In [1]:

```
#Calculate the time taken by water in a long pipe to reach its steady state velocity
#let (new)*t/r0^2 be denoted by y
# variables
y=0.05 #dimentionless
r0=0.077 #m
mew=1 #Pa.s
rho=1000.0 #Kg/m^3
# calculations
new=mew/rho #m^2/s
t=y*r0**2/new #s
# results
print "the time taken by water in a long pipe to reach its steady state velocity is % f seconds"%t
```