#!/home/misha/venv/bin/python
import numpy as np
import matplotlib.pyplot as plt
import scipy.integrate as ode
import matplotlib.animation as animation

g_rask=9.814
r_keha=1.8
s_keha=np.pi*r_keha**2
c_keha=0.47
v_keha=4.*np.pi*r_keha**3/3
m_keha=15.
ro_keha=m_keha/v_keha

p_ohu=100000.
t_ohu=293.
mu_ohu=29.
r_gaas=8314.

ro_ohu_0=p_ohu*mu_ohu/(r_gaas*t_ohu)
p1=g_rask*mu_ohu/(r_gaas*t_ohu)
p2=0.5*c_keha*s_keha/m_keha

def func(y,t):
   yp=np.zeros_like(y)
   yp[0]=y[1]
   ro=ro_ohu_0*np.exp(-p1*y[0])
   v=np.abs(y[1])
   yp[1]=g_rask*(ro/ro_keha-1.)-p2*ro*v*y[1]
   return yp

y0=[0.,0.]
time=np.linspace(0,5000,num=10000)
res=ode.odeint(func,y0,time)

fig,[p1,p2]=plt.subplots(1,2)
p1.plot(time,res[:,1])
p2.plot(time,res[:,0])
p1.grid()
p2.grid()
plt.show()