3.一沿x轴作简谐振动的弹簧振子,振幅为A,周期为T,当 https:/img.zuoyebang.cc/zyb_bb901293bf872d43407f66d0487cc9ec.jpg=0 时振子过 =-A12 处,-|||-且向x轴负方向运动,则振子的初相为 ()-|||-A dfrac (4)(3)pi B dfrac (2)(3)pi C dfrac (1)(3)pi D 5/3π ;