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物理习题中有一类热学、力学的综合性题型,近几年在中考题中也频频出现,学生做起来头痛,正确率低,教师讲起来也很费劲,但如果我们利用数学公式稍加变换,问题就简单了.题目在下面的三个容器中装适量的液体,分别从容器底部微微加热,液体对容器底的压强怎样变化?(忽略容器的热膨胀以及液体蒸发).分析若用液体压强公式 p_液=ρ_液gh 来讨论,当对容器底加热时,液体密度ρ_液变小,深度 h 变大,液体对容器底的压强 p_液不能确定.为此我们换个角度,考虑到容器内液体为圆台体或圆柱体(特殊圆台体),加热前后容器底
There are one type of thermal and mechanical comprehensive questions in physics exercises. In recent years, they have also appeared frequently in the examination questions. Students have headaches and the correct rate is low. Teachers also struggle with speaking, but if we use mathematical formulas to slightly change The problem is simple. Question: The following three containers are filled with the appropriate amount of liquid, which is heated slightly from the bottom of the container. How does the pressure of the liquid on the bottom of the container change? (Ignore the thermal expansion of the container and evaporation of the liquid). Analyze if liquid pressure is used. The formula p_liquid = ρ_liquid gh is discussed. When the bottom of the vessel is heated, the liquid density ρ_liquid becomes smaller, the depth h becomes larger, and the pressure of the liquid on the bottom of the vessel p_liquid cannot be determined. Therefore, we change the angle, Considering that the liquid in the container is a circular table or a cylinder (special circular table), the bottom of the container before and after heating is heated