Matlab code for modelling displacement over time as a plot

For part (a) of this question ive got this code but its not complete and im not sure if im on the right track. Please clarify what changes ive got left to make to answer this question and get the plot showing on my command window. Thank you!

My code:

function dydt = springdamper_threeblocks(t,y)

%Parameters for the system
m_susbar = 7;
m_wheel = 25;
ksus1 = 5000;
ksus2 = 12000;
ktire = 20000;

bsus1 = 500;
bsus2 = 400;

L = 0.4;

   xroad = 0.05*sin(8*(2*pi)*t);

   %Split up state vector y
   xwheel = y(1);
   xdotwheel = y(2);
   theta = y(3);
   thetadot = y(4);

   dydt_xwheel = xdotwheel;
   dydt_xwheeldotdot = (ksys2*(2*L/3)*thetadot + ksus2*(2*L/3)*theta-ktire*(xwheel-xroad))/m_wheel;

   dydt_theta = thetadot;
   dydt_thetadotdot = ((ksus1+4*ksus2)*theta)/m_susbar+((bsus1+4*bsus2)*thetadot)/m_susbar;

   dydt = [dydt_xwheel; dydt_xwheeldotdot; dydt_thetadotdot];

   %Timespan for simulation
   t_initial = 0;
   t_final = 5;
   t_span = [t_initial,t_final];

   y0 = [0;0;0];
   [t,y] = ode45('springdamper_threeblocks',tspan,y0);

   figure
   plot(t,y(:,1));
   hold on

   title('Block Displacements')
   xlabel('time(sec)');
   ylabel('Position(m)');
   legend('block1','block2');
   grid on;

   figure
   plot(t,y(:,3));
   hold on,

title('Angular displacement');
xlabel('time(sec)');
ylabel('Angular displacement(rad)');
legend('block1','block2');
grid on;

end