import matplotlib.pyplot as plt
import numpy as np

##########################
# free fall

plt.clf()

n = 100
dt = 0.1
x0=0
y0=1.
vx=1.
vy=0.

x=[]
y=[]

x.append(x0)
y.append(y0)

for i in range(1,n):
   x.append(x[i-1] + vx*dt)
   y.append(y[i-1] + vy*dt)
   vy = vy - 10*dt

plt.plot(x, y)

plt.show()