Σ (Subscript[f, (Subscript[E, 1])])=m(Overscript[x, ¨])=F-C(OverDot[x])-KxF=m(Overscript[x, ¨])=C(OverDot[x])=Kx(F/m)=(Overscript[x, ¨])=(C/m)(OverDot[x])=(K/m)x