ,ρ B 为0.8×10 3 千克/米 3 . 求: (1)物体A的质量m A (2)物体B对地面的压力F B (3)小明和小华两位同学设想在正方体A、B上部沿水平方向分别截去一定的厚度后,通过计算比较A、B剩余部分对地面压强的大小关系。小明设想在A、B的上部均截去0.09米,小华...
【单选题】There are strange dancing lights in the Arctic skies. Some call these the northern lights. If you want to see the northern lights, the first thing that you have to do is go out at night. You won't see...