dinamic-force.py

import numpy as np
import matplotlib.pyplot as plt 
from matplotlib import animation


fig, ax = plt.subplots(figsize=(8,8))


# Adjust axes limits according to your problem

ax.set(xlim=(-2,2), ylim=(0,600), xlabel='Position, meters', ylabel='Height, meters', title='Apple falling from tower')


# Params of the problem
T = 10. #s
m = 0.3 #kg
g = 9.8 #m/s^2
v0x = -0.1 #m/s
H = 553. #m


# setting a timestep to be 50 ms
dt = 0.05 #s
N = int(T / dt)

# Allocating arrays for 2D problem
v = np.zeros((N+1,2))
r = np.zeros((N+1,2))
f = np.zeros((N+1,2))

# Initial conditions:
r[0] = np.array([0., H])
v[0] = np.array([-v0x,0.])

# The only force is gravity
f[:] = np.array([0., -m * g])


## Run dinamics 
for n in range(N):
    v[n+1] = v[n] + f[n]/m * dt
    r[n+1] = r[n] + v[n+1] * dt
    
# Drawing the first data point
scat = ax.scatter(r[0,0], r[0,1], marker='o', c='g', s=200)


# animating
def animate(i):
    scat.set_offsets(r[i])
    
ani = animation.FuncAnimation(fig, func=animate, frames=N)
## this function will create a lot of *.png files in a folder 'CNtower_frames'
## and create an HTML page with a simulation
ani.save('CNtower.html', writer=animation.HTMLWriter(fps=1//dt))
plt.close()
#ani.save('CNtower.mp4', fps= 1//dt)