كلما زادت كتلة صندوق، فإنه يحتاج لقوة أكبر لدفعه. قانون نيوتن الثاني

] Consequently, the mass of the system can not change during the time of interest Quoting Newton in the Principia: It is not one action by which the Sun attracts Jupiter, and another by which Jupiter attracts the Sun; but it is one action by which the Sun and Jupiter mutually endeavour to come nearer together
Celestial Mechanics and Dynamical Astronomy

قانون نيوتن الثاني: ديناميكا الجسيمات

"On the use and abuse of Newton's second law for variable mass problems".

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I]t is essential to deal with the same set of particles throughout the time interval[
قانون نيوتن الثاني
Cambridge UK: Cambridge University Press
قانون نيوتن الثاني
Metaphysics Research Lab, Stanford University
Cambridge UK: Cambridge University Press Hannah, J, Hillier, M J, Applied Mechanics, p221, Pitman Paperbacks, 1971• When the mass varies due to accretion or ablation, [an alternate equation explicitly accounting for the changing mass] should be used
I Bernard Cohen Peter M Any single force is only one aspect of a mutual interaction between two bodies

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.

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قانون نيوتن الثاني: ديناميكا الجسيمات
كلما زادت كتلة صندوق، فإنه يحتاج لقوة أكبر لدفعه,