If the spring can change suddenly, it means that there is displacement in the limit time, X / T = V (time limit), and the pushing speed is infinite (but the speed cannot be infinite) But if one end of the spring is not connected with a mass object, the deformation of the light spring does not need time, can the elastic force change suddenly?
At this time, X is the difference value, which should be v = (x2-x1) / T. when the displacement is negative and the velocity is positive, there is x2 & lt; x1, then there is x2-x1 & gt; 0. When the velocity is positive, the direction of displacement is positive and negative is self-determined, and the spring oscillator is stable