Coding questions with regards to Mechanical Vibrations (desperate for help)

a)Use the same model as in first case but for c=0.2 and let the driving frequency be constant ωdr=4 with zero initial conditions. Plot the motion of the system and describe the motion.

b) Let the force be accelerating such that (F sin(5t^2 /1000)). Plot the response (for c=0.2) for each mass as function of angular frequency. Explain the result

I have already solved part a) and i am currently stuck at part B

It requires me to plot the response for each mass as a function of angular frequency, does any one have any idea on how do I go about it?

I need to plot a Response curve however I only have managed to plot a single frequency curve right now.

How do i simulate the system for TIME DEPENDENT frequency?

i assume that the driving frequency (wdr= 5t^2/1000) is that correct?

My code is shown below:

 
% Simulation of forced 2DOF system with ode45
clear all
clc
global A B F Z I wdr
c=0.2;
m=1;
k=100;
c=0.2;
F0=10;
t0=0;
t1=100;
M=[m 0 0 ;0 m 0 ; 0 0 m];
K=[2*k -k 0;-k 2*k -k;0 -k k];
C=[2*c -c 0;-c 2*c -c;0 -c c];
f=[0 0 F0]';
    for t=t0:t1
      w=5*t/1000;
    end

wdr=w; % Driving frequency
A=M\K;
B=M\C;
F=M\f;
Z=zeros(3); % Zero matrix
I=eye(3); % Diagonal matrix
x0=[0 0 0 0 0 0]'; % Initial conditions
[t,x]=ode45('Fun1',[t0 t1],x0);
dx=[t,x]

plot(t,x(:,1),t,x(:,2),t,x(:,3));

Function 1 file:

function dx=Fun1(t,x)
global A B F Z I wdr
dx=zeros(6,1);

dx=[Z I ; -A -B] *x+[[0 0 0]' ; F]*sin(wdr*t);

end

please help me solve the problem =(