两个有关机械能守恒问题的讨论

Discussion on conservation of mechanical energy

在基础力学教材中，有关功、能的定义，一般是以地球为参照系。这样易使学生产生错觉，认为功、能以及机械能守恒均与参照系无关，而且机械能守恒的系统一定是保守系。本文以具体实例讨论了两个相关的问题。

Usually the definition of work and energy takes the globe as frame of reference in some textbook of dynamic. This will gave students a false impression. Someone consider that work and energy and conservation of mechanical energy have nothing to do with frame of reference. This arctic discussed problem concerned.