%1C)
function zdot = zdot(t,z);
mh=90;
mr=10;
ma=10;

wa=100*pi;
ka = wa.^2*ma;
kh=8950000;
wh=sqrt(kh/(mh+mr));

e=0.2;
c=3000;
nc=0.1*2*ma*wh;

noll1=zeros(2,1);
noll2=zeros(2,2);

CI=[c+0, -0; -0, 0];
CII=[c+nc,-nc;-nc,nc];

M=[(mh+mr),0;0,ma];
K=[(kh+ka),-ka;-ka,ka];

AI=[CI,M; M,noll2];
AII=[CII,M; M,noll2];

B=[K,noll2; noll2, -M];
F=[-mr*e*wa.^2*sin(wa*t);0];
f=[F;noll1];

zdot=-inv(AI)*B*z+inv(AI)*f;