Program to calculate drag forces experienced by a cyclist.

Program #1: Plot velocity v/s drag force for a cyclist

'''Program for calculating and plotting the drag force experienced by a cyclist when riding at different speeds.
Here, the Drag force is calculated as '0.5*density*frontal_area*velocity^2*drag_coefficient'
'''
import math # import required modules.
import matplotlib.pyplot as plt

#define variables.
c_d = 0.8 # drag coefficient
A = 0.1 # frontal area in m^2
rho = 1.2 # density of air in (kg/m^3)
v = [] # array of velocities in m/s.
#F_d = 0.5 * rho * A * (math.pow(v, 2)) * c_d # drag force in (kgm/s^2)
D = []
for velocity in range(0,100):
    v.append(velocity)

print(v)

for velocity in v:
    F_d = 0.5 * rho * A * (pow(velocity, 2)) * c_d
    D.append(F_d)

print(D)

plt.plot(v,D)
plt.xlabel('velocity(m/s)')
plt.ylabel('drag force(N)')
plt.savefig('velocity versus drag force')
plt.show()

Explanation:

Imported the necessary modules and defined the required variables

A for loop is used to create a velocity list, v[], with velocities ranging from 0 to 100 m/s.

Another for loop is used to calculate the drag force value corresponding to each of the velocities in v[].

A list of all the drag forces, D[], is created by using '.append()' inside the second for loop.

The list of velocities and the list of drag forces are used to plot the required velocity v/s drag force graph.

plt.plot(x,y) was used to plot the graph

plt.savefig() was used to save the plots as .png files.

Output:

The output shows the list of velocities, the list of drag forces and the velocity vs drag force plot.

Program #2: Plot drag coefficient vs drag force for a cyclist riding at a constant speed assuming the same frontal area at all instances.

'''Program for plotting a graph btwn drag coefficient and drag force for a cyclist riding at a constant speed (for a range of drag coefficients.)'''

import math
import matplotlib.pyplot as plt
import numpy as np

v = 10 # velocity in m/s
rho = 1.2 # density of air in (kg/ m^3)
A = 0.1 # frontal area in m^2
c_d = np.linspace(0, 1, 11) # array of drag coefficients
print(c_d)
#f_d = 0.5 * density * frontal area * velocity^2 * drag_coeff (drag_force in Newton)
D = [] # array of drag forces corresponding to different drag_coeff's
for drag_coeff in c_d:
    f_d = 0.5 * rho * A * (math.pow(v,2)) * drag_coeff
    D.append(f_d)

print(D)

plt.plot(c_d, D)
plt.xlabel('drag coefficient')
plt.ylabel('drag force(N)')
plt.savefig('drag_coefficient versus drag_force')
plt.show()

Explanation:

Imported the necessary modules.

Defined the required variables.

Created an array of drag coefficients using np.linspace()

Used a for loop to calculate the drag force value corresponding to each value of the drag coefficient.

Used a list, D[] to hold all the drag force values.

plt.plot(x,y) was used to plot the graph between the drag coefficient and drag force.

Used plt.savefig() to see the plots.

Output:

The output shows the drag coefficient values, corresponding drag force values and the plot between the two.