Chapter 11 :Thermodynamics

Example 11.4 , Page no:63

In [1]:
import math
from __future__ import division
 
#initialisation of variables
lf=335; #heat of fusion in kJ/kg
g=9.8; #gravitational constant in m/sec square

#CALCULATIONS
h=lf/g; #height in km

#RESULTS
print"Height in km =",round(h,3);

Height in km = 34.184

Example 11.6 , Page no:64

In [2]:
import math
from __future__ import division
 
#initialisation of variables
hc=1.1*10**4; #heat of combustion of heat oil in kcal/kg
p=10**6; #Power in Watt
t=3600*24; #time in sec
e=0.4; #efficiency

#CALCULATIONS
w=p*t; #calculating power produced in a day in Joule
hi=w/e; #Heat input in Joule sice efficiency=output/input
hi=hi/(4.185*10**3); #for calculating heat input in kcal
m=hi/hc; #amount of fuel burnt each day in kg

#RESULTS
print"Amount of fuel burnt each day in kg =",round(m,3);

Amount of fuel burnt each day in kg = 4692.082

Example 11.7 , Page no:64

In [3]:
import math
from __future__ import division
 
#initialisation of variables
w=40000; #weight in lb
t=3600; #time in sec
g=32; #gravitational constant in ft/sec square
v1=2500; #initial velocity in m/sec
v2=400; #final velocity in m/sec

#CALCULATIONS
W=(w/(2*g))*((v1*v1)-(v2*v2)); #calculating Work done in ft.lb using work done=difference in Kinetic Energy
p=W/(t*550); #calculating Power using P=W/t since 1hp=550 ft.lb/sec;

#RESULTS
print"Power Ouput in hp =",round(p,3);

Power Ouput in hp = 1922.348

Example 11.8 , Page no:65

In [4]:
import math
from __future__ import division
 
#initialisation of variables
t1=327+273; #temp in Kelvin
t2=127+273; #temp in Kelvin
hi=4185; #1 kcal=4185 Joule

#CALCULATIONS
eff=1-(t2/t1); #calculating efficiency
W=eff*hi; #calculating Work in joule

#RESULTS
print"Work in Joule =",round(W);

Work in Joule = 1395.0

Example 11.9 , Page no:65

In [5]:
import math
from __future__ import division
 
#initialisation of variables
woa=3000; #work ouput of a in Joule
wob=2000; #work output of b in Joule
woc=1000; #work output of c in Joule
hi=4185; #1 kcal=4185 Joule
t1=500; #temp in Kelvin
t2=300; #temp in Kelvin

#CALCULATIONS
eff=1-(t2/t1); #efficiency
effa=woa/hi; #calculating efficiency of a
effb=wob/hi; #calculating efficiency of b
effc=woc/hi;#calculating efficiency of c
effa1=effa*100;
effb1=effb*100;
effc1=effc*100;

#RESULTS
print"Efficiency of A =",round(effa1,3);
print"Efficiency of B =",round(effb1,3);
print"Efficiency of C =",round(effc1,3);

Efficiency of A = 71.685
Efficiency of B = 47.79
Efficiency of C = 23.895

Example 11.10 , Page no:65

In [6]:
import math
from __future__ import division
 
#initialisation of variables
t1=267+273; #temp in Kelvin
eff=0.25; #efficiency

#CALCULATIONS
t2=t1*(1-eff); #calculating t2 using eff=1-(t2/t1)
t3=t2-273;

#RESULTS
print"Temperature in celcius =",round(t3,3);

Temperature in celcius = 132.0

Example 11.11 , Page no:65

In [7]:
import math
from __future__ import division
 
#initialisation of variables
t1=34+273; #temperature in Kelvin
t2=35+273; #temperature in Kelvin

#CALCULATIONS
r=((t2**4)-(t1**4))/(t1**4); #calculating percentage difference in radiation
r1=r*100;

#RESULTS
print"Percentage difference in radiation =",round(r1,3);

Percentage difference in radiation = 1.309