令w^2=k/m则振动方程：x=Acos(wt+fi)瞬时速度：v=-wAsin(wt+fi)根据周期定义：x=x`,v=v`(运动状态相同的两点)设周期为T代入上面两式：Acos(wt+fi)=Acos(w(t+T)+fi)-wAsin(wt+fi)=-wAsin(w(t+T)+fi)则 wt+fi+2kpi=w(t...