不同惯性系中的力学规律

由力学相对性原理可知，在不同惯性系中，一切力学规律（如牛顿运动定律、动量定理、动量守恒定律、角动量定理等）的形式都相同．但在一个惯性系中机械能（或角动量）守恒，在另一惯性系中观察机械能（或角动量）却不一定守恒．

THE LAWS OF MECHANICS IN DIFFERENT INERTIAL SYSTEMS

By the principle of relativity in mechanics, we know that the basic laws in mechanics have the same form in different inertial systems, including, for example, the Newton's laws of motion, the theorem of momentum, the law of conservation of momentum, the theorem of angular momentum, etc. While in one inertial system the mechanical energy (or angular momentum) is conserved, in antoher inertial system it may not be so.