由拉格朗日函数讨论力学中的守恒定律

Deduction of conservation law in mechanics from Lagrange function

由保守系的拉格朗日方程可以得到守恒定律.时间和空间的对称性决定了系统的拉格朗日函数的改变量为零,由此可以推出相应的守恒定律.

Based on the Lagrange equation,conservation law of mechanics can be gained.Lagrange function of mechanics system did not change because of the symmetry of time and space,so we can present corresponding conservation law.