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学习完机械能一章后,学生提出这样的问题:动能大小由 m 和υ值来决定,而υ的大小与参考系选取有关,那么动能的大小是否也和参考系的选取有关呢?在地面参考系中成立的动能定理在其他惯性参考系中是否依然成立?对第一个问题,我给予了肯定的答复:物体动能的大小与参考系的选取有关,在不同参考系中同一时刻测同一物体的速度值是不同的,因而动能值也必然不同.在得到第一个问题的答复之后,学生迫不及待地给出了第二个问题的答案:动能定理在相对地面运动的其他惯性系中不成立,而且还给出了如下证明(显然
After learning the chapter on mechanical energy, the students asked the question: the magnitude of kinetic energy is determined by the values of m and ,, and the size of υ is related to the selection of the reference system. Then is the magnitude of kinetic energy also related to the selection of the reference system? Reference on the ground Is the kinetic energy theorem established in the system still valid in other inertial reference systems? For the first question, I gave a positive answer: The magnitude of the object’s kinetic energy is related to the selection of the reference system. The same object is measured at the same time in different reference frames. The speed values are different, and therefore the kinetic energy values are necessarily different. After getting the answer to the first question, the students can’t wait to give the answer to the second question: The kinetic energy theorem is not valid in other inertial systems that are relative to ground motion. And also gave the following proof (obvious