how can i solve part 2 ... should i convert the statespace to tf?

close all;
clear all;
clc;
m1=1;
m2=3;
k1=10;
k2=2;
b=0.5;
A=[0 1 0 0;-(k1+k2)/m1 -b/m1 k2/m1 b/m1;0 0 0 1; k2/m2 b/m2 -k2/m2 -b/m2];
B=[0;0;0;1/m2];
C=[1 0 0 0;0 0 1 0];
D=[0;0];
sys_ss=ss(A,B,C,D);
step(sys_ss);
[num,den]=ss2tf(A,B,C,D);

Answer 1

[Birdman]

Actually you do not need to do that since they will eventually give the same result but since the question wants you to do it, write the following code:

Gs(1)=tf(num(1,:),den);
Gs(2)=tf(num(2,:),den)
step(Gs)

and you will see that you get identical results.

[Mohammad Adeeb]

from where can i get the value of num and den ... from the convert ss into a tf?

[Birdman]

Yes exactly. From the following line

 [num,den]=ss2tf(A,B,C,D);

I get the values of num and den.

[Mohammad Adeeb]

ok .. thanx it's work

[Birdman]

You are welcome.