Chapter 2 Fundamental Concepts

Ex:2.1 Pg:34

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

Potential energy = 3217.39 ft-lbm

Ex:2.2 Pg:35

In [1]:
#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 "Absolute energy of this mixture = %.2e ft-lbf"%(U)
print "\n In case b, there is no change in mass"
print "\n Change in mass = %.2e lbm"%(dm)
print "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.