How do get a ball bounces off the wall?

How do get a ball bounces off the wall?

The ball has to bounce off the wall. Help me.

The code I made is as follows.

clc,clf,clear
v0=10;
t(1)=0;x=0;y=0;               
plot(x,y,'o','MarkerFaceColor','b','MarkerSize',8)
                                
axis([0 10 0 40])             
M(1)=getframe;
dt=1/32;
open(v);

    for i = 2:1000
      t(i)=t(i-1)+dt;
      x=t(i);
      y=v0*t(i);
      plot(x,y,'o','MarkerFaceColor','b','MarkerSize',8)
      axis([0 10 0 40])
     
      M(i)=getframe;
      writeVideo(v,M(i));
      if y>=40, break, end
    end

close(v);

Answer 1

[Image Analyst]

Basically, just reflect it

yMax = 40;
if y > yMax
    distanceBeyond = y - yMax;
    y = yMax - distanceBeyond;
end