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在普通物理的教學中,講到力學中機械能守恆定律、動量守恆定律和角動量守恆定律的時候,我們對於這三條定律的適用範圍,往往不很强調或不很注意。我們摘引梁寶洪所譯的福里斯—季莫列娃普通物理學中的幾段有關的材料來看一下。在第一卷第66頁上有着關於動量不滅定律的敘述:“構成一封閉系統的各物體底動量底向量和,即這封閉系統底總動量向量,在整個的運動期間內保持不變”。而關於封閉系統的敘述則是“物體彼此之間相互作用,但不舆這系統外部的物體相互作用”。在93頁有着能底不滅和轉换定律的敘述:“對於一封閉的系統(外力之功等於零),當一切過程在這系統內部發生時,這系統底能量保持不變,在此情形下,能量可以從某種形式轉變為另一
In the teaching of general physics, when it comes to the law of conservation of mechanical energy, the law of conservation of momentum and the law of conservation of angular momentum in mechanics, we often do not emphasize or pay close attention to the scope of application of these three laws. Let’s take a look at a few paragraphs about the general physics of Forres-Timorelev translated by Liang Baohong. On page 66 of the first volume, there is a description of the law of invariance of momentum: “The sum of the base vectors of the base velocities of objects that form a closed system, ie, the total base moment vector of the closed system, remains constant throughout the period of motion.” The closed system is narrated as “objects interacting with each other but not interacting with objects outside the system.” On page 93 there is a description of the law of immortality and conversion: "For a closed system (the power of external work equals zero), the energy of the system remains constant as all processes occur within the system, in which case the energy You can change from one form to another