Chapter 1 : Introduction

Example 1.1 Page No : 20

In [1]:
# Variables
d_r = 13640.; 			# Density of mercury in kg/m3
g = 9.79; 			    # Acceleration due to gravity in m/s2
z = 562e-03; 			# Difference in height in m
z0 = 761e-03; 			# Reading of barometer in m

# Calculation
P = (d_r*g*(z+z0))*(0.987/1e05); 			# Gas Pressure in bar

# Results
print "Gas Pressure is %.3f bar"%P

Gas Pressure is 1.744 bar

Example 1.2 Page No : 21

In [6]:
# Variables
d_r = 13.6e03; 			# Density of mercury in kg/m3
g = 9.81; 			# Acceleration due to gravity in m/s2
z = 710e-03; 			# Stean flow pressure in m
z0 = 772e-03; 			# Reading of barometer in m
P = 1.4e06; 			# Gauge pressure of applied steam in Pa

# Calculation
P0 = d_r*g*z0; 			# Atmospheric pressure in Pa
Pi = P+P0 ; 			# Inlet steam pressure in Pa
Pc = d_r*g*(z0-z); 			# Condenser pressure in Pa

# Results
print "Inlet steam pressure is %.3e Pa"%Pi
print "Condenser pressure is %.2e Pa"%Pc

Inlet steam pressure is 1.503e+06 Pa
Condenser pressure is 8.27e+03 Pa

Example 1.3 Page No : 21

In [3]:
# Variables
z = 0.760; 			# Barometer reading in m
# Part (a)
h1 = 40e-02; 			# Mercury height in vaccume in m
d_r = 13.6e03; 			# Density of mercury in kg/m3
g = 9.80; 			# Acceleration due to gravity in m/s2

# Calculation and Results
Patm = z*d_r*g; 			# Atmospheric pressure in Pas
Pv = h1*d_r*g; 			# Pressue in vaccume in Pa
Pabst = Patm-Pv; 			# Absolute pressure in Pa
Pabs = 101.325 - Pv/1000

print "Pvaccum = %.2f kPa"%(Pv/1000)
print "Pabsolute = %.f"%(Pabst/1000),"kPa"
print "40 cmHg vacuum : %.3f kPa"%Pabs

# Part (b)
h2 = 90e-02; 			# Mercury height in gauge in m
Pg = h2*d_r*g; 			# Gauge Pressure in Pa
Pabs1 = Patm + Pg ; 			# Absolute pressure in Pa

print "\nPgauge = %.f kPa"%(Pg/1000)
print "90cmHg gauge is %.3f"%(Pabs1/1000),"kPa"

# Part(c)
d_w = 1e03 ; 			# Density of water in kg/m3
h3 = 1.2 ; 			# Gauge Pressure water height in m
Pga = d_w*h3*g; 			# Gauge Pressure in Pa
Pabs3 = Patm + Pga ; 			# Absolute pressure in Pa
print "\n1.2 m H2O gauge is %.3f"%(Pabs3/1000),"kPa"

# rounding off error

Pvaccum = 53.31 kPa
Pabsolute = 48 kPa
40 cmHg vacuum : 48.013 kPa

Pgauge = 120 kPa
90cmHg gauge is 221.245 kPa

1.2 m H2O gauge is 113.053 kPa

Example 1.4 Page No : 22

In [23]:
from scipy.integrate import quad

# Variables
Pr = 1.033e05; 			# Required Pressure in bar

# Calculation
def pressure(p):
    return p**(-0.714);
g = 9.81; 			# Acceleration due to gravity in m/s2
H = ((2.5e05**0.714)/g)* quad(pressure,0,Pr)[0]; 			# Depth of atmosphere required in m

# Results
print "The depth of atmosphere required is %.3f Km"%(H/1000)
  
# note : there will be rounding off error because of quad function

The depth of atmosphere required is 69.203 Km

Example 1.5 Page No : 22

In [6]:
# Variables
m = 68. ; 			# Astronaut mass in Kg
g = 9.806; 			# Acceleration due to gravity in m/s2

# Calculation
a = 10*g ; 			# Lift off acceleration in m/s2
F = m*a; 			# Net vertical force in N

# Results
print "Net vertical force experienced by astronaut is %.0f N"%F

Net vertical force experienced by astronaut is 6668 N