演示环境（数据为演示用途，非真实数据）

狭义相对论教学中,运动质量的推导是核心重难点之一。现行大学物理教材多基于“两粒子聚合”或“单粒子分裂”过程推导运动质量公式,这类方法普遍依赖“质量守恒”的前提假设。然而,学生在该阶段仅掌握洛伦兹变换与相对论速度变换知识,尚未接触质能关系,对“质量随速度变化却仍守恒”的矛盾存在强烈困惑。若提前引入质能关系支撑假设,又会破坏教学逻辑的严谨性与连贯性,降低推导的说服力。针对这一问题,本文首先通过坐标系变换的严谨推导,证实粒子分裂前后的质量守恒关系;进而提出一种无需依赖特定物理过程、不预设质量守恒与质能关系的简易推导方法。该方法仅运用质心速度定义与相对论速度变换公式,即可完成相对论质量公式的推导,推导简单、逻辑清晰、易于理解,更契合狭义相对论的教学逻辑顺序,有助于学生建立正确的相对论时空观。

In the teaching of special relativity, the derivation of motion mass is one of the core and difficult points. Current university physics textbooks often derive the formula for the mass of motion based on the processes of “two particle aggregation” or “single particle splitting”, which generally rely on the assumption of “conservation of mass”. However, at this stage, students only have knowledge of Lorentz transformation and relativistic velocity transformation, and have not yet been exposed to the relationship between mass and energy. They have a strong confusion about the contradiction of “mass changing with velocity but still conserved”. If the assumption of supporting the relationship between quality and energy is introduced in advance, it will undermine the rigor and coherence of the teaching logic, and reduce the persuasiveness of the deduction. In response to this issue, this article first rigorously derives the mass conservation relationship before and after particle splitting through coordinate system transformation; Furthermore, a simple derivation method is proposed that does not rely on specific physical processes and does not presuppose the conservation of mass and the relationship between mass and energy. This method only uses the definition of centroid velocity and the formula for relativistic velocity transformation to derive the relativistic mass formula. The derivation is simple, logically clear, and easy to understand, which is more in line with the teaching logic sequence of special relativity and helps students establish a correct relativistic spacetime view.