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在2014年新课标卷物理考纲中增加的内容:选修模块3-5,在主题“碰撞与动量守恒”下增加“动量定理”并作Ⅱ级要求.这就要求教师在备考过程中体现出考纲的变化.尤其是“微元思想”在动量定理解题中的应用,要想解好此类题从以下三个方面作起.一、建立一种模型——柱体模型对于流体问题,可沿流速v的方向选取一段柱形流体,设在Δt时间内通过某一横截面S的流体长度为Δl,如图1所示,若流体的密度为ρ,那么,在这
In the 2014 New Curriculum Physical Exercises, we added the following contents: Elective module 3-5, adding “Momentum Theorem” under the theme of “Conservation of Collision and Momentum” The process reflects the changes in the syllabus.Especially the application of “micro-yuan idea” in the solution of the momentum theorem, in order to understand such problems from the following three aspects: First, to establish a model - column Body model For the fluid problem, a section of columnar fluid can be selected along the flow velocity v, and the length of the fluid passing through a certain cross section S in Δt time is Δl. If the density of the fluid is ρ, At this