1 3 Flow over bicycle

% calculation of drag force on a bicycle

clear all
close all
clc

% Inputs
Cd = 0.8; % Drag coefficient
A = 0.1; % Surface Area (m^2)
rho = 1.2; % Density (kg/m^3)
v = [0:50]; % velocity (m/s)
l = 1; % unit length

drag_force = rho*A*v.^2*Cd*0.5;

plot(v,drag_force)
xlabel(\'velocity (m/s)\')
ylabel(\'drag force (N)\')
grid on

drag_square = rho*1*1*v.^2*Cd/2;
drag_triangle = rho*1^2*v.^2*Cd/4;
drag_circle = rho*3.14159*1^2*v.^2*Cd/16;

figure;
plot([Cd,drag_square],[Cd,drag_triangle],[Cd,drag_circle])
xlabel(\'drag coefficient\')
ylabel(\'drag force (N)\')
axis([0 1 0 1])
grid on

% please let me know why all curves are not displaying