中文摘要：

相对论效应是相对论中存在而牛顿力学中不存在的，但为什么会产生这种差异？两种理论的什么不同导致了这种区别，它和牛顿力学的适用条件有何关系？已知牛顿力学有适用条件，那么相对论有适用条件吗？如何研究相对论的适用条件？相对论的适用条件是什么？本文详细讨论了上述问题，通过分析和建模给出了产生相对论效应的物理原因，提出了研究相对论适用条件的3种方法，并应用这些方法得到了2个相对论的适用条件，解释了一些历史遗留的问题。

英文摘要：

Relativistic effects exist in the theory of relativity,but not in Newtonian mechanics. What’s leading to this distinction of the two theories？What’s the relationship between this distinction and the applicable conditions of Newtonian mechanics？Does Relativity have applicable conditions？How to research the applicable conditions of relativity？What’s the applicable condition of relativity？This paper discusses these issues through analysis and modeling,gets the physical causes of forming relativistic effects,and proposes three researching methods of relativistic applicable conditions. Two applicable conditions of relativity have been obtained by these methods and explain some difficult problems handed down in physics.