Chapter 2 - Fundamental Concepts

Example 1 - Pg 18

In [1]:
#calculate the potential energy
#Initialization of variables
z=100 #ft
m=32.1739 #lbm
#calculations
PE=m*z
#results
print '%s %.2f %s' %("Potential energy =",PE,"ft-lbm")

Potential energy = 3217.39 ft-lbm

Example 2 - Pg 21

In [2]:
#calculate the absolute energy of this mixture and the change in mass
#Initialization of variables
m0=18.016 #lbm
gc=32.1739 #lbm ft/lbf sec^2
c=186000*5280
dU=94.4*10**6 #ft-lbf
#calculations
U=m0/gc *c**2
dm= -dU*gc/c**2
#results
print '%s %.2e %s' %("Absolute energy of this mixture =",U," ft-lbf")
print '%s' %("\n In case b, there is no change in mass")
print '%s %.2e %s' %("\n Change in mass =",dm," lbm")
print '%s' %("The answers are a bit different due to rounding off error in textbook.")

Absolute energy of this mixture = 5.40e+17  ft-lbf

 In case b, there is no change in mass

 Change in mass = -3.15e-09  lbm
The answers are a bit different due to rounding off error in textbook.