2: Viscosity

Example number 2.1, Page number 11

In [5]:
#importing modules
import math
from __future__ import division

#Variable declaration
eta=8.9*10**-4;    #coefficient of viscosity of water(Ns/m**2)
a=0.054*10**-2;    #radius of capillary tube(m)
l=56*10**-2;   #length of capillary tube(m)
h=34*10**-4;   #height of pressure head(m)
t=5*60;    #time of flow(s)
g=9.8;
rho=10**3;   #density of water(kg/m**3)

#Calculation
V=math.pi*h*g*rho*(a**4)/(8*eta*l);    #volume of water in 1 sec(m**3)
V5=V*t;    #volme of water flowing in 5 minutes(m**3)
m=V5*rho;   #mass of water flowing in 5 minutes(kg)

#Result
print "mass of water flowing in 5 minutes is",round(m*10**3,4),"g"

mass of water flowing in 5 minutes is 0.6697 g

Example number 2.2, Page number 12

In [7]:
#importing modules
import math
from __future__ import division

#Variable declaration
t1=6;   #time taken by water(s)
t2=3.6;   #time taken by alcohol(s)
rho1=10**3;  #density of water(kg/m**3)
rho2=800;    #density of alcohol(kg/m**3)
eta1=8.9*10**-4;   #viscosity of water(Ns/m**2)

#Calculation
eta2=t2*rho2*eta1/(t1*rho1);   #viscosity of alcohol(Ns/m**2)

#Result
print "viscosity of alcohol is",eta2*10**4,"*10**-4 Ns/m**2"

viscosity of alcohol is 4.272 *10**-4 Ns/m**2

Example number 2.3, Page number 12

In [12]:
#importing modules
import math
from __future__ import division

#Variable declaration
sigma=1.26*10**-3;   #density of medium(kg/m**3)
eta=2*10**-5;   #viscosity of medium(Ns/m**2)
r=0.2*10**-2;   #radius of body(m)
rho=8*10**-3;   #density of body(kg/m**3)
g=9.8;

#Calculation
v=2*(r**2)*(rho-sigma)*g/(9*eta);    #terminal velocity(m/s)

#Result
print "terminal velocity is",round(v*10**3,4),"*10**-3 m/s"

terminal velocity is 2.9356 *10**-3 m/s