解 2 E=Epx+omv v m e-EplX 2[E-Ep(x=dx v= m dx 2(E-E(4 X t- ldt- 0 2 N m E-Eplx 目录结束E (x) P mv 2 1 2 =E + 2 m v 2 = E (x) EP dt = 2 m v = E (x) EP dx dt = 2 m E (x) EP dx  dt = 2 m E (x) EP dx t 0 t =  x 0 解： 目录 结束