import math
def meteor(n):
r = .09
m=7 
b=1.5e-3 
x = 200.*1000. 
v = -20.*1000. 
H = 7.6*1000. 
g = 9.8 # m/s2
t_max = -x/v*10. 
dt = t_max/n 
for i in range(n):
dx = v*dt
x = x+dx 
if x<0.:
return v 
F = b*v**2*math.exp(-x/H)-m*g
a = F/m
dv = a*dt
v = v+dv
return -999