The shown spring problem can be solved using DEQME : F2 G enter
w=9.81 (to make coeff=1)
g=9.81
b=0
k=64
F=0
Hit ENTER about 7 times , Variation of Parameter will be used to solve, then you may enter your initial conditions
x0=0
y(x0)=2/3
y'(x0)=-4/3
Voila!!
