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1994年4月3日举行的全国《迎奥赛物理知识竞赛》试题中,出现了好几个物体浸在多层液体中时浮力问题的题目。师生就这些题目展开了热烈的讨论。重要争执点在于:液体各层密度不相同,阿基米德定律是否还适用?上层液体对物体有向下的压力,最下层则有向上的压力,中间各层有没有浮力?物体怎样才能恰好悬浮在多层液体中? 设水槽中有几种密度不同的液体,分层静止,不发生化学反应,又不相混合,物体为规则的正立柱形,底面积为S,如图1所示,竖立静止在液体中。液体的密度分别为ρ_1、ρ_2,……ρ_n。液层厚度分别为h_1,h_2,……
In the National Physics Meet Competition for the Olympics held on April 3, 1994, the subject of buoyancy was discovered when several objects were immersed in a multilayered liquid. Teachers and students had a lively discussion on these topics. The important disputes are: if the density of liquid layers is not the same, is Archimedes’s law also applicable? The upper liquid has downward pressure on the object, the lower layer has upward pressure, and the middle layer has no buoyancy. How can the object exactly match? Suspended in a multi-layered liquid? There are several liquids with different densities in the water bath, which are layered and stationary, do not react chemically, and do not mix. The objects are regular upright columns, and the bottom area is S, as shown in Figure 1. , stand still in the liquid. The density of the liquid is ρ_1, ρ_2, ... ρ_n, respectively. The thickness of the liquid layer is h_1, h_2,...